Vannin' Home
Posted By: 1983G20Van 1997 Chevy Express Cobra Conversion - May 27th 2021 5:49 am
Thought I would show my project van. Parents bought it in 98 with about 13,000 miles on it. I have had it since 2012 when my mom said get it out of my driveway. My dad had passed away in 2011 and it had been his daily driver. Had to make some wiring harness repairs and decided to just go ahead and yank the engine and clean the whole engine compartment. Gave me some much needed time to work on other parts of it. The van was a 1500 but has been converted to full 1 ton specs. Suspension, running gear, brakes and all are right out of a 2002 15 passenger church van.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 27th 2021 6:05 am
Current big project, remove everything from the firewall, clean and paint the front frame section, bedline both sides of the inner fenders and firewall that shows and repair the harness. Once that is done the 383 is getting dropped back into it. I had a a rear main seal leaking on the fresh 383 and with the front clip and headers off already doing the steering gearbox and harness it was only about an hour job to pull the engine again.

What the 383 sounds like with a Q-Jet on it and the open tri-ys off the Express van.

https://youtu.be/l7XDuEvqFR4

Currently adding flex fuel sensor and fuel pump hotwire wiring into the main harness as well as redoing my electric fan harness. Also adding an a/c pressure transducer. This 97 is running on a Blue/Green terminal 1 meg 2005 DBC 6.0L Express PCM with a 2005 Mexican GMT800 L31 5.7L vortec based engine calibration. The Racetronix hotwire kit was an old modification that feeds the fuel pump directly from the output stud of the alternator through 10 gauge wiring and a 30 amp relay as well as geounds the pump through a 10 gauge ground wire. Was necessary for the 340 LPH fuel pump upgrade to support my ~500 hp 383 on E85. Those 6.2L Raptor injectors on the marine intake get thirsty on E85 around 5,000-6,000 rpm.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 27th 2021 6:19 am
Just made an entire post in the GM how to on this. Updating the mirrors to the dual glass mirrors found on a 2012 Express while retaining the power and heater functions. Repinned the mirror harness to match the 97 and they work perfectly. Also still have to wire it in but had a 10 year old Gentec Auto dimming homelink rearview mirror that was brand new in the box that I just installed on the windshield.

https://www.vanning.com/threads/ubb...o-2012-dual-split-mirror.html#Post776779

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Posted By: NateB Re: 1997 Chevy Express Cobra Conversion - May 27th 2021 9:31 am
Nice work!!
Posted By: newkirkinc1 Re: 1997 Chevy Express Cobra Conversion - May 27th 2021 12:29 pm
Yes iy is . sweet!
Posted By: lukester Re: 1997 Chevy Express Cobra Conversion - May 28th 2021 2:53 am
Nice looking van you got there.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 28th 2021 3:53 am
Thank you for the complements guys!

Some of the engine build for those of us that like a hotrod of a van. At 11:1 with 210cc heads it is not messing around for power. 218/228 @ 0.050 roller cam on a 108 LSA and 104 ICL with 0.578 lift with the 1.7 full roller rockers. Effortlessly spins 6,500 with the balanced rotating assembly, 6" H-beam rods and forged Weisco slugs. Pump premium or E85 only for it. Heads were ported by Lloyd Elliot and flow very close to 300 cfm on the intake and 200 cfm on the exhaust through a 2.02/1.60 valve.

I had the marine intake, 300 hp marine cam, 1.7 rockers and the headers on the old 350. How it ran with the old 350 Vortec and the 300 hp GM 395' marine cam that only made power to 5,100 rpm. The hotter 357 hp SPO cam made power to 6,000.

https://youtu.be/Sc-DZDdjc7o

I later put a bigger 357 hp SPO 350 cam in the 350 (a little smaller than the 383s cam) and 3" electric cutouts before the muffler. This is what the bigger cammed 350 sounded like. Apparantly never made a WOT video of it though with that cam.

https://youtu.be/4GLiLvlr2MM

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 28th 2021 4:20 am
I had a custom converter built by Performance Torque Converters of North Texas out of Kennedale, TX that has a billet front cover, bigger lockup clutch, fully brazed fins and is restalled for the 383. The old 350 was pushing through the Pheonix out of Weatherford, TX built converter. The Pheonix built one is the smaller diameter FWD V6 based body. These were both built to stall roughly 2,600 rpm yet the old 350 was stalling the smaller one 2,800+, you can hear how loose it was in the WOT acceleration video. Given that I tow a 6,000 lbs travel trailer with the van the smaller converter was not going to cut it behind the 383. 383 would have likely stalled it higher than 3,000 rpm and built a massive amount of heat trying to get nearly 13,000 lbs rolling from a stop.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 28th 2021 4:35 am
The towed rig is a 2015 Jayco 23RLSW. Great for a bachelor or a couple for longer term or for a shorter trip with a kid or two or perhaps even the parents or in-laws for a weekend. With a bedroom in the nose and the rest of the sleeping space in the rear it is pretty nice to get away in. It sleeps 6 comfortably and I have actually had 7 in it on one trip. Inflatable air bed fits perfectly in the floor with the slide out. 7 happens to be what the van carries as well. It was after that 500 mile trip the van became 1-ton equipped. It has Helwig front and rear sway bars under it. 1-1/2" front and 1-3/8" rear and the trailer is setup on a good weight distributing hitch (spring bar type, no chains) with built-in antisway.

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Posted By: pontiac59 Re: 1997 Chevy Express Cobra Conversion - May 28th 2021 5:54 am
These are nice vans if you like working on them. If you have to get into a door for anything, consider changing the handles, they get brittle with age and can break.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 30th 2021 12:39 am
Received the $20 AEM GM EV6 injector harness today and fit it to the fuel rails on the marine intake. I picked up an assortment of the Deuschworks connectors on Amazon to build a matching end for the engine harness. Plan to install the leftover connector on the OEM spider connector just in case I ever need to quickly swap back to the stock intake in the future for emissions reasons. Nice to have near plug and play options should the need ever arise.

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Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - May 30th 2021 4:41 am
Nice job and it sounds great. chevy
Posted By: newkirkinc1 Re: 1997 Chevy Express Cobra Conversion - May 30th 2021 1:43 pm
Awesome!
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 30th 2021 1:43 pm
Originally Posted by pontiac59
These are nice vans if you like working on them. If you have to get into a door for anything, consider changing the handles, they get brittle with age and can break.

Changing the speakers, tweeters, exterior handles, power window and lock switches, lock actuators and the window motors while I am in there in addition to greasing the power window regulators with the correct grease. Also need to lube the window runs while I have it apart as well. Windows have been slow for years and the lock actuators weak. Driver outer handle has function but it has been loose for a couple of years.

I prefer the 96-02 vans to the 03+. Not a fan of the $$$ failure prone sealed hub bearing assemblies up front as well as the BCM and all the added wiring GM added somewhere in the 03+.Finally not a fan of the sluggish low-end torque of the LS that makes them downshift on even slight grades. The old 5.7L had lots of low-speed torque. Even rolling on 31.5" tall 20s with a 3.73 gear the old 350 would pull the Express up a 6% grade in overdrive at highway speeds without unlocking the converter. Several years ago going through Kentucky I took advantage of the sustained heavy loading of the uphill climbs and dialed in the spark timing map going down the road while my little brother was driving. I had realtime tuning on the 0411 and was able to make changes with the engine running. Old 350 with the GM 395' 300 HP 350 Marine/Ramjet/HT383 cam in it felt like an electric motor pulling that van as the throttle increased. Even down at 2,000 rpm budge the loud pedal and it would respond with more power.

https://youtu.be/UgwvwHzk74c
Posted By: Wedgy Re: 1997 Chevy Express Cobra Conversion - May 30th 2021 6:51 pm
Welcome to the Site Sir with that well wrenched on Rig. That's alot of well done work. Nicely done! Quite sure Pops is proud.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 31st 2021 3:25 am
Originally Posted by Wedgy
Welcome to the Site Sir with that well wrenched on Rig. That's alot of well done work. Nicely done! Quite sure Pops is proud.

I am sure pops would be. Although when I put the first replacement Vortec 350 in this van back in 2005ish he was pretty mad at me. The old 350 had self destructed on startup on him by hydro locking on coolant from a leaking intake gasket. Broke the #2 connecting rod which then munched the cam and block. When I put the new crate engine in, I replaced the spider and removed that stupid EGR diffuser plate on the vortec throttle plate. The torque converter had also been slipping so I put a reman for a 4.3 S10 into it. Behind the L31 it stalled 2,500 rpm. Then I had a friend that had TunerCatsOBD2. We put a bit of a power tune in the PCM. The tuning included a massive timing table change. Not having much to go off of since neither of us had worked much on the 5.7L Vortec, my friend had a Ramjet 350 timing table. We put the Ramjet 350 timing map into the Vortec PCM and pulled a couple of degrees of timing out of the whole map for the weight of the van and the fact dad always ran 87. Dad got it back after I had broken in the engine. He bitched at me for a couple of weeks because he could not accelerate from a stop without burning the tires which I found odd because his other vehicle was a 1994 Ram 2500 regular cab long bed 2wd with the V10 Magnum which was the lightest truck you could get that engine in. The factory PCM had died in that truck and I had replaced it with a mopar performance unit calibrated for a colder thermostat and a low restriction exhaust and air cleaner. Cats had failed so we did what everyone else had done and gutted them. That truck was way touchier than the van on the get up and go pedal. My brother who was still at home and rode to school with my dad said my dad would burn the tires out of every stop and not intentionally. Eventually he relearned the go pedal and enjoyed having the extra get up and go when needed. He upped it to P295/50R15s from P235/75R15s when it needed tires and it was much easier to get off a stop without smoking the tires. My dad was mostly a putt around kind of guy but he would occasionally break his foot off in the go pedal. I remember one time he had the Q-Jet on the old 83 G20 305 singing for several miles with the needle on the 85 mph speedo wrapped around and pegged on the back of the 0 mph stop. First time I had ever been that fast in a vehicle. He had a guy in about a 95 Chevy truck that kept trying to cut him off so he just flat footed the carb 305 that was not governed like the TBI was and made him vanish in the rearview mirror. The 83 had eaten a cam and lifter somewhere around 120K miles when I was about 10 in 1995. Dad was a coach amd a teacher on a limited budget and had some mechanical experience and I helped him over the course of a week of summer nights pull the heads, take them to the machine shop and replace the cam and upper end gaskets. He had bought a couple of small block chevy books at the local bookstore and we would read up during the heat of the day and work at night and sleep in the next morning. For a 305 it ran really well. Machine shop gave him some kind of .454 lift cam that he said would make it pull dads trailer better. Years later I think I know what cam went into it but it was a huge kick in the pants over the tiny factory cam and it had a little lope to it. After we got the cam broken in we had driven the van around with the dog house off and played around with the distributor to get the timing set by ear. Q-Jet had an awesome sound opening up with the doghouse cover off. This kickstarted my interest in cars and engines.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - May 31st 2021 8:07 pm
Started my day off this morning by deleting the EGR wiring. The pink switched power wire is going to get extended to control the switched power side of my fan relays. Then moved on to cleaning the passenger inner fender and truck bed coating it. Next step is to remove the a/c box off the firewall. Was waiting on some penetrating oil to help release the a/c fitting for the rear a/c liquid line or I would have it off already. I was able to get the fitting to release but now waiting on the truck bed liner I already sprayed to dry. OEM power antenna is getting removed for a fixed FM/CB antenna. Van is getting a small Uniden CB radio installed in the dash where the factory CD player once resided.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - June 03rd 2021 1:13 am
So my OEM airbox had basically fallen apart on this 97. I looked on GM Parts and its discontinued. Tried the local treasure yard and found several in the same shape or worse than mine. Looked at an 01+ and picked one up. Would not clear the fan shroud. Tried to find an aftermarket CAI kit. NONE on the market. Then discovered K&N makes a kit for a Kodiak with the 6.6 diesel that shares the same firewall as the van. Called K&N to try to buy just the heatshield and the filter from them. The woman on the phone was absolutely not helpful at all. Seems the only way you could get the part even if you already had the kit and needed a replacement part would be to buy the whole kit again. She suggested I look at Spectre for something "universal" despite making the product I need and wanted to buy with debit card in hand. Never will buy or suggest K&N or Spectre parts again after having run their filters in all my vehicles over the past 18 years and suggesting and selling hundreds of K&N and Spectre products to customers. Their customer service was that bad. Its ashame because they already make the perfect shaped heatshield and perfect sized filters for the 96+ Express vans. The filter is even a 3.5" like our OEM MAF. Could literally fabricate some mounts in about 30 minutes and bolt it in. Still scratching my head as to why one of the most common vans ever built does not have a CAI kit made for it yet they build one for an oddball one or two year run of a very limited production Kodiak truck. K&N also got a nice 1 star review left on their google reviews. Absolutely zero chance of me paying $350 for a stamped metal heatshield, a few bolts and nuts and a cone filter even though it would fit and look great. Even more puzzling is that K&N builds an intake kit for an Econoline van with the modular V8s. I see 3-4 Express/Savanna vans for every Econoline on the road and GM has had a much longer run than Ford.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - June 20th 2021 9:14 pm
Have not been able to get too much done lately working 6 day work weeks. However I did get the rear-view mirror wired and the harness reloomed. Front end is back together and I am about to have it on all 4 wheels again. I decided to do an exterior LED conversion and update the look of the rear with some aftermarket tailights. Will update once I get them installed and the LEDs and LED electronic flasher installed.

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Posted By: newkirkinc1 Re: 1997 Chevy Express Cobra Conversion - June 20th 2021 9:17 pm
Those are nice!
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - June 21st 2021 8:49 pm
LEDs arrived yesterday afternoon. Tailights shipped today, should have them in my hands on the 24th. Spending some time at my shop today on my only day off this week. Took apart all the trim to get access to the tailight mounting points and swapped over the LEDs. Took a couple of pictures after swapping the high mounts and the RH side bulbs to LEDs. I forgot that the reverse lights are 1156s and ordered 1157s. Ordered a pair of 1156s and going to keep the extra pair of 1157s for spares. These stock flasher seems to flash these LEDs just fine with only the rear turn signals in place. Guess that makes sense because I have towed all kinds of trailers without the flashing speed changing. I also forgot that I had put Silverstar bulbs in the back about 8 years ago. The hazy blue coating the apply had peeled off the RH side bulbs. The Silverstars are already brighter than normal 1157s. Even still the LEDs are much brighter than the Silverstars.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - June 22nd 2021 5:49 am
Played around with the lights some more this evening. Updating every exterior bulb on the 97 Chevy to LED. Also going with the 4 HI mod that keeps the low beam headlights on with the high beams. With around 30,000 lumens of 6,000k light per side (more when I install driving lights in the factory holes in the valance) I will not be the one to play lets leave our brights on coming at me on a two lane road with. Also will not be the one you want to tailgate. The brake lights and turn signals are much brighter than the running lights. The replacement projector style tailights should make them even brighter. I also forgot the front turn signal and running lights required two pairs of 1157 amber bulbs. Ordered another pair of them to go along with the 1156s. Also ordered a LED bulb to replace the burned out factory underhood trouble light bulb. It has cost me a little under $200 to swap out every single exterior bulb to LED including the headlights and IMO well worth it. Those extra long ones with the heatsink or fan will not fit.

As you can see in the headlight picture, huge difference between Silverstar headlight bulbs and a decent LED headlight bulb. The composite headlight Express vans use 9005 and 9006 headlight bulbs. I found some that fit within the dimensions of a stock bulb externally.

I also spoke too soon on the flasher. When I put the front bulbs in place the stock unit hyperflashed. Took about 5 minutes to change to the $17 LED flasher. Its located under the column and you can reach it and remove it without taking anything apart. New LED style replacement has it working properly again. One flasher runs the turn signals and the hazards on the 96+ Express.

Would have gotten more done but a couple of buddies of mine were working at their shop across the street. Helped them troubleshoot a no start on a LY6 6.0L swap into a 90 R30 crew cab. Ended up being a cam sensor connector with the signal and 12 volt source wire swapped and the fuel lines swapped between the sending unit and the fuel filter on the Vette fuel filter. Vette fuel filter will not flow fuel through it if you try to push fuel into the internal regulator return port. You also do not get fuel or spark without a cam signal on the newer gen 4 58x engines.

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Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - June 23rd 2021 4:56 am
Nice upgrade. ( wish I had some buddies that had a shop across the street ) chevy
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - June 24th 2021 3:40 am
Originally Posted by SDMickey
Nice upgrade. ( wish I had some buddied that had a shop across the street ) chevy

Buddies having a shop across the street is cool but I am extremely fortunate to be able to lease a place of my own.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - June 25th 2021 1:12 am
With parts becoming hard to find I went after alot of what I needed to finish the van. I now have probably close to a full months worth of shop time to work on the van parts wise. Ordered an android head unit with a 10.1" screen, rockford fostgate front speakers (rears to come soon), all the AN lines and fittings to do the trans and power steering as well as a Derale 24" frame mount oil cooler for a power steering cooler that is going under the radiator core support in the stock location of the vans that had the factory tube and fin p/s cooler. Still have to button the 383 back up with a new crank seal and install it. Still have some pressure washing to do in the engine compartment. Also have to finish putting the LH front suspension and brake system back together. Finally have a broken shift cable to change. Working 60+ a week I have so much to do and so little time to do it in. I also found the connector that matches my Bosch Marine T-Map sensor so that I do not have to adapt the van map sensor as well as a connector kit that has the matching connector to the $20 AEM EV6 fuel injector harness I picked up. I got a whole mess of additional weather proof connectors to build whatever quick disconnect I want for the cost of a single pigtail. I have a radiator and e-fans to mount along with the fan harness and the a/c pressure sensor harness update. Have to crimp the ac pressure sensor connector fitting into the discharge side of the a/c manifold hose. I have HPS red silicone hoses to change out all the heater hoses and the matching stainless silicone hose clamps. I have both the front and rear plastic heater control valves to change. Have a rear expansion valve and front orifice tube to change as well as flush the a/c system. I have one of the new wafer thin style CSF parallel flow condensers and a new UAC Sanden SD7H15 compressors. I have all the GM seals to reseal the heater and evaporator case as well as a new OEM heater core. Also have a hydroboost and Redhead steering gearbox to install. I have exterior door handles and all the power window and power lock switches to change. Might do the window motors while I am at it. I also have a +3qt aluminum trans pan and a HD2 shift kit for the 4L85E. I have an Trutrac and 4.56 gears for the 10.5" along with the install kit. I am looking at a license plat bracket, rear door handle with the built-in backup camera they make. Tired already just from thinking about it all. I have been gathering parts for this build for 6+ years.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - June 29th 2021 3:26 am
Managed to get some more work done today. Couple of before and afters. Tailights are installed. Also installed my Rockford Fostgate front speakers and tweeters. The main speakers installed right into the OEM brackets but I still have to mount the tweeters. I measured the rear overhead speakers and they are 5x7s. Then I discovered working on the tailights with the music playing that the rear doors have a 2nd pair of rear speakers down low on them behind a fabric covering on the door panels that I never realized were there. Guess I get to order 2 more pairs of Rockford Fostgates for the rear. I know the name is twisted but with the OEM door panel and factory speaker grille over it, nobody will see it. I also mounted the Derale 13224 under the metal support that holds the radiator core support and started plumbing the cooler and the AN lines for the trans and power steering. Forgot to take pictures of that progress.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 03rd 2021 12:24 am
So I just started the next project on the van and it is quite an undertaking. First I removed the OEM radio and cd player. Fitted a 10.1" touch screen Android head unit. I still have to route and mount the backup camera, GPS antenna and the bluetooth hands free microphone. I hooked the GPs and Microphone up and they work very well. The GPs antenna grabbed 5 satellites laying on the dash inside my shop. I connected the radio to the hot spot on my phone and downloaded the Texas map and then downloaded OBDLink that ties to the OBD2 Elm327 device I have. I have swapped out the front speakers and the tweeters. I have the rear 5x7 and 6x9 speakers on order. Rockford Fostgate Punch line all the way around. The 5x7s are 3 way and the 6x9s 4 way. The internet based apps play very clearly off my hotspot. I will need to cut the radio craddle, reinforce it and find a way to mount the ac controller in the former CD player opening. The electrical connections and vacuum hoses need to be relocated to the lower opening in the dash behind the craddle but they are plenty long to reach. I will seal the upper opening off with a piece of textures ABS plastic cut to fit the opening. I used a Metra harness and the radio harness and spliced then together with solder and heat shrink before wrapping the wires with 3M harness looming tape to make a plug and play conversion harness. Still have to route a wire to the parking brake switch and the reverse input to the cluster. Finally have a dead Clifford alarm to remove out from under the dash and a new Metra power antenna to install to replace the failed OEM power antenna. I also installed the relay setup to give me 4 HI on the headlights in that the low beams turn back on with the high beams. With 6,000K LEDs the sucker is bright. Finally I ordered a flush mount dual USB connector to keep from having random USB cables hanging out from under the dash. You may notice I have yet to drop the 383 back in. That install is coming soon. Still have a few minor things to do and it is much easier to access the wiring and under dash without the engine in the way.

Head unit installed in the dash using a Metra adapter.

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A/C controls now hidden behind the unit

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Opening where the factory CD player resided and the a/c controls will be located.

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Unit powered up and a Bowtie boot screen

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Just some random playing around. It is capable of running apps in a split screen.

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USB connector that I am moubting in the glovebox section that bolts on behind the engine dog house. Will install it next to my wideband afr gauge and my exhaust cutout switch.

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Finally 4 HI on the headlights after the relay mod.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 03rd 2021 12:54 am
I have found a couple of C4500 Kodiak/Topkick dashes and really fighting the urge to swap the whole dash. Honestly looking at the structure that mounts to the firewall I am reasonaly certain it is not even the whole dash that has to be swapped. Rather just some of the pieces that bolt to the structure. The dash pad, lower trims, and the cluster bezel along with a coupe of air ducts and the radio craddle. There isna company that makes a really nice wood dash kit almost matches the wood in the van as well.

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Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - July 03rd 2021 6:30 pm
Wow; pretty cool head unit.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 05th 2021 4:54 pm
Switched gears this morning because I got tired of working under and in the dash. Installed my power steering cooler and plumbed the power steering/hydroboost system. Was also given a 31 case size marine optima combination deep cycle starting battery that was supposed to be bad. It charged right up on my computerized charger and fit in the vans stock tray although I need to figure out a hold down.

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Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - July 06th 2021 1:24 pm
Nice score; especially on the OPTIMA battery. Good product.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 09th 2021 1:08 am
Originally Posted by SDMickey
Nice score; especially on the OPTIMA battery. Good product.
Thanks!

I spent some more time over at the shop last night. Working on building trans cooler lines.

The Trucool D7B I have been running compared to the factory cooler still laying around the shop. DB7 is roughly 50% larger(wider and taller) and roughly twice as thick. It probably has 3 times the cooler fin surface area the stock one does. Replacing the leaking factory lines and quick connects with AN on it too. My previous converter was a 10" job that stalled 2,700 rpm and the D7B plumbed in after the radiator cooler kept the trans around 160°F max even towing my travel trailer. The condensor has a nice trans fluid stain on it that is filled with dirt and it is absolutely full of small rocks and debris. Good thing it is getting replaced with a new parallel flow.

[Linked Image][Linked Image]

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Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - July 09th 2021 5:26 am
Nice work my friend. You are so lucky to have a shop across the street,
Posted By: shaggy Re: 1997 Chevy Express Cobra Conversion - July 09th 2021 1:17 pm
Nice work, Do you know much history on the Cobra company?
My van is a cobra too but from '79.

https://www.vanning.com/threads/ubb...e-ultimate-custom-camper.html#Post403571

I wonder is it the same people or did the name just get sold on.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 09th 2021 3:15 pm
Originally Posted by shaggy
Nice work, Do you know much history on the Cobra company?
My van is a cobra too but from '79.

https://www.vanning.com/threads/ubb...e-ultimate-custom-camper.html#Post403571

I wonder is it the same people or did the name just get sold on.

Fairly certain it was a different group. My Cobra was made in Elkhart, Indiana by Advantage Enterprises. Advantage Enterprises built Advantage, Cobra and Rockwood conversion vans. I know Cobra was around until atleast 2005 as I have seen a 2005 Express with the Cobra conversion. I have also seen a mid 90s G-van that was a Cobra as well.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 10th 2021 5:04 am
Routed the BP engineering GMT800 fan harness and fitted the radiator today. Tested the fan harness and it works the way it was intended. The harness uses ground triggered relays that will be controlled by the PCM. On low speed with the motors in series for 6 volts it pulls a decent amount of air and virtually silent. Bump up to high speed with the fans in parallel and it moves some air. The fans are 16" Flexalite 3,000 cfm units and the radiator has a 34x19" core. I mounted the relays to the firewall behind where the oil fill tubes and dipsticks sit. The new AN power steering lines and the PS cooler clear everything with plenty of room to spare.

[Linked Image][Linked Image][Linked Image][Linked Image]

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Posted By: shaggy Re: 1997 Chevy Express Cobra Conversion - July 10th 2021 10:26 am
My van came out of Elkhart too but then I think 90% of american RVs and campervans were made there at one point. I think it was a menonite town.

Brochure I have says cobra was an Odyssey company and was on county road 3 south, elkhart.
Probably the company was sold to Advantage in the 80s.

[Linked Image from live.staticflickr.com]cobravancatalogue by shagedemus, on Flickr
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - July 10th 2021 11:10 am
Nice progress. Cool Retro pics,
Posted By: frscke1 Re: 1997 Chevy Express Cobra Conversion - July 10th 2021 6:39 pm
Oh for shame Shaggy that pic is of a Ford Cobra van .... they gave you the wrong brochure .. lol
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - July 10th 2021 7:01 pm
Wow ! I was so focused on the interior I missed the white elephant in the room. smile
Posted By: shaggy Re: 1997 Chevy Express Cobra Conversion - July 10th 2021 9:01 pm
They mainly converted Fords and Dodge vans, seems like my Chevy one is a rarity. I have two different Cobra catalogues from the late 70s.
Posted By: frscke1 Re: 1997 Chevy Express Cobra Conversion - July 10th 2021 9:22 pm
Im just messing with ya ..... lol

And a rare one it is ... Ive never seen one


Sry I hijacked your thread '83G im done
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 12th 2021 3:14 pm
Originally Posted by frscke1
Im just messing with ya ..... lol

And a rare one it is ... Ive never seen one


Sry I hijacked your thread '83G im done

No worries. Just staying moving on this project. Picked up a parallel flow condenser with a lifetime warranty. With my discount at work it was under $80. The old style serpentine condenser (2 tubes snake all the way through it) was 2x the thickness and highly restrictive to airflow after nearly 25 years even though I had previously cleaned it and straightened the fins. The new parallel flow is thinner and being new and clean flows alot more air through it. Condenser design and function has been drastically improved in the 30 years since GM designed that early R134a condenser. The newer condensers typically reduce the a/c head pressure, let the a/c function better and help keep the engine cooler with the improved airflow.

[Linked Image]

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 12th 2021 4:36 pm
Harness is installed and works well. Only need to lengthen the two control wires and route them to the PCM inside the engine harness. The PCM will be controlling the fans based off coolant temp and a/c pressure. I am adding a GM a/c pressure transducer to the a/c discharge hose between the compressor and condenser. I tested the fans on video. First on low speed with the motors in series for 6 volts each. Then on high speed with the fans in parallel and 12 volts each. Fans draw 9.25 amps on low and 37 amps on high. The startup amperage spike is also very low with this wiring arrangement. The PCM will also run the fans only as much as needed so less wasted energy. With the PCM controlling the fans I can adjust the idle airflow when the fans turn on and off to maintain a steady idle speed. The PCM is also going to control the alternator when I am done with the wiring changes which means stable voltage as the fans turn on and off. I am going to try to bend the trans cooler mounting bracket in toward the condenser to get more airflow through it. It sticks out close over 2" from the condenser now because the condenser is thinner. Even so the airflow through the trans cooler will still pull a paper towel against it on low speed and hold it in place. But with the 2,800 rpm stall converter its hard to go overkill on trans cooling.

[Linked Image][Linked Image][Linked Image][Linked Image]

https://youtu.be/VavjEubOni4

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Posted By: newkirkinc1 Re: 1997 Chevy Express Cobra Conversion - July 12th 2021 10:26 pm
Looks great and nice work.
Posted By: kursed Re: 1997 Chevy Express Cobra Conversion - July 14th 2021 2:17 am
Looking good man.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 15th 2021 3:55 am
Thanks guys! I rigged up a solid coolant recovery tank. One for a 95-99 OBS truck fit well and mounted with some left over brackets from an OBS Flexalite fan bracket kit.

Also started prototyping the airbox heatshield for the large 4" diesel air filter I will be using.

[Linked Image][Linked Image][Linked Image]

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - August 11th 2021 3:21 am
So I finally got around to dropping the 383 in. Still have alot of work to do but the engine is finally bolted backin.

[Linked Image][Linked Image][Linked Image]

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Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - August 11th 2021 5:30 am
Nice,
Posted By: newkirkinc1 Re: 1997 Chevy Express Cobra Conversion - August 11th 2021 1:45 pm
Very nice and clean.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - October 05th 2021 4:44 am
Since I have last updated, I was promoted to a store manager at work. New manager training and the duties of running a store have consumed alot of my free time. Still trying to get to the shop a few times a week for a couple of hours each visit. I have the engine back together, the headers on and the exhaust connected. Tonight I poured 5 gallons of fresh 93 octane in the empty tank. I cycled the key a couple of times to build up fuel pressure to check for leaks. Pulled the crank sensor connector and cranked it over enough to get the oil pressure up after months of sitting, did not take long to show 40 psi on the factory gauge. Connected the crank sensor, turned it over and it fired in about 1/2 turn. Definately needs some tuning, but it runs and it is healthy! Let it run for about 45 seconds. Wish I had thought to take some update pictures and a video clip. Still have to install the core support, plumb the radiator, finish the trans cooler lines (currently a 8" piece of hose connecting the cooler ports on the trans) and a few other details. Before I get it back on the road, I have to go over every suspension bolt and nut with a torque wrench, bleed the brakes, hookup and leak test the power steering, vacuum down and charge the a/c, and take it for an alignment. Making forward progress albeit slowly.
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - October 05th 2021 2:12 pm
Congrats on the promotion. Sounds like the build is going great. A video pic of the motor running would be great, chevy
Posted By: Rusty Pancelode Re: 1997 Chevy Express Cobra Conversion - October 05th 2021 4:09 pm
Cool.
Sounds like some good progress.
Posted By: Joeman Re: 1997 Chevy Express Cobra Conversion - October 10th 2021 1:24 am
Wow, that's sweet! Congrats on some amazing work!
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - October 18th 2021 5:23 am
Startup of the 383 in the Express with the factory L31 based manifold and ignition, running on a Green/Blue P59 out of a 2004 DBC 6.0L van. So far I have segment swapped the 4L85E, turned the VATS off, set the injector flow rate to match the AUS Injection 48 lb/hr spider and copied the MAF table from a 2002 L31 van into the 2005 Mexican tune. Had to populate the idle tables that were not used with the manual trans. Other than that the mexican cal is relatively stock GM issue. Ran it on the old 0411 the other day.

https://youtu.be/FzEDpuSIwJc
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - October 18th 2021 10:03 am
Brother that sounds and looks clean. Thanks for the video. chevy
Posted By: Dyno_Dave Re: 1997 Chevy Express Cobra Conversion - October 18th 2021 2:36 pm
Nice work!

I've often though that a GM 383 replacement for my L31 would be nice. But the old L31 just keeps running so nice, I don't see it happening until it dies.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - October 23rd 2021 5:42 am
Hooked up the exhaust, topped off the cooling system and let it run long enough to get up to full temp with the closed loop enabled. Pulling about 10-15% on the long terms. Still have the cutouts open and need to hook them up again. Tamed down alot in closed loop.  Also disabled the catalyst warmup spark retard.

https://youtu.be/FPEuk8hibPg
Posted By: newkirkinc1 Re: 1997 Chevy Express Cobra Conversion - October 23rd 2021 2:02 pm
Great work!
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - October 25th 2021 1:47 am
Hooked up a water hose to the heater return on the water pump and dumped the waste water out of the shop to really get all the heater core, and lines really flushed out today. Got it dialed in pretty good after adding a 4" MAF into the mixture. Also figured out the bog off-idle when first starting to open the throttle. Transmission abuse mode was kicking in even in Park and cutting the ignition timing to negative 15 or 15 after top dead center. Disabled abuse mode and it rips now. Its taken on some nice exhaust crackle and popping going into decel fuel cut as well. On throttle snap up to fuel kill at 5,200 it leaps up the RPM band. To hit the air/fuel ratio target the MAF is reading 410 gms/sec at 5,200 rpm. Given the formula of 1 gm/sec is 1.2 hp, that means I am feeding it 492 hp worth of fuel. Predicted torque on the torque model is reaching 512 ft/lbs at about 3,700 rpm. The cyl/air reading holds pretty flat at 1.03-1.09 gms/cyl from about 3,000-5,200. It is moving a ton of air through the engine and the exhaust just booms because of it.

https://youtu.be/iEn1Ht6Ta-s

https://youtu.be/1xXFPoS3Y2Y
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - October 25th 2021 3:14 am
So nice.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - November 14th 2021 2:00 am
Originally Posted by SDMickey
So nice.
Thank You!
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - November 14th 2021 2:00 am
Been playing around with the tuning and finally decided it was safe to crank up the RPM.  Engine has seen 6,500 rpm with the carb.  Have the fuel kill set at 6,200 now in the tune.  Absolutely rips up the rpm range.

https://youtu.be/J4v4Z9rAKio
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - November 14th 2021 6:23 am
Sounds nice,
Posted By: kursed Re: 1997 Chevy Express Cobra Conversion - November 14th 2021 12:37 pm
Heck yeah, clean sweep.
Posted By: newkirkinc1 Re: 1997 Chevy Express Cobra Conversion - November 14th 2021 2:00 pm
Awesome!
Posted By: Dyno_Dave Re: 1997 Chevy Express Cobra Conversion - November 15th 2021 4:36 pm
Sounds very healthy!
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - November 20th 2021 1:03 am
Pulling crazy airflow in through the MAF. ~425 gms/sec at 5,600-5,700 rpm and still over 410 at 6,200. About 500-510 hp worth of air and fuel getting to it. Safe to say it is going to be healthy once I finally get it back on the road.
Posted By: 1986LSVAN LS swap into 1986 G20 Van - December 28th 2021 9:38 pm
Purchased new by my late folks. First several years spent on west coast in Washington. Was given to me when folks felt it was getting less dependable. Wife and I camped around Alaska for a several years until engine was so weak it was scary to take very far. I could not stand the idea of junking it, and when looking at new ones I got scared off by the multiple big screen TVs and such (we don't camp to watch TV). Decided to buy a running LS engine from junkyard and fix it up. I figured if I found expected rust I would stop and throw the engine in a pick-up or something. To my surprise, I only found rust under the original battery location, so pushed on with the swap. I am not gifted at mechanics, but I am good at cleaning stuff, which seems like 90% of the task. Wasn't even sure it was a possible swap but kept chasing issues down until I convinced myself it was possible. The original 305 engine was a dog when it was new and was about 145 HP and mileage was very poor. The LS engine more than doubles the power(300+HP) and will hopefully be a big improvement in mileage. I felt the high torque of the LS truck engine coupled with the .7 overdrive ratio would give us a decent highway cruiser.[Linked Image]


Description: Ugly undercoating everywhere
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Description: Original battery location
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Description: New PCM mounts in old battery location
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Description: Old AC location
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Description: Holes for new gauges
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Description: New tach and trans temp gauges
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Description: Old tire carrier
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Description: old ladder
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Description: Before accent stripe repaint
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Description: After stripe repaint
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Posted By: lukester Re: LS swap into 1986 G20 Van - December 29th 2021 12:36 am
Awesome man. I hope the swap goes smoothly.
Posted By: newkirkinc1 Re: LS swap into 1986 G20 Van - December 29th 2021 12:51 am
Good luck with the swap!
Posted By: 1986LSVAN Re: LS swap into 1986 G20 Van - December 29th 2021 1:14 am
I have been accused of 'polishing a turd' on this project.....you rarely see camper vans at car shows. A few more pics.


Description: Dirty Donor engine
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Description: cleaned LS
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Description: LS inserted
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Description: from the doghouse
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Description: AC out heater only in
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Description: PCM TAC bracket
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Description: dirty engine bay
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Description: clean painted engine bay
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Description: new Mishimoto radiator
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Posted By: 1986LSVAN Re: LS swap into 1986 G20 Van - December 29th 2021 1:31 am
Thanks Lukestar and Newkirkinc1, encouragement appreciated. I am really enjoying sharing my project with folks that might actually be interested in what I am trying to do.
Posted By: lukester Re: LS swap into 1986 G20 Van - December 29th 2021 3:38 am
Yeah man keep those updates coming.
Posted By: SDMickey Re: LS swap into 1986 G20 Van - December 29th 2021 6:02 am
Ditto. Sharing our experiences help everyone, Clean work and your are doing your Van justice,
Posted By: soundhd Re: LS swap into 1986 G20 Van - December 29th 2021 10:37 pm
I'm sure there are others like myself on this web site that wish we could have an LS motor in ours.......looks good.
Posted By: 1983G20Van Re: LS swap into 1986 G20 Van - January 02nd 2022 7:36 pm
Originally Posted by SDMickey
Ditto. Sharing our experiences help everyone, Clean work and your are doing your Van justice,
Not a fan of less than a 6.0L. I would take a 5.7L vortec with a little work over a 6.0L even. Low-end torque is not a LS engines strong suit, especially a 5.3L or smaller. With that much of a raised roof, need lots of low rpm torque like a 383, 454 or 8.1 would make to cruise along in overdrive. 4L60E is also not going to be very happy pulling that around. Suggest atleast at the minimun a deep pan, big cooler after the radiator cooler and maybe a shift kit with 2nd and 4th gear billet servos from Sonnax. Would also swap to a 4.30 rear gear if its a 5.3L. Even though they only made 165ish hp a stock 305 made good low-speed torque with peak torque down at 2,000 rpm. Mine woke up alot with a performer rpm intake, thorley tri-ys, rejetted and tweaked Q-Jet and a performance oriented distributor recurve. Was really good on fuel with the 700r4 and 3.08 gears.

Also even though I liked the look of the older individual gauges, I swapped my 83 to the newer style open dash bezel. Really made the gauges easier to read at a glance. 91+ used an electric speedo.
Posted By: frscke1 Re: LS swap into 1986 G20 Van - January 02nd 2022 8:48 pm
After you cook your tranny replace with a 4L80E, my 454's have beat mine and they still ask for more abuse ....

I have 4L80E's in both my vans and recommend them to any body !

'92 454 4L80E 4.10 on 245 tires

'93 454 4L80E np205 4.56 ft & rear on 315 tires

They are both fun and both take a lickin ...
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - January 03rd 2022 4:06 am
Been over a month since I was at the shop. Between being short staffed, people taking vacation, a couple of covid cases and an injury on the job, as a manager been too dang busy to stop from work. Also taken a day off work and had my free time occupied helping my mom recover from rotator cup shoulder surgery. Finally got over to the shop in time for it to be 19°F outside and 45°F inside. Worked on the Express some and then cold started and ran it for a while. Good to hear her run today though. Even though I have not even touched the cold start tuning in 45°F after sleeping more than a month, it started and ran well.

https://youtu.be/2Ydppg2TtQU

With the 3" electric cutouts open the 383 cold idles like a dang Sherman tank!!!
https://youtu.be/fdiwYVWuxm8

I love the way a WW2 tank sounds on startup BTW!
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - January 04th 2022 5:09 am
Man that sounds nice. Hope your Mom get well soon. I can relate to being short staffed at my job as well.
Posted By: frscke1 Re: 1997 Chevy Express Cobra Conversion - January 19th 2022 11:22 pm
Here is another van on here ... Id like to see the 2 of you line up ...

https://www.vanning.com/threads/ubb...at-milan-mi-friday-night.html#Post634421
Posted By: Lee7673 Re: 1997 Chevy Express Cobra Conversion - January 20th 2022 2:02 pm
This is really coming together. Nice work
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - April 15th 2022 2:01 pm
Have been slowly working on it. Managed to get the new muffler and tailpipe fit yesterday afternoon. Snagged a Walker Quietflow SS and matching 4" tailpipe for a 2001-2006 3500HD with a 6.0L or 8.1L from Summits scratch and dent clearence area. Fit the 97 Van like it was made for it. Muffler is dual 3" in, single 3" out and the tailpipe is 4" but necks down to 3 where it slides into the muffler.

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https://youtu.be/zJBiw3xkiYY

https://youtu.be/bq8CAvqnubU

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Posted By: lukester Re: 1997 Chevy Express Cobra Conversion - April 16th 2022 3:50 am
Nice
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - April 17th 2022 1:10 am
Nice work
Posted By: SafariTim Re: 1997 Chevy Express Cobra Conversion - April 17th 2022 11:36 am
Just caught up on the van. Awesome work! I installed the same head unit in my 05 Safari. Had to move everything from around the dash. It was alot of work but I loved it. Sold the van but kept the head unit and dash trim to put into my 98 astro. [Linked Image]
Was thinking about putting in the Express. But not sure if I want to do it the same as I did the first time. I hate have to take that whole dash panel off every time I need to get in there. Dont want to say it, but I like the way Ford radios come out.

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Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - July 15th 2022 2:25 pm
Made alot of headway and it is driveable now. After street tuning I dialed in the 383 on a chassis dyno. It made 383 hp and 399 tq uncorrected and 412 hp and 431 tq std corrected on a 102F day. Peak torque happened at 3,100 rpm and peak hp was 5,600. I need to change the fuel pump so that I can dial it in on E85, its begging for higher octane and more timing. I made peak power with a very conservative advance curve and 91 octane.

I flushed the ac system, changed the compressor to a Sanden 4261, swapped in a parallel flow replacement condenser and went with a variable orifice tube up front from Rockauto. I added a PCM controlled 16" 3,000 cfm puller and a cutdown Duramax fan on a Trailblazer SS thermal fan clutch. Went back to a stock radiator and an 01-02 fan shroud. Really made everything fit better. Using a factory 01+ Donaldson designed GM air cleaner housing and it is plumbed with a 4" intake and 102mm cartridge style LS3/LS7 MAF. I get 41°F air out of the left vent at idle in 102F temps and the engine stays around 185°F. I recently updated the fan clutch to an electronically controlled clutch. The clutch fan is on the PCM fan 2 output via a relay that supplies it 12v. When the engine first starts and the interior is hot the fan clutch locks up and really drops the ac pressures, then as the interior cools down and the pressures drop the mechanical fan returns back to the lower rpm setting. If it warms up to 189F the clutch is locked in. It usually holds around 185F with the clutch released and the 3,000 cfm electric on.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - August 02nd 2022 3:46 pm
Currently waiting on an all aluminum replacement radiator from California. To replace the almost new TYC OE replacement thats core exploded. I installed my all NOS GM headlights, turn signals, side markers and reflectors up front along with finished my exterior LED conversion. Including the headlights and all exterior lights except the turn signals and brake lights that are a momentary use the exterior lighting draws 4.7 amps. 4 HI headlight mod incuded for extra light. Now on to the customizing the Kodiak K&N heatshield so that it clears the hood.

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Posted By: SafariTim Re: 1997 Chevy Express Cobra Conversion - August 02nd 2022 10:19 pm
Yes, Sir. What he said was,
You cant spell Express without SS.
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - August 03rd 2022 4:30 am
lol
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - August 03rd 2022 4:32 am
Originally Posted by SafariTim
Yes, Sir. What he said was,
You cant spell Express without SS.

Thanks Tim,

Hopefully everything is good on Sodor Island for Gordon and you.
Posted By: SafariTim Re: 1997 Chevy Express Cobra Conversion - August 03rd 2022 10:28 am
Yes sir, This fat conductor is pleased.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - August 07th 2022 2:26 pm
The nearly new TYC radiator failed, put an all aluminum unit in. The 383 is running cooler. Ran it for a solid hour to get all the air out with the front end jacked up. It took a solid 30 minutes of run time before it stopped venting a steady stream of air bubbles.


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While I had it running could not resist catching a video clip of the exhaust sound of the sweet 383 at idle.
[url=https://youtube.com/shorts/T29nCd8sifQ?feature=share]


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Posted By: frscke1 Re: 1997 Chevy Express Cobra Conversion - August 07th 2022 5:52 pm
I did the same thing for my '93 and my 454 LOVES IT !...

Alum rad WAY NICE thing to do for your van.

I had a double dual row made with Oil Coolers .. cost a little more than $220. Sent them my dead radaitor .

[Linked Image from live.staticflickr.com][Linked Image from live.staticflickr.com]
[Linked Image from live.staticflickr.com]
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - August 08th 2022 4:03 am
Nice
Posted By: DaveT Re: 1997 Chevy Express Cobra Conversion - August 12th 2022 4:33 am
Wow, that is nice
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - August 12th 2022 3:31 pm
That is a nice radiator.

I have done some more work on the van. My ac vents have been blowing a bit weak up front. I found 2 foam seals missing on the HVAC case. They were there when I changed the evaporator in 2011. I can only assume the foam seals dried up, fell apart and blew away. Since I had to open the underhood evaporator box to change them, I went ahead and cleaned the evaporator core screen and changed the blower from a 11 year old aftermarket to a new GM. Since I had to recover the refrigerant to access the core I had to vacuum and recharge the system. The front vents blow twice as hard now and cold air is no longer blowing under the hood. I played with the refrigerant charge a bit. I then tested the ac in 90°F and 70% humidity.

With both blowers on high speed and recirculate up front (rear always recirculates), I let it idle at 750 rpm for 10 minutes. After 5 minutes the front center vents were at 50°F. The rear were at 53°F at the end of the run. In the first 5 minutes, the pressures were 228.5 psi and 37.5 psi, compressor outlet was at 180°F, the compressor inlet was 54.6°F, the pressures of the gas indicating an evaporator refrigerant temp of 47.6°F and a condensing temperature of 148°F.

I moved the temperature probes to the evaporator suction line and the liquid line ahead of the orifice tube. At 10 minutes, the front was down to 46°F at the vents and the rear was down to 50°F. The rear vent I tested has close to a 15 ft run of air ducting up the driverside wall, across the roof in the back and all the way up to the mid row. The pressures were down to 219.7 psi and 35.5 psi. That corresponds to a refrigerant temp in the evaporator of 45.7°F and a condensing temperature of 145°F. The probes were measuring 52.6°F on the suction outlet and 112°F on the liquid line. Makes for 6.9° superheat and 33°F subcooling.

The suction probe had alot of heat radiating on to it from the headers and the engine fan was blowing hot air across it as well so likely skewed a few degrees warmer than the actual tubes temperature. I moved the probe 3 times just to see where the temps on the low side were. There was less than 2°F difference between the cold liquid line, the evaporator suction line and the accumulator suction outlet with an OEM accumulator blacket and insulated suction line. The compressor return was 5-6°F warmer than the evaporator outlet.

I then commanded 1,500 rpm idle using HP Tuners but the IAC was limited to 1,150 rpm. About 2 minutes into the 1,150 rpm test the front vent was down to 42°F. The rear vent was 45°F. The low side pressure was down to 30 psi and the high side was 226.8 psi. Corresponding to a 39.4°F evaporation temp and a 147°F condensing temp. The clamp on the liquid line was showing 114°F and the evaporator suction line 48°F. The low side temp probe and pressures were still dropping, but at that instant it was 8.6°F superheat and 32°F subcooling. I ran it like that for a total of 10 minutes.

After 10 minutes at 1,150 rpm the low side pressure was at 28.8 psi and the high side was at 227.2 psi. Corresponding to an evaporation temperature of 38.3°F and a condensing temperature of 147°F. The probes were 47°F and 115°F. Giving a superheat of 8.7°F and a sub cooling of 32°F. I moved the hot side temperature probe once again back to the compressor.

After 5 more minutes the compressor reading had stabilized to 163°F. The pressures had also changed slightly. The low side was down to 28.3 psi and the high side was 227.8 psi. The evaporation temp 37.6°F and the condensing temp was 148°F. The front vent was down to 38°F, the rear was 42°F.

I learned alot about how these ac systems function from the measurements I took.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - August 12th 2022 4:48 pm
https://youtube.com/shorts/-WukKhjkckg?feature=share

https://youtube.com/shorts/4Ok9s8cMM2Y?feature=share
Posted By: kursed Re: 1997 Chevy Express Cobra Conversion - August 12th 2022 10:14 pm
Cool! No pun intended... well maybe a little pun intended. lol
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - August 29th 2022 2:49 am
Vanula escaped from the laboratory for a while today. First time I have driven it in several weeks. Actually remembered to take a picture of it today. Everytime I drive this I forget how much I have always enjoyed driving it. Its alot more fun to drive now. It corners with very little body roll, accelerates like a 60s muscle car and also stops very well for its weight. The steering is tight and responsive like it was new.

[Linked Image]

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Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - August 29th 2022 3:41 am
Wow ! Nice build
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - September 11th 2022 7:44 pm
As I have been putting a few miles on it, have found a couple of small things to address. One of the AN cooler lines to the auxiliary trans cooler was leaking fluid, had to remove the grille to get to it. Also had a head bolt that started seeping coolant once I was able to get the system to fully pressurize. Had to remove the engine cover and luckily it was an easy head bolt to get to. Other than that it is running great.
Posted By: SafariTim Re: 1997 Chevy Express Cobra Conversion - September 16th 2022 1:28 am
Originally Posted by 1983G20Van
Vanula escaped from the laboratory for a while today. First time I have driven it in several weeks. Actually remembered to take a picture of it today. Everytime I drive this I forget how much I have always enjoyed driving it. Its alot more fun to drive now. It corners with very little body roll, accelerates like a 60s muscle car and also stops very well for its weight. The steering is tight and responsive like it was new.

[Linked Image]
Looking good! What size tires are they? Is it that the tires are big or the front is that low? The front wheel well looks nice and full, mine has so much gap.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - October 04th 2022 9:40 pm
Originally Posted by SafariTim
Originally Posted by 1983G20Van
Vanula escaped from the laboratory for a while today. First time I have driven it in several weeks. Actually remembered to take a picture of it today. Everytime I drive this I forget how much I have always enjoyed driving it. Its alot more fun to drive now. It corners with very little body roll, accelerates like a 60s muscle car and also stops very well for its weight. The steering is tight and responsive like it was new.

[Linked Image]
Looking good! What size tires are they? Is it that the tires are big or the front is that low? The front wheel well looks nice and full, mine has so much gap.

The tires were just some old ones that came with those wheels. They were 235/85R16s and they did rub in tight cornering.

I bought 5 new take off Bridgestone L265s in LT245/75R16 along with a spare steel wheel for $918 out the door. The tires were ao new they still had the molding fuzzies on the tread.

See if you can spot the tire shops mistake... Before reading the next sentences.


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I did not pay close enough attention when they went on and had to later swap the front wheels and tires side to side. I had never noticed that while the tires are not directional my wheels are. There are 2 of one and 2 of the other.

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Posted By: frscke1 Re: 1997 Chevy Express Cobra Conversion - October 04th 2022 9:54 pm
Originally Posted by 1983G20Van
The tires were ao new they still had the molding fuzzies on the tread.


Tires 10 yrs old can still have the little fuzzies on them. What is the DOT date and did you get a matched set ? All made at the same time.
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - October 04th 2022 9:55 pm
New GM front blower motor has the ac blowing strongly.
https://youtube.com/shorts/SI7SDd-ZoRE?feature=share

I have made some additional tuning changes and have the envine running like a refined machine now. On a 250 mile nearly all highway trip with the cruise set at 70-80 mph where traffic permited I managed 18.8 mpg. I love the torque the 383 makes. On a 2 mile long 6-8% grade I go up fairly regularly, with the cruise set at 80 mph, it did drop to 76 mph but it just climbed without downshifting or unlocking the torque converter.

https://youtube.com/shorts/VSfSVm6tG3k?feature=share

For reference this is the first part of the grade I mentioned, cruising along in my mom's Titan. That truck is geared so tall it makes it all of 100ft before it downshifts.

https://youtube.com/shorts/0G_JirYtj0o?feature=share
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - October 04th 2022 9:56 pm
Originally Posted by frscke1
Originally Posted by 1983G20Van
The tires were ao new they still had the molding fuzzies on the tread.


Tires 10 yrs old can still have the little fuzzies on them. What is the DOT date and did you get a matched set ? All made at the same time.

Tires are a matched set and they have this years DOT date (04/22).
Posted By: 1983G20Van Re: 1997 Chevy Express Cobra Conversion - October 17th 2022 6:44 am
Van has been running well, but it is about to go under the knife yet again. At WOT I have always seen the intake manifold pressure dropping as the engine revs up. I turned the MAF sensor off in the PCM calibration and started pulling apart the air intake. First the air cleaner. Then the MAF. Then finally the dumb intake hat that GM used to literally cram our engines into these vans. I temporarily installed the marine flame arrestor that is little more than a mesh screen on top of the throttle body. With the throttle body finally able to draw in air, the manifold pressure went from 88 KPA to 97 KPA at 5,500-6,000 rpm. The engine ran like it has never run before. I would say it probably gained 40-50 HP. That pressure difference observed at the manifold is equivalent to driving at 4,000 ft elevation. I found an intake manifold that I ordered with fuel rails. It will have a 102mm LS style throttle body on the front of it, connected to the 4" silicone inlet ducting and 100mm MAF. The manifold is only 90mm at the face but I already have a 102mm LS style throttle body and a matching 102mm to 90mm adapter laying around unused on a shelf at the shop that came on a LS intake I put the DBW throttle body back on. My 97 Express van has 11" of height between the china wall at the end of the engine block and the bottom of the engine tunnel under the wiper cowls. The upper plenum sits 8" off the china wall and the lip for the throttle body mounting is 9" off the china wall. It will clear both the engine tunnel on the body and the factory doghouse. It is similar to the GM Ramjet manifold. I found engine dyno data for both the Ramjet and the L31 Marine crossram manifold on the same long block. Both the Ramjet and 300 HP Marine engine use the same short block, same 9.1:1 compression ratio with their thicker head gaskets, as well as the 196/206@ 0.050 duration GM 395' camshaft. The Ramjet and Marine intake both make the same torque at 2,500 rpm. At 2,700 rpm the Ramjet intake with its 4" long runners and open plenum starts to pull ahead. By 4,800 rpm the Ramjet 350 is up 61 hp over the marine intake. This manifold has slightly longer runners at 6" long. It should make a little more torque than the Ramjet manifold. That being said a 9.1:1 350 with a Ramjet manifold is already making 390 ft/lbs of torque at 2,500 rpm. With 383 cubic inches of air hungry small block compressing that air to a 9:1 dynamic compression ratio, I do not see this manifold making any less torque than the ported truck manifold or marine manifold. If it does cost a little torque, it will be well under the 2,800 rpm stall speed of my torque converter and a mere touch of the throttle will make the torque loss vanish. I am a little worried about how twitchy the throttle will become with the 102mm throttle body. The 80mm that is currently on the van is already pretty touchy at lower speeds.

The terrible flowing intake hat. I think this part alone is solely responsible for the 10 hp loss both the 305 and 350 in the Express vans have compared to the same engine in a truck.
[Linked Image]

Casting appears to be very clean in the pictures. Will know more about the quality of the manifold when it is in my hands.

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Posted By: SafariTim Re: 1997 Chevy Express Cobra Conversion - October 17th 2022 8:32 pm
Oh wow!
Posted By: Astrocreep66 Re: 1997 Chevy Express Cobra Conversion - October 19th 2022 12:07 pm
Bitchin' intake.
Posted By: SDMickey Re: 1997 Chevy Express Cobra Conversion - October 20th 2022 4:19 am
Ditto !
Posted By: newkirkinc1 Re: 1997 Chevy Express Cobra Conversion - October 20th 2022 10:27 am
Sweet!!!!!!!!
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