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Dumb question about improving gas mileage
#295509 May 28th 2009 12:52 pm
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I just got a 1977 Dodge B200 Tradesman. Right now, it gets about 8.3 miles per gallon (highway). Besides rebuilding the carb, and all the small things like keeping tires inflated, using the right oil, etc., what can I do mechanically to improve it?


- Pete
vanlivin.com
Re: Dumb question about improving gas mileage
peterparker523 #295533 May 28th 2009 1:20 pm
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8.3 MPG highway is pretty bad for a van. Here is what I would recommend, and most of it is pretty cheap.

Give your van a good tune-up. Use Napa gold brand filters.
Gap the plugs to .045.
Switch your ignition system to HEI but keep your stock distributor. HEI will give you a hotter spark and better dwell control at higher RPM.
Recurve the spark advance curve in your distirbutor. Vans need slow advance curves due to their weight.
Rig up a cold air intake. Look at how it was done on mid 80s era vans and copy it (hint- use the air cleaner off a mid 80s van and grab the piece that mounts on top of the radiator support and the hose).
Make sure the heated air intake system on the van is hooked up and functional.
Check your choke pulloff and vacuum advance diaphragm for leaks.
Check for vacuum leaks in general.
Keep your transmission kickdown adjustred properly.
Remove the accumulator spring in the transmission and back the line pressure screw out until only two threads are left in the housing.
Rebuild the carb and make sure it is in good shape with everything set right and all hoses hooked up correctly.
Get a clutch fan off of a mid-80s van.
Keep the tires inflated to 35 PSI

Now the more expensive stuff.

Switch to an Edelbropck SP2P of Offenhauser Dual Port intake.
Use a Holley 4360 Economaster carb.
Swap your transmission to an A500 four speed overdrive automatic transmission (just make sure it isn't an electronically controlled one).
Aluminium driveshaft
Aluminium wheels
Mill the heads to increase compression.
Oversize exhaust with free flowing mufflers (I like Walker Quiet-Flow myself)
Swap rear axle gears to 3.5 or 3.2.
Aerodynamic body mods- fender flares to keep air out of wheel wells, fender skirts on the back, belly pan, air dam up front, air tabs/other rear mod to improve the air flow off the back of the van, ground effects/runningboards on the dies to keep air out from underneath the van
Low rolling resistance tires
Lighten up the van- do you really need to haul the cooler and the bed and three extra captains shairs with your everywhere you go?
Synthetic fluids in engine(5W-30 or 10W-30)/tranny/rear axle

If I think of more, I will add them.


Windows- they're what make a van worth owning!
Re: Dumb question about improving gas mileage
Reed #295546 May 28th 2009 1:42 pm
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Wow, Reed! How long were you waiting for someone to ask that question? lol Just joking with ya. Great answer tho!

About the only thing for me to add right now is taller rear tires. Easier than gears.


Ken Schwarz
Tricky Truckers, N.J.
Van Clan Plus One, Canada
Manse Vans, Finland
Rebel Vanners, N.J. "USA"
Toopa Sinner Tribe, N.C.

www.showvans.com

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Re: Dumb question about improving gas mileage
Superbeast #295566 May 28th 2009 2:04 pm
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Reed is the master of tuneups for mileage.Only thing I'd add is check over your stock dizzy when you're doing the tuneup.MoPar's are known to wear out the shaft bushings which lets the airgap between reluctor and pickup move closer/widen and that will kill mpg.Just see if you can move shaft side to side,any flex and replace the dizzy.If it's good check the gap,should be .008th I think,use a brass feeler gauge if you can as pickup is magnetized and can give a false "pull" if you use a steel gauge.
When you check the timing also see if there's any timing chain slop,do all of these things then drive it like you own it not like you stoled it.
shift


79 B300 4x4,80 B100,83 B150.If it's not a van I just don't understand it.
Re: Dumb question about improving gas mileage
SixShot #295570 May 28th 2009 2:16 pm
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8.3 ........DAMN!!!!!


VANTICIPATION LIVES,1977 3/4 ton chevy fullsize 4*4 !!! VANNIN,HUNTING,ROCK&ROll[Linked Image]LL
Re: Dumb question about improving gas mileage
vanticipation #295577 May 28th 2009 2:52 pm
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New Air Filter $9 - 14
PCV valve $2
Fuel Filter $3 -$5
$4 - Add some lucas or STP gas treatment to help clean up the carb.
clean up your chokes moving parts with carb cleaner.

this stuff is all real cheap.

You could do like reed said and get some kind of cold air/ram air going. I made one on my 83 chevy and it helped. This time around I have an open air element and headers so I'm going to add a functional hood scoop to get more air in there. That's custom and functional, so there are things to think about there. Free flowing muffler helps a lot.

Like ken said, taller tires (a good reason to get a new set of tires if you have to reason with the wife) you could get new wheels to go with those at the same time. You're making improvements and adding some custom touches. Thats' what I'm getting at.


I go to Truck-ins. How about you?
Re: Dumb question about improving gas mileage
Reed #295597 May 28th 2009 4:01 pm
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Man! Thanks Reed, and everyone else with ideas!


- Pete
vanlivin.com
Re: Dumb question about improving gas mileage
peterparker523 #295613 May 28th 2009 4:53 pm
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The reason why all this stuff comes quick to my mind is because I just went through it with my brother's 1983 Dodge shorty.

I got my brother's van with a 225/727 engine combination to get 20-21 MPG on the highway, empty. See here: http://www.slantsix.org/forum/viewtopic.php?t=30370&highlight=21+inches That is using all factory parts too, nothing fancy. I look forward to doing some more mods on it to get hopefully even better mileage.

My transmission, intake manifold, and carburetor choices assume you have a 318 or a 360 in your van as well. The key thing to remember with a van is that to get better gas mileage you have to build, tune, and gear for low RPM torque. Most performance parts are for car motors so they focus on the mid and high RPM ranges that our vans never see, even on the highway. The highest RPM my motors ever see is 4k, and that is doing 80 on the freeway.

If you want to switch the ignition to HEI, DON'T go buy the hundred+ dollar kits sold online and in catalogs. You can search the web for wiring diagrams to wire up the $20 module to your current distributor and save a bunch of money.

That was also a good call about the timing chain. Check the slack. The easy way is to pop the distributor cap and watch how many degrees you can turn the crank before the rotor moves. Anything more than 5 crank degrees and you need a new chain (tip- rotate the motor clockwise to take up slack, and then rotate it counter clockwise and watch for rotor movement).

I am always searching for ways to get better mileage out of vans. Gas is only going to get more expensive, and until I can save up enough to convert a van to run on electric then I want to maximize my fuel dollar.


Windows- they're what make a van worth owning!
Re: Dumb question about improving gas mileage
Reed #295623 May 28th 2009 5:07 pm
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Bad Girls from New York, Bad Western Inn in IN.
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My Red Flamingo gets better mileage the heavier she rides!
I know, it doesn't sound right at all does it!

And one I re-lived this past weekend--keep the windows up, especially going west!!! hee hee Way to much drag!

Suzie


Cherish your friends!
HUGGS to all!
Suzie
Re: Dumb question about improving gas mileage
Reed #295628 May 28th 2009 5:13 pm
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Wow Reed..why don't you come out here and dial my 85 in? lol


Nate Breece
Re: Dumb question about improving gas mileage
NateB #295633 May 28th 2009 5:32 pm
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Heh.


Windows- they're what make a van worth owning!
Re: Dumb question about improving gas mileage
Reed #295716 May 28th 2009 11:50 pm
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My mileage has worsened since developing exhaust leaks from every possible point that can leak before the cat, I assume it's affecting the O2 sensor readings. 9MPG city, 13-14 highway with a 3.9 but I'm not fixing any of them since I'm working on a 318, but if you have exhaust leaks try fixing them.


In search of the illusive prairie lobster
"If you dont stand behind our troops feel free to stand in front of them"
Re: Dumb question about improving gas mileage
vervepipes #295741 May 29th 2009 2:40 am
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Verve- Actually, I say fix the leaks AND replace the cats- most likely they are clogged and/or have failed internally causing excessive backpressure. Universal fit high-flow catalytic converters are reasonably priced these days. If you can afford it, go with 2 1/4 inch line all the way back and get some free flowing mufflers too.

I have heard the late 80s/early 90s Mopar TBI systems are terrible as well. You might actually do better mileage-wise with a carb.


Windows- they're what make a van worth owning!
Re: Dumb question about improving gas mileage
Reed #295792 May 29th 2009 11:43 am
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Reed, I don't have a 318 or 360, but a 400 big block, any changes to your advice? Thanks.


- Pete
vanlivin.com
Re: Dumb question about improving gas mileage
peterparker523 #295807 May 29th 2009 12:23 pm
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Wow, that makes it worse. Okay, what that really changes is my tranny recommendation. No automatic four speed with overdrive was ever offered for the big bloxk, so you are stuck with your stock 727. But you can still tweak it like i said- remove the accumulator spring, back out the line pressure screw.

I still recommend a Offy Dual-Port or Edelbrock SP2P intake, but for a carb I would say get a thermoquad or get an Edelbrock performer, 500 CFM with the electric choke. I would recommend the dual port over the SP2P however. You might still be able to get away with using the Holley 4360 carb, but it flows 450 CFM and is a spread bore carc. That might be too little air flow for a 400, but if you are building for low RPM torque it might do just fine.



Windows- they're what make a van worth owning!
Re: Dumb question about improving gas mileage
Reed #295843 May 29th 2009 3:02 pm
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Also, swapping to an "RV" cam or a cam designed for low RPM torque and HP would help.


Windows- they're what make a van worth owning!
Re: Dumb question about improving gas mileage
NateB #295855 May 29th 2009 4:02 pm
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now this question is for super beast. Just like putting a taller tire on the rear wouldn't that increase your gas mileage tremendously by itself? I mean then you would always be running downhill!


[Linked Image]
Re: Dumb question about improving gas mileage
G_ROLLER #295955 May 29th 2009 10:41 pm
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Is the a518 not an over drive version of the 727?


In search of the illusive prairie lobster
"If you dont stand behind our troops feel free to stand in front of them"
Re: Dumb question about improving gas mileage
vervepipes #295967 May 30th 2009 12:00 am
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Yes, it is, but there were no 518s made with the bolt pattern for a big block. Small blocks and big blocks have different bolt patterns on the transmission housings. A 400 is a big block, 273, 318, 340, 360, and 3.9 all share the same transmission bolt pattern. A factory adapter was made for a few years in the 60s to mate the slant six to the smallblock tranny, but no big block will bolt to a small block tranny.


Windows- they're what make a van worth owning!
Re: Dumb question about improving gas mileage
Reed #296494 June 01st 2009 9:26 am
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Good one G-roller! I guess that would be the case. lol

If the overdrive unit is a true 727 you could have the guts removed and swapped into your current 727 case. The internals of the cases are the same. The case bell housings were the only difference from what I know.

Unfortunately the 400 was always a gas hog. All the tips Reed suggested will help, but you prolly will never get better than 12 or 14 highway out of the big block without major work.


Ken Schwarz
Tricky Truckers, N.J.
Van Clan Plus One, Canada
Manse Vans, Finland
Rebel Vanners, N.J. "USA"
Toopa Sinner Tribe, N.C.

www.showvans.com

http://www.cardomain.com/ride/360991

[Linked Image]

"Coolness ALWAYS trumps comfort"
Re: Dumb question about improving gas mileage
Superbeast #296529 June 01st 2009 10:47 am
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The A518 is an A727 w/OD. The bellhousing is the same, but that's were the similarities end. The mid section and tailshaft of the A518 are completely different than an A727. It's physically a larger transmission.


Nate Breece
Re: Dumb question about improving gas mileage
NateB #296543 June 01st 2009 11:07 am
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Ditto what Nate said. Probably the bestthing you can do to help mileage would be change your rear gears. The 400 should have plenty of torque, so you could probably get away with a 3.2 rear axle gear ratio and be fine around town. Heck, my brother's 83 Dodge shorty has a slant six and it has 3.2 gears in the rear axle.


Windows- they're what make a van worth owning!
Re: Dumb question about improving gas mileage
Reed #296780 June 01st 2009 7:32 pm
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Keep in mind also, that a 400 of that vintage is a pretty low compression engine putting out probably around 170HP Net. Not much HP, but still has lots of torque.


Nate Breece
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