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Advice wanted- Building a 350 SBC for a G30
#792856 July 08th 2022 7:37 pm
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shaggy Offline OP
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So I recently lost cooling in my engine and the main bearings and crank are toast. mad

I've put that motor to the back of the workshop and bought a used engine....

Now the used motor I bought is a bit unusual in that it is a 1979 crate Target Master motor with only 13500 miles on it. It spent it's life in a fire engine at a regional airport.

It came with a holley street dominator intake, a holley carb, an oil cooler and Mallory unilite dizzy.

I intend to take the best from both motors to rebuild the Target Master into a reliable medium power 200-250 HP motor. It will spend it's life at reasonably low revs and hopefully will be run on propane mainly. I have a duel fuel system so can switch back and forth between propane and petrol.

A decent bit of torque would be nice but she is a big beast and it'll probably only ever see a max speed of 75 mph or so.

So my current plan is new main and con rod bearings, new rear main seal, cast alloy oil pan and rocker covers, Mocal Oil cooler, HEI dizzy, Dual plane Edelbrock performer inlet. Twin electric fans.

Some questions.

I presume the edelbrock performer is better in my application than the single plane Holley street dominator??????

Carb - Holley 4 barrell 600cfm or Edelbrock 1405?????

I have 462 heads on it now but have a spare pair of 882 heads should I switch for the 882s. Does the improvement warrant removing heads where there is no leaks?

The motor came with a TH400 but I have a TH350 in the van with a shift kit in it and it works fine. Am I right to stick with the TH350?

Anyone any tips on building a motor for torque rather than horsepower?
Any tips on building for running on propane, ( I'm gonna buy a Flashlube system to stop valve seat recession).

Last edited by shaggy; July 08th 2022 8:09 pm.

79 chevy G30 cobra camper conversion.
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Re: Advice wanted- Building a 350 SBC for a G30
shaggy #793069 July 16th 2022 4:08 pm
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Originally Posted by shaggy
I presume the edelbrock performer is better in my application than the single plane Holley street dominator??????

Edelbrock perfomer intake would work great, but the Holley would do fine as well, but the dual plane will be more streetable intake of the two choices.

Originally Posted by shaggy
Carb - Holley 4 barrell 600cfm or Edelbrock 1405?????

Holley hands down. I've been working on and rebuilding carbs since I was around 10 years old, and am now 43. I've had experience with everything from Weber, to Rochester, Holley, Edelbrock, Carter, Mikuni, Keihin, and even Solex. 90% of the Edelbrock carbs I've dealt with have a horrible problem with bogging down off the line at wide open throttle (mainly seen during drag racing), and it has a lot to do with the accelerator pumps. Just avoid them and save yourself the hassle of dealing with them. Holley is quite a bit simpler to work on and tune compared to Edelbrock as well.

Originally Posted by shaggy
I have 462 heads on it now but have a spare pair of 882 heads should I switch for the 882s. Does the improvement warrant removing heads where there is no leaks?

This guy is VERY knowledgeable on engine performance and this video is very informative about head performance. I personally wouldn't worry about it unless I were racing. For a street van, I'd just leave the heads on if there aren't any issues.

Originally Posted by shaggy
The motor came with a TH400 but I have a TH350 in the van with a shift kit in it and it works fine. Am I right to stick with the TH350?

I would stick with the th350 if it's working fine.

Originally Posted by shaggy
Anyone any tips on building a motor for torque rather than horsepower?
Any tips on building for running on propane, ( I'm gonna buy a Flashlube system to stop valve seat recession).

This one would be WAY too long of an explanation and lots of the stuff would be debatable. I've seen some engines running on propane, but I guess a lot of that depends on your prices and availability of the propane, plus the cost involved in converting to it.


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Re: Advice wanted- Building a 350 SBC for a G30
shaggy #793100 July 17th 2022 6:41 am
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shaggy Offline OP
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Thanks so much for the great reply Kursed.

I have since pulled the 462 heads as the motor wasn't turning over.
I found rust in the bores and 2 in particular were bad. I have the block with the machine shop for checking now and hopefully will know soon if if needs boring or if a hone will save it.

So when I get it back from the machine shop it will get new cam and crank bearings,new lifters, seals and gaskets all round, Holley carb on Edelbrock intake and a set of Hedman headers.
Possibly new pistons and rings too depending on what the machine shop say.

I'm gonna switch to the 882 heads seeing as the 462 ones are off now anyway.

Thinking about maybe getting roller rockers too.

Regarding Propane I already have a twin tank system in the van that is switchable between propane and petrol. I'm more looking at what can be done to make it run better on propane while still running well on petrol when I need it. I've been looking at ignition control modules that adjust the ignition timing when you switch over to propane. But I have to figure out how that would work with the MSD 1602 unit I have in her.

Quote
This guy is VERY knowledgeable on engine performance and this video is very informative about head performance.
No video link attached???

Thanks again for your help on this, it's very much appreciated.

Last edited by shaggy; July 17th 2022 6:44 am.

79 chevy G30 cobra camper conversion.
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Re: Advice wanted- Building a 350 SBC for a G30
shaggy #793141 July 18th 2022 10:48 am
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Originally Posted by shaggy
Quote
This guy is VERY knowledgeable on engine performance and this video is very informative about head performance.
No video link attached???

Thanks again for your help on this, it's very much appreciated.

DOH! Here you go. I highly suggest watching this guys videos as he is very knowledgeable on engine rebuilding and very informative.



[Linked Image from live.staticflickr.com]
Re: Advice wanted- Building a 350 SBC for a G30
shaggy #793149 July 18th 2022 5:29 pm
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shaggy Offline OP
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Cheers very informative video. Seems that 882s are the way to go for my build alright.
Propane runs dry and can cause valve seat recession over time so the induction hardened valve seats will be useful.


79 chevy G30 cobra camper conversion.
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Re: Advice wanted- Building a 350 SBC for a G30
shaggy #793174 July 19th 2022 8:05 am
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Do the 882 Heads have accessory mount holes? I dont believe they do, so you would need to get new brackets for whatever you have mounted on there now (Alt).

Re: Advice wanted- Building a 350 SBC for a G30
NEmery #793177 July 19th 2022 9:26 am
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Originally Posted by NEmery
Do the 882 Heads have accessory mount holes? I dont believe they do, so you would need to get new brackets for whatever you have mounted on there now (Alt).

I think the set I have has them, but I'm not 100% on that. I'll check later this week.


[Linked Image from live.staticflickr.com]
Re: Advice wanted- Building a 350 SBC for a G30
shaggy #793178 July 19th 2022 1:03 pm
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shaggy Offline OP
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I'll double check but I'm pretty sure the set I have do have accessory holes.

The early ones didn't but my engine being a '79 I think was towards the end of production of 882 heads.


79 chevy G30 cobra camper conversion.
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Re: Advice wanted- Building a 350 SBC for a G30
shaggy #793582 July 30th 2022 11:12 am
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882s are about the single worst casting to run on a small block save for the more crack prone 624s. If they have the correct accessory holes for your belt drive setup the 462s are worlds better in both longevity and performance. On propane you want all the compression you can get and an 882 head even with a flat top piston will be in the 9:1 range at most. Propane can run more like 12-13:1 compression. A set of 601 heads from a 305 would work well on propane.


1983 G20 Conversion Van, 350 TPI, Reed Hydraulic Roller cam, Ported 906 Vortec, Edelbrock 3817 TPI-Vortec Base, Doug Thorley Tri-Ys, Dual 2 1/2" exhaust, Speed Density 7730 ECM tuned by ME, 700r4 by ME, Stock 1,600 rpm converter, Rebuilt Stock 10 bolt with posi by ME, 3.08 gears, 358 RWHP @ 5,200, 384 RWTQ @ 3,400, 14.66 @ 95.43 w 2.28s 60'
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