Mild 350 sbc build, what do you think?

[mjrwraith]

Ok so I have just acquired a 1972 GMC C15 long bed fleetside. I want to do just a simple restore job with a focus more on comfort than a fancy paint job or hot rod motor. I do however want to add a little extra power and a few more mpg out of it. So after some research I wanted to throw my idea on how to set this up out there and get some of your opinions. So here it is, I'm going to take the stock motor with all the lower end being factory spec, and put a COMPCams 252he cam with the new valve train and all to match. Then take the stock intake manifold off and put on an edelbrock rpm intake with the stock quadrajet. Leave the stock exhaust manifolds on and put a b&m shift kit in the TH350 tranny. I'm only looking to get around 25 more horse and maybe 2-3 mpg more out of it. Compression will be stock, which I believe is 9.5:1 may be wrong I'll have to double check. I think that covers everything so any tips or advice would be helpful thanks.

[DonnieB]

I would consider exhaust too.

[adricar1]

personally with that cam i would go with a performer manifold over the rpm, as that cam will not the rpm up top.Exhaust would as mentioned be a consideration as well. have you looked at there 260 cams ? pull well and a little more rpm.

[mjrwraith]

Yeah I am looking at exhaust just forgot to to add it to the list. I'm looking at going with true dials. After looking back over my parts list and the edelbrock site I'm definitely going with the performer. I had one on one of my old grandwagoneers and loved it. I want the rpm range of the 252 I compared the two and the 252 is in the rpm range I'm wanting.

[hugger6933]

I would consider the 260h. I have used the 268H in many cases and it has never let me down. Even going with one that far from the stock spec it helped the motor run so much better in all cases it got better gas mileage. and power boy howdy!!the expectations you have are fine if not just a little low but being low is ok so your not disappointed if it doesn't do great, but it will. Jim

[mjrwraith]

Originally Posted by hugger6933

I would consider the 260h. I have used the 268H in many cases and it has never let me down. Even going with one that far from the stock spec it helped the motor run so much better in all cases it got better gas mileage. and power boy howdy!!the expectations you have are fine if not just a little low but being low is ok so your not disappointed if it doesn't do great, but it will. Jim

My reasoning for the low duration and all is along the fact of the last motor I built, which was an AMC 360 in a Grand Wagoneer, I put the 270H cam in it and it was too much. The motor got horrible mileage I had to put a 750 CFM carb on it just to keep the poor thing from falling on its face.

[mechanicalman]

Originally Posted by mjrwraith

Ok so I have just acquired a 1972 GMC C15 long bed fleetside. I want to do just a simple restore job with a focus more on comfort than a fancy paint job or hot rod motor. I do however want to add a little extra power and a few more mpg out of it. So after some research I wanted to throw my idea on how to set this up out there and get some of your opinions. So here it is, I'm going to take the stock motor with all the lower end being factory spec, and put a COMPCams 252he cam with the new valve train and all to match. Then take the stock intake manifold off and put on an edelbrock rpm intake with the stock quadrajet. Leave the stock exhaust manifolds on and put a b&m shift kit in the TH350 tranny. I'm only looking to get around 25 more horse and maybe 2-3 mpg more out of it. Compression will be stock, which I believe is 9.5:1 may be wrong I'll have to double check. I think that covers everything so any tips or advice would be helpful thanks.

Stock compression ratio that year stock was advertised at 8.5 but if you checked the head chamber size and with the stock head gasket it was closer to 8.0 than 8.5.

Regardless of head use the fel pro steel shim 1904 gaskets to enable quench in the combustion chambers.

Those dish piston engines with that size cam just love smaller combustion chambers like the double humps.

For $399.00 you can get these rebuilt 65cc heads, they are likely rebuild 305 castings they have new bronze wall valve guides, stainless valves 1.94"/1.5" valves with new springs that will more than handle your cam.
http://www.aeroheadracing.com/chevy.html

Do you have dual exhaust? I think that engine would like dual exhaust with a crossover pipe. Stock single Y pipe is very restrictive with bad reversion.

Ensure a good distributor on it around 24' mechanical timing at around 2500 RPM (more or less depending on heads and cruise RPM best to have all in at highway cruise for mileage) with about 18' adjustable vacuum advance hooked up to ported. If it pings then set it back as nec.

This should get out of it all it has if the carb is set up right. If it's the original quadrajet with the divorced choke, a new aftermarket manifold will cause problems with that. Edelbrock 7104 Performer RPM quadrajet manifold.
http://www.summitracing.com/parts/EDL-7104
It offers a special choke rod to accommodate the divorced choke, Edelbrock #9172.
http://www.summitracing.com/parts/ed...GoWxoCixnw_wcB

If Vortec heads interest you, let me know I'll tell you what you need.

[slikside]

subd.

[Warrens69GMC]

If I were to do that to my truck I would go with Xe256/vortec heads/ performer manifold

[67 chevelle]

Originally Posted by Warrens69GMC

If I were to do that to my truck I would go with Xe256/vortec heads/ performer manifold

I think this is great advise , vortec heads are some of the best for all around performance and gas mileage .

performer manifold fits your desires , rpm is more a street strip manifold for higher """rpm"""