Howdy all!

Finally making some progress on my engine for the '67. Hoping for some feedback on my build if you have the time, want to make sure I do it right! Planning on using as a Sunday driver but may also end up classic car auto-crossing it. In talking with Keith Black and Edelbrock the engine should be right around 10.1:1 CR on pump gas. Please let me know if you need any more details, tried to be complete. Thanks much for your time.

Block: 400 bored out 030 and decked
Crank machined and balanced (with pressure plate, harmonic dampener)
Pistons: ICON Forged Pistons - IC9946KTM030
Heads: Edelbrock 61595 (roller rockers)
Cam: Comp SP 276/282, 224/230, .503/.510, 112LS
Intake: Edelbrock 7156 Performer RPM Intake
Fuel: Deciding between Either Carb or Throttle Body Injection

Most of the parts look OK to me.

BUT,

If you have not already bought 'em, don't buy those pistons ! Those are just a forged version of the 8-eyebrow cast rebuilder pistons. Their purpose was so you can run the earlier heads, that have a different valve angle. You can also bore a 389 .058 over & run the 4.120 bore version.

https://butlerperformance.com/i-24453315-icon-fhr-forged-flat-top-pistons-3-75-str-400-std-bore-389-058-over-bore.html?ref=category:1234832

I'd go with a good flat top, with only 2 valve reliefs. My preference is the Auto Tec brand. You can get any pin height you want, so that you can get near zero deck height, without cutting any more off the block. Another advantage is that they have thinner rings, which most recommend.

I'd rather have the Speed Pro forged flat tops than those Icons.

But, if you already have 'em, or have decided on 'em, so be it. Whatever pistons you use, you need to try to get up to zero, or near zero deck height.

I recommend a good, properly rebuilt Q-jet. When built & tuned correctly, they're hard to beat, especially if you'll be doing a lot of street driving. I'm strictly old school. So, I'd never put fuel injection on a Pontiac engine.

But, as I've read on most all Pontiac forums, "It's your car & your money, so build it like you want it."

I plugged in some numbers, to calculate your CR. 400 + .030, 72cc heads, 10.8cc valve reliefs, Fel Pro 1016 .039 x 4.3 head gaskets, .000 deck height. CR = 10.03

http://www.wallaceracing.com/cr_test2.php

And if you don't have zero deck height, the CR will be lower. Also, if you use thicker head gaskets, your CR will be even lower. Alum head engines can run OK on pump gas, with at least 10.5 or a little more CR.

Just changing to SP L2262F030 pistons would raise your CR to 10.45. And the 2-relief pistons would put it up just a hair more. Not saying it won't run good with less CR. But, more CR will make a little more power, if that makes any difference to you. But hey, with only 10:1 CR or less, you might be able to get by with 87 octane pump gas. That'll save you a few bucks, if you do much street driving.

You didn't mention what rods you have, or plan to buy. I'd go with forged H-beams. The RPM brand are $400. Best price I can find for Eagle brand H-beams, right now, is $459 shipped.

http://www.racingpartsmaximum.com/sae4340steelhbeam-2.html

https://sportcompactwarehouse.com/e...&ymm_gid=1&gsID=pwf736954g1&

Thanks for the reply oldskool! I have already bought, assembled and balanced the pistons so changing them out isn't a likely option. Thanks for the opinion on the Q-jet. I am not hard decided on either at the moment, its a total resto-mod so having some modern stuff on the vehicle doesn't concern me but like the way carbs work as well!

Sounds like I am still in good shape as far as overall engine build. Cam specs look pretty good? I read about the lobe separations and how they effect things. I think 112 is a good compromise and will provide plenty of vacuum for my power brakes.

Engine building is all new to me and have really been enjoying learning about things. Really appreciate folks taking the time to teach me about stuff.

"...Thanks for the opinion on the Q-jet. I am not hard decided on either at the moment..."


I see you're in WA. SMI is in CA. Might be the closest well respected Q-jet builders on the West Coast.

https://www.smicarburetor.com/products/sfID1/28/sfID2/9/sfID3/100

Quadrajet Power is down here in the South part of Texas. Don't know that shipping would be much higher. I recently bought some rebuild parts from them & got free shipping.

https://quadrajetpower.com/

I agree with oldskool, original design works fine. I did a couple engines within the last 3 years. I got my stuff from Butler and they were helpful in helping with my engine design. Have a look at my Engine Test Stand. Great way to break in your engine and test before you put it in the car.