# Engine builders for 67 GTO 400



## bowsher21 (Dec 8, 2011)

Any engine builders with building advice for my stock 1967 GTO with 400ci single carb? 

Motor will be torn down for inspection and to touch up valve job and seals. I thought while I was in there I would make some changes if required. I want it to run on 93 pump gas. What do I need to do to avoid knock and to retain the stock power level that it has?


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## geeteeohguy (Feb 2, 2008)

Lots of information has been posted on this topic. You will need to run custom pistons (dished) for a lower CR...about 9:1. Or, you can try to find some 80-90cc heads. I would install a dished piston and use the stock 670 heads. I would also probably go with a Comp Cams XE 262 or 268 cam. I retrofitted my '67 GTO with a pair of 1970 455 heads that are 87cc, and it runs on 89 octane. Hard to find the heads, though, and $$$$. It's amazing how strong these 400's are at 9:1 with the right cam. Keep the stock intake and carb...pretty hard to beat. Also, there is a pro builder on this site who posts every now and then...Mr P Body. Dig thru his old posts and you'll get a ton of great info.


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## bowsher21 (Dec 8, 2011)

I have some background with 429/460 BBF's and I have seen detailed builds with O.E.M. heads @11:1 cr that produced over 700hp, using single carb on 93 pump gas. It is very common to see this. All have flat or slightly dished pistons to promote better flame travel. I understand flame travel and quench have alot to do with success of running on pump gas.
I would hope to find some skilled Pontiac engine builders that have experience with pump gas performance builds on this site for more input.
Your on the right track with the cam & custom pistons but I will be using the #'s matching/orignal heads.
Thanks for the reply, I will be looking for Mr.P


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## bowsher21 (Dec 8, 2011)

*Pump gas build*

Any one have examples of a performance build on a 400 but still using pump gas?
What bore/stroke, pistons, cam specs, valve sizes, port work did you do? 

I would like to use my current matching OEM parts but willing to change pistons, bore size, valves, cam and do some mild port work.


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