OK... I did do a search, and got some of the things I was looking for, such as solving the chance of overheat problem, and I know that the block itself on the outside is pretty much the same. I am curious as to performance, etc. I will be rebuilding this engine, and I would like some input as to what I should do with it. I really don't have alot of $$$ but I do have some. I work more on the barter system . I would like to get at least 400hp out of this combo. I know there are quite a few of you out there that have played with this combo, and I would really appreciate you input and or any tips you may have. Being that the 400 sbc is already a torq monster, I will be siameseing the intake with full gasket match and port and polish. I am unsure of which block it is yet. the fella is sure it is a 509 block, so I won't know what block or heads it has till I pick it up either tonight or tomarrow. Thanks very much... And sorry for the long post.

 

No one???

 

Use the block, ditch the heads. 400 heads do not flow well. Get yourself some good aftermarket heads. If you cant, then I wouldnt bother building it until you can.

Then build it like you would any other small block, for the rpm range you plan on running in. If you plan on using NOS, then build the bottom end forged.

 

So all 400 heads are junk??? Well with a TPI setup, I can only get around or up to 5000 rpm anyway, and I hear the 400sbc run out at 5500 ususally, so that is where I stand as in RPM. That way I can run a tall tire such as a 295/50/16, I will have tons of torq to get out of the hole, so... I guess I will need to see what block it is..I do know it is a 2 bolt though, which is fine with me. Thanks for you input..

 

Just FYI, as Mike said, 400 heads are junk. Even GM admits that the 76cc 400 heads flow pretty weak. The cast iron 64cc L98 heads flow better. Additionally, around '75, the 400 head castings were redesigned to reduce the weight of the heads (part of the fuel economy stuff after the 74 oil embargo). Once the lighter heads were in use, cracks came up a lot mor often than with the older castings. I lost several heads until finally going with some 350 heads with steam holes drilled.

Also, going to some later model heads will assure you will get all of the accessory mounting holes at the end of the heads. The 64cc heads will also give you a chance to bump your compression a bit depending upon your pistons.