Ol' Fart's Firebird Fantasy

[goinbroke2]

Originally Posted by oldskool

Nope, the '72 400 has a 310hp factor. The 455 is only 315. It would be better. But those 455 heads had press-in studs and no end exhaust manifold bolt holes. And I don't have a set anyhow.

A '75 GP with a 455, factored at 300hp looks pretty good. And they show the 5c heads are legal on it. These heads are almost identical to the 6x heads that I have. And they have screw-in studs and all 6 exhaust bolt holes.

But, I just noticed that NHRA does not list any accepted replacement piston for the '75-'76 455's. They must be oddballs of some kind--maybe a bevel around the edge, or no valve reliefs. Anyhow, a barely under car at a divisional will most likely not be torn down to check the pistons. And I assume that if somebody requested it, NHRA would probably allow the same pistons they have listed for '70-'74 455's, since there would be no big performance advantage.

That head doesn't have two ears snapped off?? There are no outer manifold bolts??
Wtf were they thinking? Unless the flange on the header is 1/2" thick or something, how would that not leak?

[oldskool]

Originally Posted by goinbroke2

That head doesn't have two ears snapped off?? There are no outer manifold bolts??
Wtf were they thinking? Unless the flange on the header is 1/2" thick or something, how would that not leak?

Here's a couple of ways they do it.

[Mark Yacavone]

Make it a 71... 66 cast heads.
@325 , not a bad combo
Run it slow for 6 mos. and get some hp off.. Shouldn't be a problem for you.

Right ..Sell the drivetrain, and you'd have a few grand in it, and you'd have a nice looking car to race. ;-)