Would a 642 head be good for my 305 with a carb, LT1 cam and intake manifold swap?

 

No.

And a pair would be twice as bad as just one.

In fact, it's one of the worst possible choices there is.... a 76cc chamber smogger.

Your compression would be unbelievably low. My calculator says 7.7:1.

The motor would make just barely more power than the amount it consumes internally. If you did nothing else to your TBI motor except swap to those heads, they'd probably cost you 40-50 HP off of whatever it makes now.

 

Might make sense if you were going to run the engine on Kerosene. LOL.

There are much better head choices out there for only a few more bucks.

 

Ok, i was thinking that might have been the bad ones. Well, im thinking that i might stick with my stock heads for now, would it be worth it to go ahead and get the ported and polished?

 

i was wondering what kinda of hp and compression i will end up with if i get my heads ported and shaved to the almost their limits.(they are l26's)its a tappet motor with mild cam but will be gettin one with almost .510 and it is a '75 4boltmain bored .060 over with a 750holley Double pumper.Im just want a close estimate????????????????

 

my guess would be 490320495hp and about the same in torque.













seriously dude, i don't think i have ever seen a more vague spec sheet for an engine. what cubic inch, what head, what are the specs for the cam, what intake, what exhaust, what stall for the tranny, what rear gear.

 

origanal 75 350 .060 over l26's, rpm performer or air gap, hedman long tubes into true duals with flowmaster 40's not cats, 2800 stall and 3:42 posi.