petee_4204

i have a 305/350 not sure yet the car was sold to me "with 350" but we all know the deal there. However whichever it is i have non center bolt heads on the motor and i have a set of 89 350 center bolt heads and a set of 89 305 center bolt heads lwill these bolt onto this engine i have in my car? Which are more ideal for horsepower?

Damon

They will bolt to the block, yes. Centerbolt heads have a different intake bolt pattern than earilier perimeter bolt heads. Also, centerbolt heads use self-aligning rocker arms where perimeter bolt heads use standard rocker arms. Other than those 2 little "gotchas" they will interchange.

No idea how much power they might be worth over the current heads since we know nothing about the current heads.

brandoz28

iTrader: (1)

my 081 heads that are center bolt have standard rockers. won't know which setup is better for you until we know the casting numbers off of the heads that are on it and the numbers for the 305 heads

petee_4204

thanks for the info. which are generally a better performance head the 305 or the 350 in theory doesnt the 305 head have a smaller cc giving more compression but doesnt the 350 heads have bigger valves so whats the more optimal install?

brandoz28

iTrader: (1)

If they're smog 350 heads they're junk, the 305 ones can be excellent heads on a budget, just have them fitted with bigger valves if you're nervous about it, and port them if you are feeling ambitious. the smaller combustion chamber will raise compression too. whats the rest of the setup?

petee_4204

the 350 heads came off an 89 suburban im almost positive the truck had smog emissions on it with a tbi the 305 heads came off a 350 that was in a z28 iroc tpi i have a 1985 firebird the guy said it had a 350 but it looks like nothing has ever changed including the smog so i think it has 305 since that year didnt produce firebirds with 350's my 85 has a 4bbl carb on it. Thanks for your input what would you do? i am on a budget the car runs fin now im about to put a performer intake on it. The intake is for centerbolt heads i was trying to get away with drilling out the holes to fit my perimeter heads.

petee_4204

cast number is 1801017

petee_4204

will i need new pushrods or can i just reuse the ones thatare in my car

Damon

Any heads that came off a TBI motor (305 or 350) are going to be the infamous "swirl port" heads. Probably not a great performance choice, but maybe still better than an old set of factory 1970s-vintage smog heads.

You will not need new pushrods.

Can't find the casting number you listed.