I got a 305 tbi, can vortec heads from a 305 or 350 fit on my 92 firebird??

 

Yes, both will physically bolt on, but the 350 heads will have a larger combustion chamber and therefore LOWER your compression ratio.
You will LOSE power.

 

he is correct and the 305tbi is already at something like 8.5.1 compression ratios. that's a dud. vortec heads are a great upgrade but then you have to change the intake manifold as well. a set of stock vortec heads are fairly affordable but by the time you buy a manifold as well you could almost buy a better set of heads made for the 305. 175-180cc heads are good for a 305. the set im looking at have a 56cc combustion chambers that will raise the compression ration closer to 9.5.1. the better heads and increase in compression will be power you can feel.

 

305 TBI cars are at 9:3 or 9:5 compression stock. Big upgrade to go with 305 Vortec heads and a carb Vortec intake can be bought cheap as well as an adapter to use your TBI with it. Still won't be a rocket id be looking for a 350 if I was wanting to make power.

 

Any head part numbers or truck/car years to look for these 305 Vortec heads? A true bolt on with the right manifold?

 

L30 heads are 12558059 I believe.

1996 - 2000? I'm not certain what year production ended.