I am kinda new at this engine rebuilding thing and I would like to know if the heads on a 305 and a 350 are the same? Interchangable? would it produce higher compression? And would it be possible to create a mean 305?(i'd like to keep the stock motor).
Thanks....

 

Stock heads would work fine, the compression ratio all depends on the pison you use, the chamber does make a difference but the piston is the easiest way to change compression. As for creating a mean 305, it is easy as hell....

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1987 Firebird Formula
305 LG-4
GM Vortec heads 2.02x1.6 valves
Crane CompuCam 2030
700-R4 Trans
4 barrel quadrajet
edelbrock performer intake
Hypertech Thermomaster Chip installed in a nonworking computer
Open Element Air Filter
No Cat with flowmaster exhaust
NO MORE COMPUTER CRAP
NON computer HEI Distributer

- Soon to be installed
700R4 Lockup kit
Edelbrock TES
Stall convertor

 

All stock 305 heads since day one are 58cc combustion chambers. All stock cast iron 350 heads are either 64cc or 76cc, which will drop compression considerably. The only 350 head that has 58cc chambers is the aluminum 80s 'Vette head.

If you want better heads for a 305 the only true performance replacement is the S/R Torquer 305 head. Worth 20-30HP over stock they say. Stock bolt on.

Others have milled down the new style Vortec castings from 64cc down to about 60cc and also used them with good results, apparently. They don't have exhaust crossover passages (no EGR compatibility) but they make good power.

With flattop pistons (like used in the L-69 HO 305) and 58cc heads a 305 is going to be around 9.2:1 compression which is fine for street use.

 

I'm pretty sure that the 305's have 58 and 64 cc heads. I will look this up but i do know that the cc's of a head DO have a lot to do with the compression ratio. I have a set of 85 HO head on my car with 58cc chambers but the 89 L03 heads are 64 cc with 1.85 1.50 valves. Just changing the heads take the CR from 9.3 to 10.02

 

moving to the general engine board