Hello, I'm wondering if any one knows of what power gains if I put aluminum L98 heads (2.20 1.60 their 53cc chamber to raise the compresion to 10:1 on the L98)on a 305 TPI. I have a 1991 trans am 305 TPI 5 speed . I got super chip,k&n,dual cat to 3 inch pipe to a 3 inch in and dual 3 inch out flowmaster plus some other goodies.

 

Not as much as you'd like. The small bore of the 305 will shroud the big valves, giving only minimal gains. I thought they were 58cc, which is what a stock 305 has.
I'd get some undercut swirl-polished 1.94/1.5's and a proper "3-Angle" valve job, a bowl-port job, and a cam that'll squeeze the most air you can through the valves.

 

I didn't think it would I'll just put the nos on the trans am,and put the heads on 89 IROCZ which has the L98.

 

Thats what I would do.

 

Do a search for "corvette heads" or "aluminum heads" on this forum. I have those heads and have posted numerous times about the problems you will run into with them.
First, they're 58cc's, same as your 305 heads. And their valves are 1.94/1.50, same as a stock 350.

 

I dont think a 2.02 valve will fit on a 305 anyway. Has a little valve to bore issue.