305 heads

[nova68]

can really put 305 heads a 350 and make more power? is this because the values are bigger or what? maybe i am wrong i dont know?

[molhannah]

The 305 heads have a 58cc chamber and 194 valves. They will give you a higher compression ratio, but it might mean a knocking engine with the low octanes we have now days. You would be better off having your heads punched up to 202's and do some minor porting.

[nova68]

i have a set of high performance 305 heads that one of the hot rod guys gave me should i put them on or not?

[molhannah]

Can't hurt and it's not that hard, you won't know if you don't try!

[MrPbody]

There are three basic versions of the 305 head. Some of the previous statements are correct. Some are not. The "large valve" 305s (601, 434) are 1.84" intake valves. Most of the others are 1.72's. There's a 72, 68 and 58 CC chamber, depending on casting number.
We typically "open" the chamber around the intake, to "unshroud" the valve. We also install the 1.94 valves. The 305 has a smaller bore than 350. This is the reason for the 1.84 valve. If enlarged properly, the 305 head is a viable performance unit.
Pay close attention to static compression, as previously stated, as detonation IS a real issue. 9.5:1 is considered the practical limit for 93 octane.