I am building a L48 350 that presently has the cast iron 76cc heads. Factory compression ratio was 8.5. I have been looking at cast iron 64cc heads, but have seen a few sets of 113 vette heads. I know they will raise the compression ratio over the 64s but by how much? I also know that the aluminum heads will tollerate higher comp ratios than cast iron will.

Does anyone have experience running these heads on an older L48 type block, if so how will will they work? This motor will not be a race motor, but it will see only occasional weekend street/strip use. Running premium plus octane booster would be acceptable, if necessary.

 

The L48 CR was actually more like 8.2:1, by the time you take deck clearance into account. If it's been rebuilt, then the pistons are probably at the stock .025" PLUS an additional .020" "down in the hole" at TDC, so the CR is probably closer to 8.0:1 now, with the 882s on it.

With the 113s, the CR will be around 9.1:1 if it's been rebuilt, or possibly 9.3:1 if the pistons are still the stock ones. Not too bad at all.Regular gas is all it will need.

Should work out OK, as long as you don't try to over-cam it. Stick with 210-220° sort of cams.