Nice setup you have

So in case of CHI, I need to reckon with what pistons to use too - something more to thinker about...
quote:Originally posted by Kid:
... I wonder whether compared to the CHI's, they would be really worth the extra money...
quote:
I just finished a back to back dyno test for a customer; swapped my SCM alloy heads in place of iron 4V heads.
His motor is a 351C +0.030", stock un-ported 4v closed chamber heads, 61cc chambers, 10.1:1 compression, Crane f238 solid cam, 36° total ignition timing, my dual plane manifold with a BG 775 carb, full exhaust system, 1-3/4" tri-Y headers, 2-1/4" mid pipe & muffler, 2" tail pipes!!! Very very basic engine! Built 20+ years ago! The motor baselined at 397hp and 401ft/lb. It peaked around 6000rpm.
We installed my new SCM 4v's, compression was bumped up to 10.3:1 due to the slightly smaller chambers, we adjusted ignition timing to 29° total; no other changes. The dyno numbers improved - 468hp 435ft/lb. Horsepower peaked at 6400 with my heads . But the peak Hp stayed fairly flat from 5900 to 6400!
-Scott