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seen in a post by Ryan,J ,that He found the Indy small block heads liked lots of timing(38-42deg,s) something like that. Wondering if anyone has tried this on the track with any results.
Jim.



My old hand ported -1's made best power at around 33-34 degrees of timing. My CNC -1's seem to like 38-40*. Im guessing because they have a much larger chamber. Usually a more efficient chamber requires less timing so Im not sure why they like so much timing either but that seems to be the case with my heads also. My chambers are still 67cc's after being milled .030 and my old chambers were 57cc's.



It's more to do with the shape of chamber than raw size...Those CNC chambers generally wet flow & burn alot differently than a hand ported version of the cast ICH chamber. ie. most hand port jobs do not change the shape of the chamber as drastically as the CNC version is, so end up with 2 completely different shapes. It's a very efficient chamber, I've gotten to see burn patterns off of a bunch of used ICH CNC chambers & they always exhibit a nice burn, it's big part of why they make so much power.