From my understand with the info I got from Andy, the heads are a direct bolt on to a 6.1 other than you would need the 6.4 valve covers. There seems to be some small casting differences but nothing that affect bolting them on the 6.1. I believe the chambers are slightly larger and will drop the compression from 10.3 to 10.1 . They will not bolt on a 5.7 because the valves will hit the tops of the bores because the bore is smaller. Andy said the 5.7 bores could be notched to use them but If I understand correctly it's not cost affective.
So Andy, Using these heads on a stock 6.1 bottom end? Will the drop in compression make that big of a difference? I want to do your ported heads, ported intake, cam I need to discuss with you and getting it tuner right. I'm going to run the stock 6.1 manifolds, Corsa cat-back and considering the Solo HF cats. I want to keep it emissions friendly for Texas cause I don't want to deal with all the BS come inspection time.
Ok so if we mill the heads to bring the compression back up on the 6.1, will it cause issues later when I want to put them on the 426 or 440 stroker short block after the first of the year?
I was considering the solo HF cats just for the fact that they seem to be having real good luck with not throwing CEL codes with them. Most of the emissions stations around here don't do much on the visual, if it will pass the OBD test you are good to go usually.
Would I see similar gains on my 6.1 that currently has ported 6.1 heads ( given they are very close to Eagle heads in performance and flow -sans midrange) if I moved to ported Apache heads?