2.7 heads on 2.4 cylinders?

[turbo dave]

Will they fit (is the OD of a 2.7 cylinder the same as the OD of a 2.4?) Obviously the ID is different, but I understand that the Alusil/Nicosil cylinders are thinner wall. Can I use my 2.7 heads on cast iron 2.4 cylinders (cast iron)?

Thanks,
David

[john walker's workshop]

the bevel around the hemi combustion chamber on a 2.7 head would keep the head from contacting and sealing to the 2.4 cylinder surface, inboard of the head gasket o ring. a 2.4 head on a 2.7 works fine though, and raises the compression slightly because it's not beveled for the larger cylinder. same basic head, but one's beveled.

[turbo dave]

Thanks, John, thought it was a long shot.

[911SCfanatic]

On the flip side, I want to use my 73.5T 2.4 heads on a 2.7 cylinders. What additional machining, if anything, needs to be done to make this work? Looks like porting the heads to S-spec will cost ~$650 through EBS--cheaper than getting S-heads. Also, about how much additional compression do I get? I was planning on going with the 9.5:1 JEs already.

[john walker's workshop]

2.4 heads on a 2.7 are a bolt-on. and they raise the compression a tad. (as long as you don't have a wierd piston crown that would contact the unbeveled edge of the combustion chamber). they work fine with CIS pistons and euro 2.7 (MFI) pistons.

[911SCfanatic]

JW, any experience with high compression JE's? Should I have the combustion chamber beveled, if that's possible, as a precaution? And I suppose if I have the decks machined then I'll have to be even more cautious.

[john walker's workshop]

might as well use 2.7 heads if you need to bevel them. same head other than the bevel. hard to say if the J&Es will clear. if there's a flat area around the crown, maybe, but if the curve of the crown goes all the way to the edge, then probably not. a test assembly with clay should tell you.