Are 1st gen 986 heads a direct interchange with the 996 heads? (I know that there is a difference in the combustion chamber size...at least I think I know that.) I have a chance to pickup a pair for a good price for spares. The part number on one of the one's I'm looking at is 99610467110R. I seem to remember hearing that some of the bolt holes aren't in the same place.

 

2000-2002 3.2L heads are the same as 3.4L heads. 3.4L heads have 3cc bigger combustion chambers.
986 heads from smaller engines have smaller valves making them useless to me.

 

Just so I'm clear what I'm asking about...I have a 1999 996 Cab with a 3.4L and the heads are a set of 2.7L 986 heads (year?).

 

Does anyone know if these are a bolt-on interchange?

 

You will have to drill & tap holes to bolt on the intake manifold & exhaust heat shields. The valves will be smaller & the cumbuston chambers will be smaller raising the compression enough to require 100 octane fuel.

 

Thank you! That tells me what I need to know. I think I'll pass on these. The valve size and combustion chamber size are easy remedies to solve, but by the time I have all the machine work done, I'd be better off paying more for the correct heads.