2.7 Rebuild Guidance-identification, confirmation, recommendation.

[Sway Bar]

Need a little guidance from some of you more experienced individuals. I’ve done a few motor rebuilds but mostly vanilla 2.4’s and 3.0L’s except for my 3.0MFI that I did.

Anyway, I’ve never done a 2.7CIS and a I’m doing one for a buddy that has thrown me a curve ball. This motor has no history except that it was built by one of those ‘ole skool’ Porsche guys many years ago (maybe a dozen years). It ran great, absolutely no leaks but my buddy cooked a cylinder and it now requires a replacement. Easy? Well…

So, one can see the nicely cooked cylinder. The piston looks no worse for wear so I was thinking just replace with new Jug and be done. (after spec’ing everything of course).




1) However, when I run the numbers and look at this cylinder it’s a KS Alusil but if you look inside and stick a magnet on it it’s Nikasil…so, somewhere way down the line it may have been re-plated or is there something else I'm missing??
2) Then I look at the piston and run it’s number, look at the chrome oil ring, and do magnet check this comes up as Alusil as well?? 8.0-1 I believe.






So, am I correct in my identification and is this an example of the cardinal sin of NOT putting Alusil Piston and rings in Nikasil? All the cylinders look great and I can’t see any vertical wear or scaring. Is this an old wives tale, not enough mileage over 10+ years or could I be wrong in my identification?


Now for your guidance part, obviously we need a replacement jug…almost easy. But rather than just replacing the 1 jug and buttoning it up with the current Alusil pistons and undo what I’ve seen. We’ve sourced 6 Mahle Nikasil cylinders so thinking grab some JE 9.5 -1 pistons and rings to make it worth while. And if so do I need to change cams to make it worth while when retaining the CIS? Or does one have another suggestion?

Which brings me to another ‘issue’. I measured the cam timing prior to removal (the cams have stock numbers and I can’t ascertain if they have been reprofiled-I have never seen a reprofiled cam off hand and besides re-stamping I don't know if it's easy to tell) but they were timed at almost 3X the spec. I think off hand 76CIS cams are somewhere around .46mm but the left was at 1.3mm and the right at 1.5mm. If these are in fact stock what does advancing them this far do?

So really, the ultimate end question is can I keep a stock came with 9.5-1 JE's for the CIS or do I go in for a penny in for a pound and get another 3 bearing cam? If so what? Any other suggestions, ideas?

I know a lot of questions but I can’t learn anything unless I ask.

Thanks in advance.