Question regarding 2.7 CIS Systems

[blau911]

Guys,
I have a 74 911 with original 2.7 motor that the PO changed over from CIS to carb's. I was thinking of changing back. I am wondering if all the 2.7 CIS set-ups for 74-77 are the same and can all be applied to a 74 911 (non S) motor. Can I for instance use a 1976 2.7S CIS set-up on a 74 2.7 non S motor? If not, is the reason because the head diameters are larger on the 2.7S motors? What is the actual difference between a 2.7S 165hp and non S 2.7 (i.e. 150hp) motor? Compression, cams, valve sizes, or injection?
Any info appreciated.

[Targalid]

The 2.7 from 74 is considered a desirable setup. What you may not already know is whether the previous owner changed cams and pistons. If so, changing back to CIS may require changing back to the original cams and pistons also. If that is the case, it may be quite expensive to change and you would be better sticking with the carb setup you have now. The real experts on this forum can tell you how to find out. I can tell you already that they will insist on photos, lots of photos.

[Joe Bob]

Almost 40 year old parts. I would look at the Bitz, Megasquirt EFI. You probably spend the same and get new parts. There was a thread recently about it.

Click on the link.

PROs vs CONs of webers over cis?

Maybe you can make a trade or sell your carbs....never know.