SC or 996 camshaft

scottanf · 09-26-2007, 08:00 AM

I'm ready to start putting my 1978 3.0 back together and have decided to use 95mm 9.5 compression JE pistons (the mahle cyl are in good shape but not the pistons) . The top end of this motor was rebuilt 5k ago and the cams were reground to SC spec. Can I run the JE's without changing to 996 cams and what am I giving up in HP gain.

Kevinwilliams · Kevinwilliams's Garage

Quote:

Originally Posted by scottanf

I'm ready to start putting my 1978 3.0 back together and have decided to use 95mm 9.5 compression JE pistons (the mahle cyl are in good shape but not the pistons) . The top end of this motor was rebuilt 5k ago and the cams were reground to SC spec. Can I run the JE's without changing to 996 cams and what am I giving up in HP gain.

I Had an SC with what was called an "SC" grind and like the performance. I currently have one with a 996 profile. It seems ro me that unless you have a lot of modifications this is over cam-ming the engine. In other words, making it more lumpy than it may need to be. It depends on what you want from the car.

Steve@Rennsport · 09-26-2007, 09:43 AM

Hi:

I do not think you can run the 996 cams (or its profle) in a CIS air-cooled engine.

We either time the SC cams to 3.0 Carrera specs, or use a 964 cam in these CIS engines with excellent results.

dcriss · 09-26-2007, 09:50 AM

Ya, I'm in the middle of a 1980 3.0L SC rebuild and have been investigating similar thoughts. However, from what I have found out (and is shown in Wayne's book as one of his engine picks) this seems to be a decent upgrade:

3.0SC Case (of course)
3.0L (70.4mm) Crank
Either keep the CIS Piston or perhaps use 95mm JE’s.
Cams reground to 964 specs.
CIS fuel system (thus the 964 cam would not be too radical).
SSI heat exchangers.

Not sure on the 996 cam that you mentioned.

More input on this build is found at: Rebuild suggestions needed

Good Luck

scottanf · 09-26-2007, 03:13 PM

Thanks Guys and it was a 964 cam I was thinking about not a 996. Steve I think I'm going to keep the SC cam in. From your reply I understand it should be timed to a 1976-77 Carrera specs not the stock SC?