PCar SBA

I am contemplating to upgrade my cams a little bit "while I am in there". I have the engine apart and am doing a top end rebuilt (heads, cylinders, head gaskets, rod bearings, ARP rod bolts). I also need to have at least one cam repaired (exessive wear on a couple of lobes)

The engine is a stock 91 964 with 993 heat exchangers and a chip feeding into a 915 transmission with 7/31 R/P in a 74 Targa. Yeah baby!!

I was wondering what cam profile you guys would recomend for the stock fuel injection. I don't want to go too crazy or end up having problems with valve to piston clearance. I am using the car for track events once in a while but mostly as daily driver. So it needs to be streetable. I would prefer a profile that can be done by regrinding as opposed to welding up the cams.

I am thinking of going to send the cams to Elgin tomorrow.

Thanks,
Ingo

Steve Weiner-Rennsport Systems

Ingo:

I'll assume that smog compliance is part of the equation here,....

We use the Factory 3.8 RS grind in cases like these.

You can buy new cams or have yours reground as long as the bearing journals are perfect. A good regrind involves welding up and regrinding the new profile, NOT simply grinding and thusly reducing the base circle.

Hope this helps,

PorschePhD

Consider the 993 Sport grind. I can provide the specs if you would like. If offers good street response with a little more low end response.

PCar SBA

I went with Elgin's Super C2 profile. From what I was told it is one step up from the stock profile and a little more agressive compared to the 993 SS. It was done by regrinding my existing cams with some lobe damage.

So far I am very happy with my choice. I noticed that the idle is a little bit more unstable. Before, I was not able to stall the warm engine (with it's light conversion flywheel) under any condition. Now I have to make sure to not disengage the clutch before I am down to 2000 RPM.

The car makes plenty of power and it is hard to tell how much the new cams added to the equation and how much the rebuild itself helpled. I have not yet used the modified chip since I want to break in the engine first. It has a different idle code that acounts for the light flywheel.

Ingo

Alan C.

Steve,
Any issues with piston clearance on the 3.8?

Steve Weiner-Rennsport Systems

Hi Alan:

Are you speaking of piston-to-valve issues?

In certain cases, yes. The larger RS intake valves require that the pistons are machined for clearance.

Alan C.

That was the question.
Thanks Steve

Bill Verburg

I used the Webcam RS hyd cam w/ my 993 RSR pistons. There were no interference issues. These are the non slip fit versions/coated skirts/tapered wrist pin