964 Cam question.

[Lee]

I've got a 1978 SC Targa that has been down for a year, due to having broken two head studs, and suffering a bent valve. I want to rebuild over the winter, and I'm starting to gather up parts. I want to increase hp, and have bought a set of 964 cams off of e-bay. In addition, I want to put on ssi heat exchangers, a two in-two out muffler, and higher compression pistons. I'm going to keep the CIS for now. My question is this, can I use 3.2 pistons with a higher compression ratio with the 954 cams?

Also, since my car has been sitting still for a year, what other preparations will I need to take, in order to get road-ready.

Thanks.

[Superman]

Of course, with the same cylinders you cannot use wider pistons. Are you thinking about using pistons out of a Carrera 3.2?

I do not believe that higher compression pistons will be a problem, either for your CIS system or 964 cams, or both. I expect they will work together just fine. In fact, according to legend, you are heading toward a pretty sweet set-up. (Early SC heads and intake system, high compression pistons, equal-length exhaust and more effective cams). I think you will be pleased. No, I know you will be pleased.

[Lothar]

Lee,

Check out the attached thread from this week. I think this might answer your question about the 964 cams with SSIs and higher CR. Of course, if you go with the 3.2 p's and c's, I will have to pummel you for having more ponies than me. Besides, SC's are supposed to be 3.0 L!

What do I have?

[Lothar]

What kind of hp and torque would the above engine develop with the 3.2L pistons and cylinders?

[ChrisBennet]

Lee,
Your 964 cams, are they from a real 964 or are they SC cams with a 964 grind? Most people just get their cams reground. (I paid $300 a few years ago for mine.) With real 964 cams you need to do some machine work to chop off the end of one of the cams. Real 964 cams use different parts to hold the cam sprocket so you need to get some different parts if you didn't get them with the cam.

3.0 and 3.2L both have a 95mm bore but the pistons have different wrist pins diameters so no, you can't use the 3.2 pistons with your SC. Sorry.

-Chris

[Lee]

I appreciate the replies...

I'm not certain what horsepower I should be aiming for. I assume with modest upgrades like this, I can count on 200 - 210. I imagine that, having only driven it when it needed a top-end rebuild, these additions won't seem so modest.

I bought the cam on e-bay, from a guy who said he took it out of a C2, so it is a real 964 cam, as far as I know. I thought about having my cam reground, but I have nearly 200,000 miles on the car, and since his cam has 30,000 on it, it seemed like the thing to do. I'll make certain to find someone knowledgeable to make the right modifications to it.

As far as understanding a displacement increase, I'm in a bit over my head. Would going to 3.2 pistons require a different crankshaft? New cylinders also? These are things I need to look into. I'd like to keep the cost down, if I could, and have been looking into JE pistons.

In truth, I could be quite happy with keeping it at a 3.0, making a few simple and reliable improvements, lighten the car (and myself) a bit, and just having a ****load of fun driving it .

[Lothar]

Lee,

When you mentioned 3.2 pistons, I thought you were talking about 98mm bore and new cylinders. That would result in a 3.2 SS or short stroke engine that I hear is very nice. However, if you need new p's and c's, so much for keeping the cost down.

I have Euro 10.5:1 pistons in my car. They work with CIS just fine and you can still use your 964 cams with some modification as Chris explained.

I suggest that you look at the thread with details about my car (see previous reply). The consensus was 210 to 220 hp, not bad for starting life with 180 hp. If 100 lbs of weight reduction are equivalent to 10hp, then my performance should improve as if I had an additional 20 - 25 hp. I put some weight back in the car in the form of a roll cage, but I'll sleep better at night for it.