964 camshaft upgrade question

[belauto39]

Hi,

I,m presently doing a top end job on my 964.
As I'm there, I'd like to make a slight camshaft improvement.
My car is a daily driver with cat and primary by-pass, chip, K&N and 1989 clutch (no DMF and not too light).

Any opinion would be appreciated.
Here's some specs:
Model Valve Duration Valve lift
0,040 0,050


stock I 246 238 0,470
E 232 226 0,430

option1 I 246 238 0,485
E 232 226 0,450

option2 I 248 242 0,475
E 236 230 0,455

Thanks for help.

[Bill Verburg]

Option 2 looks like a minor revamp of the older 964ss cams, which work very well in a street 964 w/ stock intake

I've got to wonder why you want to do this on a daily driver as it does affect low speed torque characteristics. It would work better on a lightened track car.

it's certainly doable and could also benefit from some header type exhaust in lieu of the stock plumbing.

[belauto39]

Thanks Mr verburg.
In fact, the main reason is I've never liked stock things.

I thought option 1 was better: higher lift but no change in duration so no real change at low rpm. Am I right?

[Bill Verburg]

I really have no basis for comparison

I have experience w/ 964ss and 993RS cams used on a 3.6. They add a little more punch at the top at the expense of a little down low. They work best w/ tighter gearing and a more efficient exhaust.

[kurquhart]

Originally Posted by Bill Verburg

I really have no basis for comparison

I have experience w/ 964ss and 993RS cams used on a 3.6. They add a little more punch at the top at the expense of a little down low. They work best w/ tighter gearing and a more efficient exhaust.

Will 993 RS cams fit a 964 motor?

[Bill Verburg]

Originally Posted by kurquhart

Will 993 RS cams fit a 964 motor?

Not the oems, they would need to have a keyway machined into their noses

The SS(993 105 246 70/993 105 247 70) are a tad more agressive and is designed for mechanical lifters, that's the one to use. The part #s I gave are the factory SS/Cup cams Dougherty, WebCam etc all have equivalents

Ninemeisters been able to use much more aggressive cams but w/ a Motec conversion.

[kurquhart]

Originally Posted by Bill Verburg

Not the oems, they would need to have a keyway machined into their noses

The SS(993 105 246 70/993 105 247 70) are a tad more agressive and is designed for mechanical lifters, that's the one to use. The part #s I gave are the factory SS/Cup cams Dougherty, WebCam etc all have equivalents

Ninemeisters been able to use much more aggressive cams but w/ a Motec conversion.

Thanks, Bill. That's what I was suspecting based on some of your other posts. I am guessing that they would also be missing the P/S gearing (but this can be retrofitted).

But now I am confused as to what I actually have my hands on. The 964 cams in PET start with 930. The 993 cams seem to all start with 993. The cams in question are stamped "964 246" and "964 247". Are these really 993RS cams?

[Bill Verburg]

Originally Posted by kurquhart

Thanks, Bill. That's what I was suspecting based on some of your other posts. I am guessing that they would also be missing the P/S gearing (but this can be retrofitted).

But now I am confused as to what I actually have my hands on. The 964 cams in PET start with 930. The 993 cams seem to all start with 993. The cams in question are stamped "964 246" and "964 247". Are these really 993RS cams?

Not likely, oem 993RS cams will not be keyed and will have the pump notch and an oil groove for the hyd lifters and will have 993.xxx.246(247).xx

246/247 is generic id for R/L cams

there was no 964RS cam

the SS were used on Cup cars

there is also the GT2 Evo cam which is very similar to the SS

You'll have to put it on a cam doctor to find out what you have.

[kurquhart]

Mystery solved: in my ignorance I was looking at the cast number for the blank:


The actual part number is stamped in the end:


So while these are OEM 993 RS cams, they are not the best match for my engine. Anyone have a set of SS for sale/trade?