Cam timing question and more

[skimp930]

Hi gang,

Going through a top end rebuild for my 88 930S. My mechanic told me I have 964 cams but timing was set at 1.2 and 1.15mm which is lower then stock specs at 1.26 (i believe). I wanted SC cams for more lower end power but I've read in this forum somewhere that you can change the cam timing for the 964 closer to SC spec and no need to change cams. Is this correct? If so, what timing should I set it at?

Here's my current setup:
3.3 Stock P/C and stock 7/1 compression
GT35R turbo
B&B headers/Fabspeed muffler
Full bay Garrentson intercooler
Rarlyl8 adjustable WUR/ Fuel head modified for more fuel
964 cams
Add 1 bar sping (currently stock)

What cams do you guys recommend?
My goal is to reach 400rwhp with minimal lag time. While I'm going through my rebuild, I was thinking about doing flame rings. Do you guys think this is overkill for my goals?

Thanks for any reply,
Sean

[TurboKraft]

Hi Sean,

I would definitely keep the 964 cams.
Stock 964 cam timing is 1.26 +/-0.1mm, so while not perfect you were very close, and with a minor difference left to right.
Many people advance the camshaft more, and some cam grinders give a spec of 1.53mm.

Flame rings aren't necessary at this boost level. That amount of time & money & effort would be better spent on ARP head studs. If replacing the studs, you could replace the rod bolts at the same time and that makes the bottom end pretty much bulletproof.

If I had the heads off, I'd port & polish them before I'd flame ring them. More expensive, but much more beneficial. A complete job includes TK's billet injector blocks with a matching bore, port-matching the intake manifold, and port-matching the exhaust manifold. That's a heavy breathing setup with no loss in low speed drivability, just gains everywhere.

Good valve springs, good valve job.

No reinventing the wheel, a basic solid setup.

Tune the CIS so it doesn't run lean up top, and go drive and enjoy for another 65k miles.

[nocarrier]

I have a similar build to yours except for ported heads and EFI.

I'm not sure about changing the timing specs on the 964. Maybe someone else can chime in on that.

The 964 cam should give you more power at the top end.

I like the sc cam grind. If I were to change the cams. I would have my heads flow benched and the data sent to the cam grinder. For a custom grind for what I want out of the motor.

Right now, I'm running an sc scam (930s) set at 1.7

For 400hp, I wouldn't do the flame rings. You should be fine with a high quality set of head studs., rod bolts, etc.....

Get an AFR gauge, verify proper timing, check the plugs, etc.

[nocarrier]

oops, Chris beat me to it.

[Edelweiss]

Yes - we also tried both profiles, the 964 grind is not in any way a loss at the bottom but a reasonable gain above 4500 rpm.

By the way - follow whatever Chris is proposing; he is the man !

Best reg.

Dirk

[skimp930]

Chris, you always amaze me. As soon as I posted I got a call from Chris at TurboKraft to answer all my questions and give out recommendations I didn't think about. How do you find time to be on this board and get your work done. Again, Thanks for your help!

Sean

[TurboKraft]

Thanks!
Sometimes there's time to contribute to the board, and other times there isn't even time to answer the phone...

[skimp930]

Nocarrier/Dirk,
Thanks for posting. After speaking to Chris and reading your posts, I probably keep the cams and advance the settings as recommended. Also going with ARP head studs and do some port and polishing of the heads. Hopefully I can control myself and not go too crazy on this rebuild. I told my wife I'll spend X amount of dollars on this project but saved some on the side just in case.
Sean

[TurboKraft]

Similar project, 3.3L C2T, great results:

Forced to Deal with This

[Edelweiss]

Hi again Sean,

again - Chris is as helpful as kind and he knows what he is talking about.

Top on this planet when it comes to 930 etc.

Then - have a look into the mirror: you are the one with the beard, so do what you have to do and never ask your wife !

Go as crazy as possible, you just have this one life - do not waste it with pussy style boost and / or HP...

Best reg from Krautland

Dirk