hunterpeaks

Hi Good folks-

I have a new to me 964 - Race Car. I have checked cam timing and the passenger side has 1.6 and the driver side has 1.74 for Cam timing. I have had one of the local guru's tell me that it should be retarded to .9 -1.0 for more top end. But, not sure this makes sense. I am mainly in 2,3, 4 for most of my PCA races, and only in 5th for 5-15 seconds in the longer tracks like VIR.

Any opinions?
First off, I am going to put the cam timing as close to even as possible, but want to do it right and hopefully someone here has some ideas. Thanks.
Hunter

crg53

First off you have to know which cams are in there, they should come with timing specs.
If they are stock cams, the setting is 1.26, but you can move that around to suit your need. Your mechanic is right in, if you retard the cam timing you get more top end, if you advance, more bottom end.

LouZ

Being at 1.6 & 1.74 suggests that these are not stock.

Standard cam timing is 1.26, +/- 0.10. Under 1.26 gives more top end, while over 1.26 provides more low and mid-range punch. I am set at 1.35 for the track, because, there are a lot more turns that can use the low end power, than being maxed out on a long straight.

hunterpeaks

Thanks guys. So, a quick vocabulary clarification. And excuse my lack of knowledge, but just want to make sure I understand exactly. So, when you speak of "TOP END", that means more power from 5000-to 6800 redline, right? Or does that mean more power at High speeds in 4th and 5th gear at the end of the straight away?

I need more power from 5000-6800 as that's where most of the race is raced and less down low, as my rpms are almost never below 4500.

Hunter

LouZ

As explained to me by my PCA local gurus, advanced cam timing produces more TORQUE, and retarded provides more HORSEPOWER.

More torque = quicker RPM gains from 5000 to 6800, which I feel is a benefit at the track.

I heed the old saying: Torque for GO, Horsepower for Show

ras62

Worth noting that timing check/changes should be done with the manual chain tension tool in place not the normal hydraulic one.

Steve Weiner-Rennsport Systems

Good advice!

"Area under the curve" is EVERYTHING, and especially when you cannot use close-ratio gears.