Cam timing question...
 

In my never-ending quest to get this new engine running correctly, the wrench discovered that cam timing was off. I have the WebCam 20/21 grind. WebCam's specs are between 1.9mm-2.2mm. Wrench discovered that left bank was at 1.9 and right was at 2.05. Obviously, they need to be matched. This Friday I'm taking off work early to watch the wrench do this job. I'm running rich and I'm concerned about passing emisisons inspection in 06/04. Should I have him bring the left bank up to 2.05 or the right bank down to 1.9? Although it would be nice, having more low end power is my last concern right now. Thanks.

I wouldn't worry about advancing or retarding the cams. I used to do it but now I think that within the "spec" range, the difference is too small to make a difference. Just get them even.
-Chris

Hey Chris..
I have always timed under the assumption that the higher the setting, within spec range, the more advanced the timing is.. then someone posted that the lower the setting number the more advanced the cam is.. you have any comment on this? ................Ron

Ron,
Yes, you are correct. Using the factory method, we're measuring valve opening so if the valve is open further (higher setting) it means the valve is opening earlier i.e. advanced.
Comment: I think of cam timing as moving the torque peak around. If I advance the timing, I move the torque peak lower in the RPM range. If I retard it, I move it up in the RPM range. Horsepower is a function or torque and RPM so the same torque at higher RPM will result in more horsepower.
-Chris

Ron - here is what I discovered during my first timing endeavour 10 years ago:

-advance the cam timing (move to the upper end of the spec range). RESULT: power and torque peak at lower RPM.
- retard the cam timing (move to the lower end of the spec range) - RESULT: power and torque will peak higher in RPM.

As a note, I have also read that even though you effectively move the peak, you will not notice that much difference in terms of driveability. For that reason, I always shoot to get both banks close to even in the middle of the spec range.
Good luck,

This is enlightening for my feeble mind. How much of an issue is created by difference in my two banks' settings? Car pulls nicely to me, but I know they need to be identical.

the difference you have certainly could be closer, but it won't make much difference. that spec seems kind of high for an SC that's normally timed at 1mm. did you call webcam? i can't remember what i set the last one to. superman and doug zelke both used them. you could e/mail them.

I don't know how much difference it makes. I've heard that the newer Porsches ( 996 I think) aren't timed that closely. I seem to remember Bruce A. saying something about Jerry Woods finding them not very even and that setting them "correctly" resulted in an improvement.
On "normal" cars, the timing is a much courser deal I think. Sort of like the "initial cam setting" you do before you start moving the pin around.
-Chris

Well, let's see...adjust one side for low end torque and the other for high end torque. Result? Torque throughout the RPM range. Would'nt that be nice?
You know Richard the entire adjustment is started by setting intake valve clearance for cylinders 1 and 4. What if your initial setting are a little different? I would not worry too much about a very slight difference between the two banks. I really feel there are so many other variables involved to account for slight differences (how tight was each chain?, Was each chain PRECISELY the same tension, Valves adjusted PRECISELY the same? See, you can go on and on.). Get the two banks close and button her up.
Regards,

Chris/Tom
thanks for the confirmation..

I always set advanced. partly because it's a street engine, and partly to allow for chain wear..............Ron