RajDatta

This can be used as well but with the other method you have everything locked. The back plate method is a good backup if you mess up since it will always have dirt marks in circular form from the cam pulley. If you all your dirt marks up, your timing should be back to old.
Raj

RajDatta

Like I said, its only necessary if you are not happy with the performance of your car or someone didn't do the job right. I doubt the factory didn't have the cam timing right because they notch the cam pulley after they get the timing down. That is how the pulley was notched. Just because someone can't backtrack their records or have no way of knowing if this sort of work was ever done to the car does not imply the factory got the timing wrong.
Yes, it will put $$$ in certain people's pocket by getting this sort of info out there so I do understand their intentions.
Raj

RajDatta

You should change the chain and pads definitely. I would do it soon.
Raj

FRporscheman

I've got 223k on an original variocam tensioner unit and it works fine. They love you long time. But pads and chain at 104k should be changed some time soon. They will last longer, probably.

Would chain stretch cause a perceptible difference in performance? My car lacks power... maybe it's not only the timing, but my 170k-old chain.

luckett

Probably not, but depending on relative wear between the chain and cam gears, it could alter the timing slightly.

PorscheG96

Let us know if your engine feels more powerful after you reset the cam timing w/ your vario tensioner maintenance.

FRporscheman

Will do! I need to order some dial indicators. I don't understand why the timing is even adjustable. Why didn't they just make the cam gear with a narrow keyway, like so it only goes on one way, the right way?

Maybe because chain stretch would necessitate adjustments to get the intake cam corrected...?

968workaholic

How would you be able to buy a new cam sprocket and time it if you had to put the notch in it yourself? I have worked on two cars that have been off from the factory. One had 25,000mi and the other one had 19,000mi. So I doubt that it would have been anyone elses fault but the factories. Which makes sense if you consider the mass quantities of engines that Porsche built.
Arash, in order to make up for manufacturing differences and other things, the sprocket is slotted so that the timing can be dialed in for that specific car. It also doesn't help that these cars were built by Germans either.

RajDatta

New cam pulley comes without a notch. You time it with dial gauges.
I understand you are Mercedes factory trained but 968 factory manual has a section just for this under Volume I (engine) on page 15-7. Go have a look.
Were the owners the original owner? I know one of them is definitely not and its well documented how there were vibration problems for months that could not be sorted out. Since the blame was layed on the mechanics inability to time the bs belt, who is to say, he didn't mess with timing to troubleshoot.
Sorry, I don't buy it.
Raj

968workaholic

Well the one owner was, and the other one wasn't. So at least one of them hadn't been opened up yet. Im not trying to argue about it, im just saying that some cars were done more accurately than others, thats all. As for the mark on the sproket, I stand corrected. It doesn't make sense though why they would not just put the mark on the gear when they make it. Seems like a wasted step to me. You learn something new everyday.

RajDatta

Fair enough.
Regards.
Raj

CarbonRevo

So is it possible to swap 968 cams into an S2 and see gains?

RajDatta

The advantage is with variocam and slightly bigger valves. If you change your harness and it works on a S2, you might. You should also look at it as a system, maf, dme etc.
I think S2 compression is also .1 lower than 968's so its bunch of things, not just cams.
Raj

968workaholic

The S2 head doesn't have the proper mounting points for the variocam assembly. If you look at the specs for the S2 cam and the 968 cam, the S2 falls right in the middle of the base and torque timing of the 968 cams. Meaning that there wouldn't be any real gains from just switching the cams. As Raj stated, there are many factors that make a difference, even the intake manifold has a part in the power differences.

FRporscheman

The best part to steal off a 968 would be the 6-speed transaxle.

Don't steal mine.