FRporscheman

The procedure in the wsm for setting proper cam timing looks complicated and I need special tools I don't have. Like for pressurizing the variocam. I don't want to buy them. Isn't it possible to use the exhaust valve lift measurements to set timing?

Anyway my car is quite sluggish compared to the other 968. And friends with 968s who have driven my car tell me it's lacking some power. I want to try tweaking the timing one way or the other and see if I can squeeze some more power out. I don't mind doing this over and over 10 times if I need to, but obviously I'd like to avoid that. That cheese head cam bolt isn't really going to let me open him 10 times, is he?

The car is lacking power, most notably in low rpm. It eats lots of gas, passes smog easily, and idles fine. I'm just wondering which way I should turn the sprocket first, cw or ccw?

PorscheDude1

I think there is a write up on this procedure on 968forums.

RajDatta

Arash you have PM.
Raj

FRporscheman

3 months later....

I reset my cam timing. My seat-of-pants test confirms that the car has the same level of power as my other 968, and a friend's 968.

I used no special tools at all, no dial indicator, etc. My first plan was to just try and err until I got it right. Then I devised a plan to simply use ONE dial indicator and set the proper exhaust cam position. Finally, I devised a method to do this without even needing the dial indicator. It's very technical and scientific, so please do keep up (sarcasm).

The reason the cam gear is adjustable is to allow for machined heads (which are shorter) or belt stretch. The reason they tell you to set the intake cam is because the chain may stretch over time (I guess). So step 1: slap in a new chain. Now I can just focus on the exhaust cam. The exhaust valves for cylinder 1 close 1 degree before non-firing TDC. I put the crank to non-firing TDC, using a dowel in spark plug hole 1. Then I turned the exhaust cam while watching the valve tappet. I turned it until the valve JUST closed. Then turned it a little bit more (about a degree?).

Took it for a test drive and it worked, baby.

Beforehand, the cam gear was at the end of the adjustment range. Now I forget, but I think it was fully advanced. Now, it is exactly in the middle of the adjustment range (makes sense, stock never-machined head). I'd figure at least 10 more hp in the low end. The top end feels about the same.

RajDatta

Congrats!
Nice mod there .
Raj

FRporscheman

I love how I used a stick of wood to tune my Porsche engine. And my eyeballs. It may not be perfect, but if perfect is Everest, and what I had was Death Valley, now I'm at the top of K2. High enough to feel good...

rdhayward

Thanks for the benefit of your experience.

I wanted to note that I had a hair less than 0.5cm of chain stretch, with just 105k on the clock.

Andial951

sounds like a much better mod than the "cereal box" mod...........

FRporscheman

I just conducted a fuel economy test. With the previous cam setting, I was averaging 300 miles per tank (full to reserve light). That works out to like 17mpg. Now I got 406.7 miles on 15.125 gallons which is about 27 mpg. And my car was filled with cargo (a wheel and 2 toolboxes) for about 300 of those miles!

Again, I don't know how close I got the timing to factory spec, but the power gains and 10 mpg more make me a happy camper. I bought a dial indicator and when I have time I'll try resetting things more accurately. I wish I would have done all of this sooner.

kwikt

After changing my belts and timing chain, my car seems a little sluggish also. This sounds waaaay too simple of a methodI've got the dial indicators. All I need is the time to do it.

Kevin

PorscheDude1

Perhaps your timing belt is off a tooth?

kwikt

No, I checked it at tdc and all marks line up.

FRporscheman

Smokie, I pledge allegiance to the flag!

RajDatta

Arash, so it definitely a lot better than before. Nice going.
Raj

N/a 944

Kick *** results Arash!