How closely matched are your cam timing(l/r)?

[Peter Seow]

I know they cant be perfect and we all want them to be as close as possible. i am going to do my chain tensioner this week, if there is any measurements or adjust this is the chance to do it right!

[Vin-barrett]

What will probably happen is one hole the value will be to low, and the next hole will be too high.
error to the higher number for a better running engine.

You may second guess yourself and repeat the procedure over and over again only to end up in the same holes you were in 2-3 tries ago....

The two sides may very well not be exact but it doesn't matter. Just get the two sides as close together as possible.

Don't make yourself nuts over it.

[2.70Racer]

I agree that we often worry about that 1/10 of a degree difference when timing cams.
Generally it isn't a big deal.
HOWEVER, you can get the timing left to right much closer than you suspect.
A classic case is the left side is smack in the middle of the specs, but the right side seems to straddle the spec. That is in one hole the cam is low in the next hole it is high.
To get back into the middle of the spec, loosen the right side chain and jump the chain 5 teeth at the cam sprocket.
You will be operating on different holes since you moved the sprocket so far. The 5 teeth will get you to the middle of the specification.
All this has to do with the odd numbers of holes in the cam sprocket.
I'm not getting into all the why it works, done that elsewhere here.
Suffice to say the cam can be timed to any of 7,000 different increments of a 360 degree circle.
This is not black magic, it is sprocket engineering.
The folks at Porsche would never settle for unmatched cam timing, you shouldn't either.

[rw7810]

PS: I hope you know you can replace tensioners without having to retime the cams

[Peter Seow]

Originally Posted by rw7810

PS: I hope you know you can replace tensioners without having to retime the cams

yes i know but once they are changed the cam timing will change!

[stlrj]

Originally Posted by Peter Seow

yes i know but once they are changed the cam timing will change!

Not so! Replacing the tensioners does not disturb the cam timing.

[Peter Seow]

Originally Posted by stlrj

Not so! Replacing the tensioners does not disturb the cam timing.

But if the tension is higher with a new tensioner, timing will advance.

[john walker's workshop]

don't try to over analyze it.

[BK911]

Timing may not change, but how do you know it was right when you started? Perfect time to check and adjust if needed.

[Peter Seow]

Originally Posted by BK911

Timing may not change, but how do you know it was right when you started? Perfect time to check and adjust if needed.

Exactly it might NOT be right so i reckon it's a perfect chance to get it right along with adjusting the valves!

Does anyone have a sample timing for an sc like left 1.0 right 1.05

I know someone else with a timing of 0.92 and 1.12

I was thinking of 1/10 of a degree difference like 0.92 and 1.02 would be more acceptable or best is a match like 0.98 and 1.02

[kens_74_911s]

Originally Posted by stlrj

Not so! Replacing the tensioners does not disturb the cam timing.

Agree main sprocket pulls the cam sprocket - chain under tension - timing fixed based on tooth CL. Tensioners just pick up the back side ( un-tensioned slack) -Ken

[signature65]

links are links....they dont change once the pin is set. Unless you let it jump a tooth you are fine.

[tobluforu]

I tried everything to get each side to match a while back, but could not.

[T77911S]

this is just my opinion. but i think getting the cams the same is more critical than where they are set. ok, calm down. that is just the spec porsche chose to use and i am not suggesting to set them anywhere. after all, look how much porsche moved the spec around for the SC. you could decide to advance the cams outside of what porsche set for the spec, as long as you check for clearance. take my car for example. my cams where advanced 15 degrees by the PO. not becuase they wanted them there, i think they read the dial backwards. but, they where both the same.

if the cams cant be set the same, how much does the valve adjustment effect this. say one side is exactly .004, but the other was .0045.

[Peter Seow]

Yes, how does the change in valve clearance affect the cam timing. I think there is a change. I guess my sound problem was nothing to do with the valve tensioners it's due to the valve clearance...

[T77911S]

what sound? tensionors tend to be noisy when you let off the gas

[Peter Seow]

A loud clatering sound but it only when hot and under load. Initially i thought it was the chain tensioner. Thne sound quitens down when you let the gas off so it not the tensioners.

its a valve clearance/rocker arm issue. Hopefully i dont have a bent valve.

[rw7810]

Originally Posted by Peter Seow

A loud clatering sound but it only when hot and under load. Initially i thought it was the chain tensioner. Thne sound quitens down when you let the gas off so it not the tensioners.

its a valve clearance/rocker arm issue. Hopefully i dont have a bent valve.

That sounds like a failed tensioner to me....

[john walker's workshop]

SCs break intake valve springs a lot. when each cylinder is at valve adjust position, if you can push in on the rocker with your fingers and compress the spring fairly easily, it's broken.

[Peter Seow]

Originally Posted by john walker's workshop

SCs break intake valve springs a lot. when each cylinder is at valve adjust position, if you can push in on the rocker with your fingers and compress the spring fairly easily, it's broken.

Might be i am going to check on them this sunday.