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

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!

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.

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.

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!

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

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

don't try to over analyze it.

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

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

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

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

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.

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...

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

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....

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.

the 3.0 i bought had a broken spring.


sure the noise is not spark knock??
what octane gas do you use? how about ignition timing?

I've always used a minium of 98 octane some more. i think it's shell v power a 100 octane gas.

It could be broken spring. I am taking down the engine next week, My timing is just not right i cant find any bits of metal in the oil and oil pressure is running good at all time so a conrod bearing is highly unlikely, valve springs why not?

I might do a top overhaul at the same time.

OK, has anyone tried to advance one cam and retard the other to try to broaden the torque curve? Maybe someone has done this and can post dino numbers.

what, so one side of the engine has power at low rpm and the other side at higher rpm? pure genius!

Never heard of that method i rather advance both!

JW,

What were your customers sc l/r timing i got a bad one 0.85 and 1.12. Both out of specs.

at the least, i would think the engine would run rough, that is why i think the L to R setting is more important.

my cams were advanced a lot (15degrees) by the PO. the car was almost undrivable. i could not floor it, nor run it past around 3500 rpm without spark knock. retarding the ignition timing, a lot (thats what led me to check the cams), did help and gave me maybe another 1000 rpms. but, i did have other problems. mainly one injector was only putting out half the volume of fuel the others were due to a bad injector line. my point, spark knock if not a broken spring or maybe a tensionor or even cam timing?? maybe the guy that did my cams did yours;)
i would try to find the problem brfore you tear it down, or at least eleminate some things. how is the ignition timing? advance working as it should? fuel pressures right, fuel mixture right?

As I said in post number 3, the cams can be timed exactly to each other and smack on the Porsche specification.
You can adjust a cam as little as 1/10th of 1 degree.
This compares to the pin and sprocket holes of 1.4 degees.
Our friends at Porsche knew what they were doing.
Mike at MBE Engineering knows all about it.

dont try to put the pin in a hole next to the one it came out of. that is a bigger difference in degrees, try one opposite of the one it came out of.

Does anyone here have a left and right reading?

depends on engine type number. 930/10 is 0.9 to 1.0.
930/16 and 930/17 is 1.4 to 1.7.
engine type number is forward of the oil temperature sensor and to the left of the oil pressure sender, on the flat area.

that was tongue in cheek, by the way.

T77911S,

Quote "dont try to put the pin in a hole next to the one it came out of. that is a bigger difference in degrees, try one opposite of the one it came out of."

I'll file your post #28 along with John Walkers post #24. :).