edco

I pulled the cam cover on the driver side and put it at TDC “0/T” and here is what I found. Looks a tooth off to me, but I’ve never done a timing belt on a 928 so I’ll let you guys tell me if I have found the problem.

PorKen

It looks like the correct tooth, vis-a-vis the gear, but one or both cams could still could be misadjusted. (There is a ±1 tooth range in the gear slots.)

Bill Ball

I agree they look the same on both sides and the gears could be set differently versus the cams.

They do not look off a tooth. The leading edge of the front wide notch is right. Look at the back edge of the gear and you will see the small V-notch and it appear to line up with the V-notch on the backing plate. Still as Ken said and I agreed, that doesn't mean the gears are set the same relative to the cams.

Matt, if you are home today I can come over with Ken's cam timing tool and see what it gives us. Also, I have an IR gun and we can shoot the individual cylinders outlets in the manifold too.

Vlocity

I had a bank off by a tooth and that side also showed an across the board decrease in compression when we tested it.

Ken

Bill51sdr

There's usually a notch on the backside of the pulley that should line up with the notch on the backing plate if all is lined up properly. Do you have those and if so, where do they line up? It is the same notch you see when you look through the venting hole in the timing covers.

EDIT! Oops, shoulda read Bill Ball's post more carefully!

edco

Ok Bill just left and we used PorKen’s slick tool to adjust in the cams.

Driver’s side was 5 degrees advanced, that is the hot side. The passenger side was at zero degrees. We adjusted the driver's side back to zero. I'll report back later tonight after a test drive. I highly recommend this tool for anyone who has had their cam gears off, So now we are at 0/0 on both sides.

A big thanks to both Bill & Ken

PorKen

Cool!

5 degrees is significant. It's easier to advance, so I probably would have set the passenger side to match.

For future reference - with a cold engine, it's wise to set the right (US pass. side) cam one or two degrees retard, to compensate for engine expansion. If the engine is checked hot, then both sides should be zero. Also, it's good to rotate the engine a few times and recheck the setting.

Bill Ball

Yep, the driver side cam was clearly advanced 5 degrees while the passenger side was spot on. We could tell that someone had replaced the cam gears and they missed the mark a bit getting the driver side one lined up. It's hard to see in Matt's first photo but the stylus is in the 5 degrees advanced spot.

Ken has holes precisely drilled in the device. The pattern is shown below. The top hole below is the 0 degree hole. Then as you move to the left, that is the advanced side, zig-zagging along, you see the "x" where the stylus is in the 5 degree advanced hole.


There are a lot more holes for greater range than shown, but this gives you the idea.

Ken's tool is priceless and remakably easy to use. There is no way to "eyeball" the cam position this accurately. Ken provides a washer that allows you to lock the cam bolt to the cam while clearing the cam gear so you can move the cam while the gear stays stationary, held in place by the timing belt. What a piece of cake!

We did rotate and recheck the settings. We did have to readjust once. Yes, we left the passenger side 0 degrees as we think we found the major problem.

One slight oddity... We used the TDC cylinder 6 position included on the tool to check one time and it showed 2 degrees advanced both sides. Rechecking at TDC cylinder 1, showed dead on 0 degrees.

I replaced my cam gears 4 years ago without benefit of the tool. I tried to mark their position. Maybe I got lucky, but I am going to recheck this now with Ken's tool.

PorKen

Bill,

Nice writeup!

I checked the drawings, and I can't find an error. Is it possible you overshot the 0 | T slightly when you checked at #6? It only takes a little bit. It could also be parallax between the housing 'beak', and the damper mark - IE the angle at which you were looking when you rotated the engine to 0 | T at #1 and #6. I found that the water pump pointer is a much better indicator, but what'd ya gonna do?

It will be interesting to see what you find on your engine.

IcemanG17

Great write up guys........another great porken tool put to good use!

Is 0 the correct spec for the cams.....I thought Louie Ott did some testing and found 3 degrees was the best?

I wonder what mine is......Marc T checked and set it himself...or at least thats what the receipt says?

Bill Ball

2 degrees cam would be 4 degrees crank. I would think that kind of crank position error would be obvious. The crank pointer looked spot-on and we were careful about parallax error. I will check it on my car, but I won't get to it for a few days due to travel.

John Speake

Did the readjustment of cam timing cure the problem ?

PorKen

The V2 tool measures in crank degrees, Sahib.

PorKen

While changing my cam timing - again - I looked for any differences measured at different positions.

After setting the cam timing, I rotated the engine by hand, and using the starter, with the fuel pump fuse removed, to settle the belt. After a few turns, measurements with my V2 tool were the same at all points for the left cam, but the right cam was slightly variable.

In my testing, on a cold engine, the right cam moved about 1°, at #1 TDC. Measured at all other positions, #1 -45°, #6 TDC and #6 -45°, it kept the same setting, but at #1 TDC, it added 1° retard.

It appears that belt stretch, dependent on valve action, has an effect on the timing. While setting my cams I saw that it takes over 50ft/lbs to turn the 32V cams on a cold engine!

H2

Any follow-up on cam timing and overheating? I'm about to pull my belt covers and usePorken's 32Vr tool just to make sure my timing is still where it should be. I didn't heed Ken's advice and use the old belt when making the32Ver adjustments (I already had the new belt on).

Using the Made in China laser temperature checking tool, I could have sworn that the rear two cylinder's on the passenger's side were running hotter than the others. I did a leak down test on the engine saturday and all checked out about the same so no problem there. It was hard shooting the temp gauge to the header pipes in that area so I may have messed up the reading. I'm still working on the overheating issue. It's not serious, just between top white line and red...a track day would put it in the red. Unless I have a humongous air bubble I haven't been able to clear, I'm starting to suspect timing. The radiator flows water as fast as I think could be expected., the thermo is new and verified to be working right, new rad cap, etc. etc. Radiator backflush didn't kick much out. I hate to buy a new radiator or rip the one I have apart and then find that the problem is something else. At the first break, I'll use PorKen's great tool again. (Somehow I need to restate that last sentence before his woman reads this).

Harvey