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When I timed the cams on the 90 I was kind of surprised that with the crank a TDC the cam notch was retarded about one tooth. According to the 32v'r the cam is retarded 2 degrees. Before there wa a 32v'r I matched the notch the 'V'. This is the first time I can remember there being a discrepancy.
Is this unusual?
I have had the car running but went back in to re-tension the belt after I got a t-belt warning. The position of the cam is exactly where I set it when the engine was on the stand.
Here's a bird's eye view. The belt is marked where the notch is on the cam gear.
You are not supposed to use the notch to set the timing. They are only good to get you in the ballpark. The proper way (before Ken's tool) was to pull the cam covers and use a dial indicator on the cam. The WSM has the procedure but it's a real PITA to do it that way.
Maybe I am still half asleep still on only the first cup of coffee this morning but when the engine is cold the 5/8 bank is supposed to be at zero and the 1/4 bank at -2 [correct?] and your photo,albeit not entirely a clear angle suggests 1/4 is at minus 2. Am I missing something here?
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
The timing according to tool is spot on. At the factory they were set up with notches aligned, but if subsequently cam gears removed/replaced, you lose that alignment as the mounting holes are slotted and allow for some rotation of the gears. That's another reason why this is such an invaluable tool
The timing according to tool is spot on. At the factory they were set up with notches aligned, but if subsequently cam gears removed/replaced, you lose that alignment as the mounting holes are slotted and allow for some rotation of the gears. That's another reason why this is such an invaluable tool
Actually, the notches are a fixed postion, determined totally by the belt and the distances between the gears. The mounting holes that are slotted allow one to move the cams in relationship to the cam gear's fixed position.
Note that the super stretchy "aftermarket" belts make notch alignment further off.
The notches are almost always off some....rarely lining up exactly. This one is extreme.
It's a Gates belt sourced from 928sRus. Interestingly, the belt was very easy to install. Much easier than any other belt I can remember. I have a Porsche belt on the shelf. Never thought about comparison.
It's a Gates belt sourced from 928sRus. Interestingly, the belt was very easy to install. Much easier than any other belt I can remember. I have a Porsche belt on the shelf. Never thought about comparison.
Apologies for not grasping your dilemma yesterday - clearly I needed more coffee!
On my 90 S4 motor the cams were timed with dial gauges and I used the 32VR kit to verify the timing which visually and as per the 32VR was spot on so I have the comfort of [hopefully] knowing my system is calibrated correctly and can rely on the 32VR to give me accurate results.
Your dilemma now is whether to accept the 32VR result or go back in and follow the WSM method for the 1/4 bank [at least] to check calibration.
As a matter of interest where is the cam sprocket adjustment - in the middle of the adjustment range or more to one side of the slot? This might give a clue as to whether the cam is a full tooth off relative to the belt. Your photo suggests that at the moment the sprocket is about half to three quarters of a tooth out relative to the notch.
I have the same problem with my 86 as well. 1-4 off by a tooth. 5-8 almost perfect.
I'm about to do the belts on both my 86's. Should I use the Gates racing belt or are the standard belts ok?
It's good to know I am not alone on this. My plan is to see where we are after 1500 miles when I re-tension the belt. I have a 91S4 queued up for a head gasket replacement and a new Porsche timing belt set aside for it. It will be interesting to see what happens.
Mine hasn't had the belt done since '96. I got the engine to temperature and checked again and it was the same. I'm going to buy the 32V'r and do the belt and see what happens after a belt change. Do you have the standard tensioner?
05-02-2016, 09:40 PM
Porken 32v'r VS cam notch
George Layton March 2014
