924Board.org

[GregSC]

Yeah, the crank pulley mark (more of a machine cut v-shaped indentation on the back rim of the pulley) lines up with the "pointer" indicator behind it, and the distributor timing mark lines up perfectly with the front of the rotor button at that same mark. It's just that the cam sprocket mark is a bit off. Maybe I'm just being a little OCD about all of it, but the other two marks line up so well that it concerns me that the cam sprocket mark does not.
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1981 931

[Fasteddie313]

Well, it can only possibly be off in increments of 1 tooth, so is it an entire tooth off?

Maybe put a new T belt on it just because..
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80 Turbo - Slightly Modified

[Paul]

Don't forget to change your oil, it's most likely full of gas due to all the failed start attempts.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[Carrera RSR]

The rotor arm in the distributor can be pointing in any direction after crank and cam are timed up. All depends how it was dropped back into it’s mounting by the last person messing with it. Most folks don’t care how it’s lined up, they just drop it in and the dizzy shaft spins on the cam as it goes in. Some of us do care and take several attempts to drop in so the rotor at tdc does point in a specific place to make everything easy. So never assume the rotor is in the right place.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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[Carrera RSR]

One tooth out on the cam will not cause a no start assuming the ignition is set up to suit. It will give you an advanced or retarded cam timing though moving the power up or down the Rev range.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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[GregSC]

It's definitely starting now, just took it for a short drive, so maybe I'm just being a little too anal about the alignment of the three different points in question. The timing belt is fairly new, less than a year for sure, and very few miles during that time. I put it on myself, something I've done on these cars a few times, and noticed the cam mark was off slightly before I took the old belt off (from my perspective) but seeing as how the car ran before the change, I didn't want to risk moving the cam sprocket without knowing how much I could without damaging the valves. Still wonder about that, if anyone with experience could chime in.

Concerning the number of teeth off in my perspective and me saying it was "a tooth and a half," that was only an estimate. I wasn't at the car at the moment and didn't measure it exactly at the time, just letting those that might want to be a help that it seemed off around that much.

That's a good suggestion about the oil change. It was cranked over quite a bit trying different ways to cure the electrical issues, thanks!
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1981 931

[!tom]

If you're concerned about damaging the valves, just turn the motor over by hand after a timing adjustment. You'll be able to feel interference without causing damage.

The starter might damage things if the timing is out, so do it by hand first.
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78 924 NA
5-lug

[924RACR]

Also note that when you change the timing belt, the marks may be aligned when you slip the belt on but if you don't take up the slack properly just setting the tensioner can be what pulls them out of alignment, one tooth is usually the result.

Of course boost will hide the lack of torque from the timing being off...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jacobroufa]

This tip definitely helped me out Vaughan, thanks! I just had this exact thing happen to me, and caused a hard to start hard to keep running situation.
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1980 Porsche 931
1981 Porsche 924 Weissach

[Carrera RSR]

Cam timing being 1/2 or 1 tooth out won't affect starting or running. But the knock on impact on a Series 1 distributor will be enough to cock up the timing and affect starting and running
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252