I've been trying to find the source of a mild vibration around 1000 rpm in my Cutlass 307. Otherwise the car runs fine. I've replaced the cap, rotor, plugs, and wires. When I check the timing, the mark fluctuates back and forth between from about 26* to 16*. Sometimes it slowly creeps up and down, but occasionally it jumps. Sometimes it stays at the same mark for a while. What are the most likely causes? The car and engine have 54000 miles.
What could cause the timing marks to constantly move?
- Thread starter jamesejam
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Maybe the timing chain is loose or the dist. gear is messed up. Also, make sure the distributor is securely mounted.
jamesejam said:
It would have to be physically loose to make the timing jump around. If the outer ring slipped it would not cause the timing to fluctuate, you would just get the wrong reading.
you should be plugging up the vacuum advance when checking timing but if your not perhaps a small vacuum leak on the advance or the advance is sticking
pontiacgp said:
Dang I forgot about that. Could it be possible that you dont have the hose going into the right port on the carb?
I didn't plug the vacuum advance as I thought it wouldn't make a difference...so I need to plug the advance that's attached to the distributor, right? Do I need to also plug the hose attached to the carb?
Is there a vacuum advance on a 1987 distributor? I looked everywhere and can't find a vacuum hose, there's just electrical wires attached to the distributor.
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