Timing marks jumping - JeepForum.com
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post #1 of 4 Old 11-22-2007, 11:51 AM Thread Starter
Havasu Living
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1980 CJ7 
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Timing marks jumping

1980 CJ7 258 with about 100k miles. Had the head redone several years ago. I warm up the engine hook up the timing light. While I watch the marks they stay steady for several seconds then the timing will jump to about 15 btdc for a revolution then go past the 0 timing mark by 6 degrees for a second and then return and steady out. This repeats over and over. It's not a purring engine, but pretty good at idle.
Would this be a worn out timing chain? Thanks

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post #2 of 4 Old 11-22-2007, 12:11 PM
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post #3 of 4 Old 11-22-2007, 03:57 PM
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do you have the vacuum advance disconnected? are the mechanical advance springs good? if you answered no to either one of those questions check there first then suspect the chain

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post #4 of 4 Old 12-09-2007, 04:55 PM Thread Starter
Havasu Living
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Posts: 342
It was the dizzy shaft. It was wobbling severly. Not sure why yet. Anyway installed a spare and now working like a champ.
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