1990 4.2L Wrangler Timing Advance Question - Jeep Wrangler Forum
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Old 04-28-2010, 01:11 AM   #1
Join Date: Apr 2010
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1990 4.2L Wrangler Timing Advance Question

I set the timing on my 1990 Wrangler 6 cyl engine tonight.

I set it to 9 degrees at idle, no vacuum advanced connected - that seems right by the book. Then I turned the Jeep on and let it idle, but I could see the timing was advanced about 15 degrees at idle, and more as RPMs increased. I don't have a vac meter; vacuum seems sufficiently strong at idle and the advance mechanism moves a little with "mouth power"

What should the timing be at idle speed or a set RPM with the vacuum advance connected? Is there a metric such as 30 degrees BTC at 4,000 RPM?

Could this be a sign of a bad vacuum advance on the distributor? I see the vac advance moving as more RPM's are applied, but it doesn't seem to give a steady advance at a high RPM.

I can't find a spec for "total timing advance" to get any idea what the timing should be generally at any RPM with the vac line connected.

Thanks in advance.

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Old 04-28-2010, 09:21 AM   #2
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Join Date: Jul 2009
Location: wisconsin
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was th jeep up to operating temp that could cause it maybe
some say why i say
its a jeep thing u wouldn't understand
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