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post #10 of (permalink) Old 06-30-2009, 01:19 PM Thread Starter
USMCYJ
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Join Date: Feb 2004
Location: Arizona
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WOW! I just spent the last hour writing a reply and it all went away somehow when I went to post it. Basically, I replaced the power valve with a 7.5. I must have forgotten to replace the old de-formed orange one way valve in the accelerator pump housing initially, unless rebuild kits come with 2 The shot is now stronger than before but still shoots just after a VERY slight movement in throttle plates. I don't think it is of a huge concern though, I could be wrong. I also replaced the 6.5 PV with a 7.5. BTW, when replacing a Power Valve, make sure to use the THICK circular gasket. The thin one will create a leak. Found that one out the hard way. It's not the original problem though. So once I got those issues figured out, and the idle mixture adjusted, I drove it and it did not seem to stumble quite as bad, at all really. But there is still a lack of power...it's a Jeep, right? True, and I don't expect to run 9's on the quarter mile by any means but I believe there is more there...

RRich: you are one of the gentlemen I was hoping would reply with your seemingly endless knowledge...but you have me confused. I know quite a bit more than I may put off about engines and how they work, how to set timing, idle mixture, etc.(obviously there is a lot more to it than that). You said: "2. Check the advance - you said 10 degrees at idle - that must be with the distributor vacuum disconnected! The distributor vacuum MUST BE PORTED VACUUM - near 0 at idle, smoothly progressing as the R's are raised."
Ported vac.-got it, 0hg at idle, progressively gets stronger as R's increase. Manifold vac decreases as load increases. Therefore, ported is used for the distributor to help advance timing as R's increase.
that being said, why would having the port disconnected make a difference when setting initial timing advance? Is 10 a bad number to go with?
About mechanical and vac advance...should vac advance occur first, and then mechanical? Is that backwards? Or do they work together at the same time? I ask because the advance jumps in quickly, up to I believe 24*around 15-1600 R's, and then slowly raises from there to umm, not sure. Plugs are regular autolite gapped to .035. I never use "high performance" plugs. Always mfgr recommended.

Not sure if my carb is a 2100 or 2150 now. labeled motorcraft on the top of the carb, but stamped 1.08. I'm hesitant to say that it makes a difference, I don't think so.

Thank you to everyone who replied. Very useful. I need to change my profile, not in AZ anymore...I'm in Missouri.

'88 YJ
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