Another quick vacuum advance question -

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post #1 of 4 Old 02-04-2014, 11:16 AM Thread Starter
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1986 CJ7 
Join Date: Apr 2010
Location: Huntsville, Al
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Another quick vacuum advance question

So i just got done installing a motorcraft 2100 and a new air intake on my 86 258 t176 i havnt done the nutter yet. I bought it all from gronk the guy on ebay. Ive seen some complaints about him I didn't have any problems id buy from him again. But anyway. Im down to fine tuning it. Ive fond that the jeep runs awesome with the vacuum advance unhooked. When i hook it up to the port on the carb it stutters and there's a small pop coming out of the exhaust no matter how I tune it. Should i try to hook it up to the manifold vac and re-time it. Or can i just leave the vacuum advance off without destroying the motor. its not a daily driver so the only concern i have is the life of the motor not gas mileage. Im definitely not a mechanic so maybe someone with more experience could help me out.

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post #2 of 4 Old 02-04-2014, 11:30 AM
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Location: Elbert
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First, you should set timing with the vac advance disconnected, and the vacuum source plugged. Some guys mistakenly plug the vacuum canister not the vacuum source. This will be the initial timing you should use regardless of what vacuum source you use for the advance.

Second, I recommend you hook the vac advance to manifold, not ported. This will add advance at idle when your engine needs it, and produce a smoother more reliable idle.

You can run without vac advance, but combustion temps will be higher and your engine will be less efficient under light load driving situations.

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post #3 of 4 Old 02-04-2014, 11:45 AM
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1984 CJ7 
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Sounds to me like you may have the vacuum advance diaphram on the distributor busted. Hook it back up to the carb, and clamp the line to the dizzy shut. If it runs smooth, you have a vacuum leak through the dizzy when it is hooked up.
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post #4 of 4 Old 02-04-2014, 04:47 PM Thread Starter
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1986 CJ7 
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I ended up hooking it up to the manifold vac and it runs a hell of alot better. I still need to re-time it but it only sounds like its off a couple degrees. luckily this was an easy fix.
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carb , motorcraft , vacuum advance

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