82 CJ5 vacuum advance

82 CJ5 vacuum advance


Willis, VA
82 CJ5 258 4 spd. No mods
Hey all,

After trying to troubleshoot a leaky rear main seal and thinking it was excessive blow by causing my seal to leak and trying to eliminate all vacuum leaks I removed almost all vacuum and emission stuff. I still have the PCV hooked up to the base of the carb. Everything else has been removed or plugged. The 258 runs very well and idles no problem at 650 to 700 rpm.
I have always thought the Jeep lacked power at or above 45mph but just chalked it up to a tired motor since it is over 150K or so. I decided the other day to check the plugs just for the heck of it. They all were real white and or burnt like the motor was running lean or a vacuum leak or something was up with the timing. I adjusted the air fuel screws just like the Haynes said to. I have that correct. The idle and fast idle is set correct according to the book minus all the emissions junk. I checked the timing and it is at 6 deg BTDC at idle with the vacuum hose to the advance plugged. I am taking max vacuum off the bottom of my carb NOT from that vacuum fitting that was in the intake manifold. My question is this, when the vacuum line is hooked to the distributor and at idle the timing mark is about 15 to 20 degs BTDC I think. It is almost at the 12 o'clock position on the damper. When I squeeze the vacuum line while still hooked up the vacuum mark does not change. When I rev the motor the mark still does not move. I'm thinking if the vacuum advance was working on the distributor the mark would move when I squeeze the line and cutoff vacuum to the distributor or rev it. Am I wrong? If my vacuum advance is not working can I just order the vacuum advance that bolts onto my distributor or do I have to buy the whole distributor?


If you set the timing to 6* with the vac hose off and pluged, and it goes to 15 to 20 when hooked up, the vac must be working. Not sure why pinching it off doesn't change it. (yes you can buy just the vac can)
When you say it hooked up to the bottom of the carb. are you talking about full vac. or ported vac. In other words how much vac. is that fitting pulling at idle. It sounds like you have it ran to a full vac. fitting, ported should have almost no vac at idle.
If you pinch the advance hose with it still hooked up, you are simply trapping a vacuum in the advance diaphragm pot.

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