I've read on the forum that my problem could be caused by the distributer bushings going out. It seems like mine are OK so I'm at a loss to what my problem is. I have a smooth idle. When I adjust the throttle to hold the RPMs at 1600, they will fluctuate up to 200 RPMs. Then, when the electric fan kicks in, the RPMs fluctuate up to 300 RPMs. When the fan quits, the RPMs go back to the 200 fluctuation. My Dizzy is a Hitachi pointless and has very minimal side to side play but has about a 1/16 of an inch vertical play. The vacuum advance doesn't leak. When I got my 82 Sub 2 years ago the Dizzy had a Philbin sticker on it so I know it had been rebuilt to some degree at some point. It was very dirty when I got it so I took it apart to clean it. As far as I can tell I put it back together correctly, adjusting the air gap to spec. I had an old Sub mechanic take a look at it and he said that he thought the bushings seemed acceptable. I have a new alternator and I have tried 2 different coils that gave me the same results. Any thoughts would be greatly appreciated.

The correlation to the distyshaft bushing and the RPM's is just to the tach gauge. It really has no effect upon the actual RPM's of the engine. When the fan turns on, theres a draw on the alternator and the RPM's will increase to adjust for that increase.

The fluctuation could be due to a vac leak or some other odd occurrence which plague older Soobs.

Interesting. I assumed that when the fan kicks on and starts using up power the RPMs should decrease a hair. But it sounds like the car compensates and is able to boost the RPMs instead? I'm pretty sure I don't have a vacuum leak. I've doused every intake connection with carb cleaner and had no results. And my idle is pretty steady with maybe a 25 RPM fluctuation. I've also hooked up a vacuum gauge to the manifold giving me a good solid reading at idle and a consistent reading at 1600 RPMs "the vacuum gauge did fluctuate slightly with the RPMs". I'm going to disconnect the cruise and brake booster next to completely rule out a vacuum leak. I would also like to rule out all electrical problems. Any suggestions are welcome.

Edited January 4, 201016 yr by All4EA81

Just to give a little closure to anyone doing a search. My EGR valve, which was disconnected, was leaking intermittently. Sometimes it would suck the carb cleaner I sprayed on it and sometimes it didn't. I fixed it by making a block off plate to replace the valve.