I can get my 1981 XJ6 to idle correctly and run good by adjusting the timing. If I use the idle speed adjustment screw it has no effect. If I screw it in all the way or out it does nothing. I have take the idle adjustment off and cleaned it out and it look good. How does it work and what is the purpose of the over-run valve. thanks for any input...Jerry

 

The idle adjustment works by letting more or less air into the engine.

The air distribution block might be clogged, or you have a larger amount of air coming in from another source that masks the effect of the idle adjustment screw


Cheers
DD

 

OK Thanks Jerry