I started simple first with this. I checked to make sure the vacuum connection on the carb and the distributor were properly attached. I took it out for a drive to get it well warmed up and adjusted the idle when I got home, so it's now exactly 1000 in gear and 700 in idle. Took it out the next night on another long drive and brought it home, no run on. I didn't mess with the A/F mixture, just the idle screw.

I will have a look at the timing next time I've got it out. I'm just wanting to try one thing at a time to see if it works, rather than do 3-4 things and wonder which one worked.

 

I think that 1000/700 rpm at idle sounds about right. If you're lucky the problem is solved...:thumbsup:

 

Also make sure that the fuel tank has an open vapor vent. Tank pressure building up could cause it too. Sometimes the vapor line gets insect nests in it, or capped off at the tank port.