acme,
Maybe I still don't understand. With the truck sitting in the driveway...you grab the distributor and twist it with light moderate force..it should not move at all. The vacuum advance unit has a spring in it that is suppose to hold it very firmly in a base position. If you can freely turn it as you indicate, either you are eating too many Cheerios, or the vacuum advance unit went south. This is the CPU on the truck, it must be accurate and tight!
Everything on the exhaust side is "after the fact"..I wouldn't waste a lot of energy in this area.
Stuart
