[aermotor]

I have never had an A engine totally apart. My question is - can a model A "jump" timing if the camshaft thrust plunger is not doing it's job because of a weak spring or some other reason? Reason I ask is because after complete trouble shooting the timing and entire ignition system the engine runs fine at idle and a little above. However when the advance lever is pulled down the engine will "bog" down and eventually quit. The distributor plate lever is touching both sides of the housing at full advance and full retard. Note, again, that this is happening with the advance lever being pulled down from full retard. I did pull the distributor shaft housing and shaft gear and could see no problems. The steering box is 7 tooth so no adjustment is available there but the dist. plate arm adjustment is okay as stated above. Timed with NewRex tool and once again the entire ignition system was trouble "shooted" and no problems noted. The carb was taken apart and rebuilt 2 times so carb. problems should not exist as the condition is all related to the spark advance - so I think. I have no way to know if it is going more retarded or advanced when it bogs down. I know how to determine with a timing light but I don't believe they even existed in the model A days and this problem should be fixable without one. The problem started with an erratic miss which could not be pin pointed to any one cylinder and occasional back fire when rapidly letting up on the gas pedal at higher RPM's when it was running. So I fixed it till it's really broke. O, yes the point gap is .017 and rotor to housing contacts all the same @ .025.

John

John