vacuum advance causes engine to die
 

Need help with this one. 62 Ford 352. Starts and runs fine for about 20 seconds then runs really bad and feels like timing is out. Disconnected and plugged vacuum advance. After warming up it smooths out on its own and the engine runs fine. Timing is dead on and running smooth when warm. When I plug vacuum line back in it kills the engine and wont start with the line plugged in. Any suggestions?

Sounds more like a choke issue. The vacuum advance does not come into play if the engine is not started yet. The only thing may be if there are bare wires in the distributor and when you are plugging in the vacuum advance you are somehow shorting something.

Test the diaphragm unit, it probably is blown and leaks air when the engine pulls vacuum on it.

Bogie

I agree, sounds more like the advance can is shot and its causing a vacuum leak when you plug it in.

Bruce

I dont think this would cause a no start but I never say never

Turns out the advance mechanism was stuck and wasn't advancing. I loosened it and now its working, started and ran fine. Only problem now is that it wants to die on slight acceleration, runs fine at idle and more acceleration or full throttle. But easing out of a stop wants to back fire and die. Timing is still good.
Any clues?

Is the accelerator pump shooting fuel the moment you move the throttle? It should be giving a shot instantly.

Do you have the original single diaphragm vacuum advance and points distributor? Is the vacuum advance retracting when vacuum is applied. Does it HOLD the vacuum? Be sure the vacuum advance is moving the advance plate in the distributor when vacuum is applied. They can stick same as the mechanical advance. Try switching the vacuum advance hose from whatever it's on now (ported or manifold).