Vacuum Advance

[TBP]

Everytime I hook up the vacuum advance hose to the distro from the carb, the engine starts to run like crap. I disconnect it, and plug the ports and it runs great. Any thoughts? Is this even a problem?

 

[ForceFed70]

Well, the vacum advance was only ment to help with fuel economy and emmisions, so not using it won't hurt anything.

The only reasons I can think of for the vacum advance making it run poorly:
- Too much timing advance (try retarding your timing a little)
- The vacum diaphram has a leak which in turn is causing a vacum leak.

 

[bnickel]

sounds like you are hooking the advance hose up to manifold vacuum instead of ported vacuum, some carbs have straight manifold vacuum at the port on the side, some holley and even the autolite 4100 are that way. for the advance to work correctly it HAS to be connected to a ported vacuum source.

 

[Max Power]

I would guess that there is a vacuum leak. Adding advance to an idling car rarely makes it run like crap unless the initial timing is set waaaaaay advanced or a mechanical weight is stuck in full advance. I mean, you need a LOT of advance to make a car idle poorly.

 

[zookeeper]

Time for a new diaphragm is my guess. They do develope leaks and cause the condition you describe.