Is the stock vacuum advance adjustable?

[S-Car-Go]

I just installed in a Crane electronic ignition with a duraspark distributor. Set it up with light springs. Initial timing is 12 deg, initial + mechanical is 41 deg at 3,000 rpms. It fired up and runs great in the garage. Tried to drive it and it fell on it's face and backfired out the tailpipes. Disconnected the vacuum advance and it runs fine.

Can I adjust the factory vacuum advance? or do I need to buy an aftermarket ($30)?

 

[thehueypilot]

Factory advance in not adjustable. Is your vac advance hooked up to a ported (timed) vacuum source?

 

[S-Car-Go]

Yep, it's on the correct port. I guess Summit will get another $30 Thanks for the response.

 

[dennis112]

Yep, it's on the correct port. I guess Summit will get another $30 Thanks for the response.

I've been down this route too with the duraspark. Research showed that it is a very common problem. The adjustable vacuum advance (which I have) does very little to solve the real problem of too much travel. What you will need to do is to fabricate a stop of some kind to limit the total amount of advance. This is the route that I have taken.

Until that time, just leave the vacuum advance of and drive the car. You probably won't know the difference, except maybe a mile or two less gas mileage.