Guys, I'm having trouble with my brother's Nova. 307/HEIw/Vac Advance.

I've got some Q's.

At idle, if you were to advance the dist. timing enough, would the idle RPM eventually lower again?

Under what conditions would removing the vacuum source from the vacuum advance lead to a faster Idle than when its hooked up?

Here's what we know:

1. We can plug all vac ports on the carb(except PCV, engine dies with PCV port open), then remove any of the plugs (leaving the port open) and the Idle RPM won't change.

2. If vac adv is hooked up, Idle is lower. Unhooked from dist or carb, idle up.

3.Turn dis CCW, Idle RPM will go down. CW, firt it goes up and then at one point it'll begin going down again.

4. We move all the spark plug wires one position CCW and the engine ran, but you could not move the dist CCW because it would die. CW, and it advanced.

5. Moved the plug wires one position CW from original position, and the carb would spray out the top if we tried to turn on the engine.

6. Tried 65721843 (6 at the #1 tower, etc, 180-out check), didn't fire, carb spray again.)

7. Replaced vac adv can with one that doesn't work. It stopped doing #2, but still advanced CW, etc. (as described in #3.

8. Replaced the condensor and attatched wiring, no effect.

Any Ideas?

Originally posted by Slowpoke70:
Guys, I'm having trouble with my brother's Nova. 307/HEIw/Vac Advance.

I've got some Q's.

At idle, if you were to advance the dist. timing enough, would the idle RPM eventually lower again? Yes. It would require quite a bit of advance though.

Originally posted by Slowpoke70:
Under what conditions would removing the vacuum source from the vacuum advance lead to a faster Idle than when its hooked up? A) If you had way to much vacuum advance, or your base timing + vacuum advance timing was too much.

B) by removing the vacuum advance line and leaving the vacuum source open creating a vacuum leak. Best way to tell is to disconnect the hose AFTER pinching it closed with a pair of vice grips. If it still goes up, then it's because you have too much advance. If it doesn't, then it is because of the "vacuum leak" that you were creating.

Mike