I have recently got an 85 pickup with a 460 out of a 78 lincoln. It has a brand new edelbrock 750cfm (#1407) carb and a new distributor from napa. When I try to hook up the vaccum advance, the motor immediatly dies...... and yes I'm using the ported vaccum. So I took the distributor back and got a new one. Same thing... it doesn't matter what vaccum I hook to it, it instantly dies. If I try to start the truck up with the vaccum hooked up, it just coughs and sputters and won't run, so I assume it is getting full advance at an idle. My question I guess is, is my distributor bad (2 new ones in a row), or is something wrong with the carb? I have it running without vaccum on it and it runs good... just a little slugish as you can imagine. Any help would be greatly appreciated.

The Dura spark box could be bad. If so it will give iratic timing. but on the outher hand it sounds like your timing is to far advanced. if my memory serves me rigth it should be 8B tdc (but my memory is not to good somedays) But chiltons says to set by the data plate (as if we would buy there book to tell us that)

Start with checking your timing. Next see if the mech advance is working and how much timing advance it is putting in.. I think you'll find that your static timing is off,,,to far advanced. BTW, if your connencting the vac advance to the ported vac port on the carb, and the motor dies when you hook it up.....1: thats not the ported vac port, or 2: the throttle plates are open enough to casue a vac signal at the ported port..
Do you have a vac gaude? or better a guage/pump?

See if the ported port has a vac signal at idel (throttle plates closed) if it does your carb is not right. Second, using the vac pump, engine running, applie some vac to the dist advance, see if it dies right away, or at what level of vac signal imput.

You were saying that as soon as vac signal is applied to the dist vac advance the motor dies...right?

Originally posted by bronco78
Start with checking your timing. Next see if the mech advance is working and how much timing advance it is putting in.. I think you'll find that your static timing is off,,,to far advanced. BTW, if your connencting the vac advance to the ported vac port on the carb, and the motor dies when you hook it up.....1: thats not the ported vac port, or 2: the throttle plates are open enough to casue a vac signal at the ported port..
Do you have a vac gaude? or better a guage/pump?

See if the ported port has a vac signal at idel (throttle plates closed) if it does your carb is not right. Second, using the vac pump, engine running, applie some vac to the dist advance, see if it dies right away, or at what level of vac signal imput.

You were saying that as soon as vac signal is applied to the dist vac advance the motor dies...right?

Thanx for the great info. I have about 8 degrees of initial timing, so I don't think that it is too far advanced. I can take the distributor out and see that the mechanical advance does work. Yes, it dies as soon as I put the vaccum hose on the advance. I guess one thing I didn't think of is that there is a space (adapter) under the carb and maybe it isn't right...i.e maybe it is holding the throttle plate open a little bit, therefore giving it vaccum at an idle. Should there be absolutely no vac. at an idle for this distributor?

Thanx for the help