[Bruce Meyer]

Originally Posted by dpoltzer

Cranked engine over to TDC on compression stroke and the grove on dampner lined up perfectly at TDC with the timing cover scale at "0" degrees. I believe this tells us that the issue must be with the Vacuum advance unit in the distributor??

No. Vacuum advance does nothing when you accelerate. When you accelerate the vacuum drops off and the vacuum advance does nothing. I still think its your carb going lean. Typical of Q-jets

[dpoltzer]

Removed distributor from motor and then the old Vacuum Advance unit from the distributor. I noticed that the black wire that is screwed thru the rear of the VA unit and in to the distributor housing, has the end of the wire going to nowhere. Is this a ground wire and where does it get connected to? Dave

[johnta1]

Should be nothing there for wiring?


That looks like it could be off a condenser for the points?

[dpoltzer]

Condenser wire is connected properly to point set. Maybe this was present before I received car? I will not use this wire when I get this back together.

[dpoltzer]

I have driven the car several times before today and the motor and carb performed well with no stumble. I dont think the carb would have anything to do with the issue with the groove on the dampner moving by itself when I was NOT rotating the distributor. That is why I suspect the VA unit??

[Sun Tuned]

Dan that wire was originally crimped into a small tab that was then dpot welded to your breaker plate.

It was the breaker plate ground. It allows for the plate to be properly grounded to the distributor since the plate pivots on the top bushing.

[Bruce Meyer]

Originally Posted by Sun Tuned

Dan that wire was originally crimped into a small tab that was then dpot welded to your breaker plate.

It was the breaker plate ground. It allows for the plate to be properly grounded to the distributor since the plate pivots on the top bushing.

Sun Tuned. Have you ever heard of a vacuum advance causing a stumble off idle?

[Kenth]

You said vacuum advance was not connected when checking initial, so why do you suspect that it is faulty?

And the wire at the screw holding the vacuum advance is a ground wire and should be crimped on to the breaker plate.

[dpoltzer]

I replaced the vacuum advance unit and connected the ground wire to the breaker plate yet the stumble is still present. I then took the Rochester Q.jet off my 1969 T/A and put it on the 1974 and the motor runs great and with NO stumble. This confirms the stumble is being caused by the 7044262 carb which is what most here thought was the problem. I suppose I will try using the lean drop adjustment process tomorrow to see if that helps?

[steve25]

There ya go good old process of elimination never fails!

[Kenth]

Originally Posted by dpoltzer

I replaced the vacuum advance unit and connected the ground wire to the breaker plate yet the stumble is still present. I then took the Rochester Q.jet off my 1969 T/A and put it on the 1974 and the motor runs great and with NO stumble. This confirms the stumble is being caused by the 7044262 carb which is what most here thought was the problem. I suppose I will try using the lean drop adjustment process tomorrow to see if that helps?

See post #12 and do what is necessary. There is NO way around this.

FWIW

[dpoltzer]

Had the idle tubes changed out to the .038 tubes and the other changes made and now no more stumble. Thanks for all of the great advice to get this carb working correctly! All of your input is appreciated! Dave