ZZ4 run-on...
Thread Starter
Instructor
Joined: Jun 2006
Posts: 223
Likes: 0
From: Merritt Island FL
ZZ4 run-on...
Hello all,
I have a 1967 with a ZZ4 crate engine. I'm having a run-on (dieseling) problem. I was wondering if any of you had any ideas of how to stop it.
Here's what I have installed:
ZZ4 350ci GMPP crate engine
Demon carb (crate engine model)
MSD 6AL ignition box
MSD Pro Billet Distributor (tach-drive)
MSD Baster 2 coil
Stock GM (2 wire) distributor
Stock(ish) ignition relay box
I've installed the little capacitor supplied with the 6AL box. I went back and double checked that it was installed correctly (soldered in-line on the green wire (4th pin on the ignition box), and that the line on the cap was closer to the plug going to the alternator). ... This didn't solve the problem.
My timing is set to dead-nutz "0"... should I advance it and see if that helps?
The carb is running a little rich, but all the floats seem to be set properly and the car runs fine....
Any help or suggestions would be great.
I have a 1967 with a ZZ4 crate engine. I'm having a run-on (dieseling) problem. I was wondering if any of you had any ideas of how to stop it.
Here's what I have installed:
ZZ4 350ci GMPP crate engine
Demon carb (crate engine model)
MSD 6AL ignition box
MSD Pro Billet Distributor (tach-drive)
MSD Baster 2 coil
Stock GM (2 wire) distributor
Stock(ish) ignition relay box
I've installed the little capacitor supplied with the 6AL box. I went back and double checked that it was installed correctly (soldered in-line on the green wire (4th pin on the ignition box), and that the line on the cap was closer to the plug going to the alternator). ... This didn't solve the problem.
My timing is set to dead-nutz "0"... should I advance it and see if that helps?
The carb is running a little rich, but all the floats seem to be set properly and the car runs fine....
Any help or suggestions would be great.
Thread Starter
Instructor
Joined: Jun 2006
Posts: 223
Likes: 0
From: Merritt Island FL
Thread Starter
Instructor
Joined: Jun 2006
Posts: 223
Likes: 0
From: Merritt Island FL
Racer
Joined: Jun 2009
Posts: 326
Likes: 0
From: Texarkana TX
double check tdc on the balancer...the outer ring can slip and cause some major headaches...also try a dial back to zero timing light...set on 32deg total advance...remove vacuum advance hose bring engine up to full advance (typically 3500rpm) and line up timing marks...good luck!
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Thread Starter
Instructor
Joined: Jun 2006
Posts: 223
Likes: 0
From: Merritt Island FL
Checked the timing and it was 3deg retarded. :o
So, I went in steps, upping the timing until maximum vacuum was gained (about 15 inches at idle). Ended up with just a little over 9deg of advanced timing. Runs fine now (quite a bit more power too! 
)
So, I went in steps, upping the timing until maximum vacuum was gained (about 15 inches at idle). Ended up with just a little over 9deg of advanced timing. Runs fine now (quite a bit more power too! )
Racer
Joined: Jul 2007
Posts: 317
Likes: 0
From: Crab Orchard Tennessee
