Timing mark jumps around at idle

[cdn66satellite]

Motor runs great in the car but when you put a timing light on the damper it jumps around between 18-24 ish degrees. Idles nice and smooth. Brand new everything in the motor. Anyone else experience this before? Thank you

 

[747mopar]

Start with checking the distributor intetnals for slop, loose springs, etc.

 

[cdn66satellite]

Start with checking the distributor intetnals for slop, loose springs, etc.

Will do. Thank you

 

[440+6]

My old Mopar Performance distributor was doing the same thing, even at higher RPM's. I installed a fire core distributor from Mancini racing and its rock solid at any given rpm.

 

[69Bee]

Sloppy distributor bushings for sure.

 

[CoronetDarter]

Distributor is #1 place to look. Did you replace the harmonic balancer when you did the motor?

 

[eagleone1983]

I've got the same issue but never looked into because the motor besides that is flawless. My distributor was one from FBO

 

[cdn66satellite]

I've got the same issue but never looked into because the motor besides that is flawless. My distributor was one from FBO

yeah brand new balancer on there too. This motor runs great too, however, I've got a nitrous kit on it and if i have to retard some timing, would be nice to know if im retarding it from 18 degrees or 24 degrees haha

 

[eagleone1983]

I didn't replace my balancer but checked mine out and it was good. when I timed my car I just went off vacuum and sound.

 

[zyzzyx]

I would be wondering about how sloppy the timing chain was? any "play" in the valve train will show up in the distributor, which is the "Caboose" in the system. Make sure your distributor
drive gear that also drives the oil pump is not moving up and down, and that the bushings are not worn. This part is called an "Intermediate Shaft". Good luck!

 

[eric383]

Some types of electronic ignition systems can cause this because of the multi spark firing.

 

[dieseldazzle]

If you have multiple spark discharge box often they need a timing light that is compatible with them.

Otherwise slop in dizzy or timing set or even balancer ring not in good shape.....the years do go by.....

 

[2Shea]

As DieselDazzle says. I worked on a mustang a while back that had an MSD and the marks weren't steady with my digital dial back light. I switched to the analog dial back light and it was rock steady.

Just something to check. ....John

 

[cdn66satellite]

Finally got around to checking things out. The vacuum line from the carb to the vac advance wasn't proper vacuum so was messing with the advance but cant seem to get good vacuum from this eddy carb. Switching to a holley and see how this goes.

 

[lewtot184]

Finally got around to checking things out. The vacuum line from the carb to the vac advance wasn't proper vacuum so was messing with the advance but cant seem to get good vacuum from this eddy carb. Switching to a holley and see how this goes.

the timed port on the edelbrock is different than the holley. it sits right at the throttle blade. this will bring the timed port into manifold vacuum when the throttle blade lifts. the holley has the port in the venturi well above the throttle blade and the vacuum signal is more gradual. i doubt the carb has anything to do with timing fluctuations; unless it is poorly tuned and causing an erratic idle.

 

[coloradodave]

I'll just add that vacuum isn't produced by the carburetor, so whether it's an Edelbrock or a Holley, adjusted correctly, the vacuum will be the same.