My timing mark is jumping around.

Jeff Skibenes

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My timing mark is jumping all around +/- 25 degrees. I just replaced the points/condenser, rotor, wires and plugs. I'm guessing I should pull the distributor? 1966 Chrysler Newport 383 2bbl.
 
Is the motor running rough? I would look at the harmonic balancer. If the rubber is old the outer ring could be moving and throwing off the mark.
 
When my 318 marks were bouncing around I pulled the timing cover to find 3 teeth missing and enough slack in the chain I could almost pull the chain off by hand.
 
That sounds more like a timing light problem. If your timing was really jumping around that much it probably wouldn't run.

First, assuming you have a clamp on type light, try moving the clamp to a different location on the wire. If that doesn't help, try a different light.
 
That sounds more like a timing light problem. If your timing was really jumping around that much it probably wouldn't run.

First, assuming you have a clamp on type light, try moving the clamp to a different location on the wire. If that doesn't help, try a different light.
Copy that. Thanks. I have never seen this kind of jumping around ever in my life. A degree or three maybe, but no more than that
 
The car has 64000 orig. miles. Could the chain be in that condition already?

Are you sure that it's only 64K and not 164K? Or are you just believing what's been told to you?
Remember: A wise man is never sure, but a fool is always positive! Good Luck
 
Pull your distributor cap. Next align the timing mark to TDC. Have a helper rock the crank back and forth with a socket and breaker bar attached. Note how many degrees it takes to get the rotor to move, anything 15 degrees or more and the timing chain is at the point of failure. Yes the plastic faced gears can fail at 64k, they are now 50 years or so old and very brittle.

Dave
 
Catastrophe averted! Apparently the timing light pick up was getting thrown off by the #3 and #5 wires running right next to where I had the pick up installed. Well, its been at least 35 years since I have set timing like this, so I guess I am a little rusty. I want to thank you all for your input. Dave, I am still going to sheck the chain as you have suggested to find out what kind of slack is showing up. Timing chain replacement is relatively easy before the jump occurs, but kinda sucks after! Again thanks to all your constructive advice!
 
Oh yeah, and I took the car for a ride, and it runs better than it has since I got it. And the fuel gauge which has not worked since I got it suddenly decided to come back to life! Today is not a bad day.
 
When the cars were newer, about 80K miles and the "borrowed time" syndrome started to happen, by observation, especially on some GM engines. At this point in time, on your car, it's more about "time" than "miles".

Now that you've got things going pretty well, get a name brand (i.e., Cloyes) timing set and put at least a new chain and cam sproket in it soon. Going to a roller chain will be a "once-in-a-lifetime" deal as they'll last that long with no issues, from my experiences. A roller chain is CHEAP long-term insurance in basic engine longevity. Douse the new timing chain parts in oil before putting the front cover back on, for good measure.

In using an inductive timing light pickup, find the place on #1 wire where it's the most isolated from the other wires, for best results. As an alternative, you can also use #6 as it's the first cyl in the 2nd half of the firing order.

Enjoy!
CBODY67
 
Used to be common as hell with a Pontiac V8. 70k and the timing chain went.
 
Double roller timing chains make ++good insurance for your engine. I changed my old one for a double roller 17 months ago, and it stopped what little slop the old one caused.
 
When the cars were newer, about 80K miles and the "borrowed time" syndrome started to happen, by observation, especially on some GM engines. At this point in time, on your car, it's more about "time" than "miles".

Now that you've got things going pretty well, get a name brand (i.e., Cloyes) timing set and put at least a new chain and cam sproket in it soon. Going to a roller chain will be a "once-in-a-lifetime" deal as they'll last that long with no issues, from my experiences. A roller chain is CHEAP long-term insurance in basic engine longevity. Douse the new timing chain parts in oil before putting the front cover back on, for good measure.

In using an inductive timing light pickup, find the place on #1 wire where it's the most isolated from the other wires, for best results. As an alternative, you can also use #6 as it's the first cyl in the 2nd half of the firing order.

Enjoy!
CBODY67
Thank again for all the advice! It is very much appreciated and I will replace the timing chain this year.
 
Make sure the distributor is making a good ground. If it is the gasket type seal instead of a o ring you should use a metal gasket. Thats exactly what happens on the distributor machine when one has a bad case ground. Also can be point float or a condenser on its way out also.
 
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