Bouncing timing mark

[Fran Blacker]

I have the reluctor ring and pickup gapped at .008.

The object to check all 8 is to see if the shaft is tweaked.

 

[JG1966]

A little outside the box maybe. Any possibility your picking up spark scatter off another terminal/wire? Have you tried a different timing light?

Thanks Dave. That's the first thing I'm going to do tomorrow (I'm done for today) is check it again and make sure my timing light connector on wire No. 1 is free and clear of wire No. 3. I kind of doubt it's causing it, but I appreciate every suggestion.

 

[beanhead]

Thanks Dave. That's the first thing I'm going to do tomorrow (I'm done for today) is check it again and make sure my timing light connector on wire No. 1 is free and clear of wire No. 3. I kind of doubt it's causing it, but I appreciate every suggestion.

That's happened to me before...gave the timing light clip good separation and the flutter was gone...I hope that's all it is!

 

[Cranky]

The object to check all 8 is to see if the shaft is tweaked.

Checking 4 is sufficient unless a discrepancy is found and if there is, no need checking any the reluctor any further.....

And JG, what kind of timing light do you have?

 

[Fran Blacker]

Checking 4 is sufficient unless a discrepancy is found and if there is, no need checking any the reluctor any further.....

And JG, what kind of timing light do you have?

Yes I should have said every other one.

 

[JG1966]

Checking 4 is sufficient unless a discrepancy is found and if there is, no need checking any the reluctor any further.....

And JG, what kind of timing light do you have?

Thanks Cranky. I have an Innova 3555 dial back timing light. Barely three months old. I thought I might have a bad light but it works perfectly at idle. Only at higher RPMs do I have timing mark bounce. I pulled distributor, and shaft and bushings are fine, reluctor gaps are good. The blade drive at the end of distributor and cam drive "slot" all look good. I switched out the stock "medium" spring for a light spring, checked all plug wires at cap and plugs, I separated the wires a little bit more and put it back together. Something I did helped. Timing mark still bounces at higher rpm but not nearly as bad as before. Next job is borrow a dial back timing light I know works and then, if needed, check timing chain for excessive slack. But I think I just need a new distributor (and maybe new wires). Distributor is stock from 1972, so I'm probably due for a new one anyway.

 

[Shorthorse]

Also check your harmonic balancer. Sometimes the elastamor layer can separate/fail and cause issues like you are describing. Sometimes you can just move it by hand or you can put a socket on the crank bolt and turn it. If the outer piece does not move exactly with the inner piece, the balancer is bad.

 

[JG1966]

Also check your harmonic balancer. Sometimes the elastamor layer can separate/fail and cause issues like you are describing. Sometimes you can just move it by hand or you can put a socket on the crank bolt and turn it. If the outer piece does not move exactly with the inner piece, the balancer is bad.

Thanks Shorthorse. When I check timing chain, I'll double check harmonic balancer. I already tried to move it by hand and it wouldn't budge.

 

[Daves69]

I'll double check harmonic balancer

While your at it, you might verify TDC and mark both the inner ring and outer for quick visual of slip.

 

[JG1966]

I wanted to post an update and thank everyone who helped out. It was the spark plug wires. I put in a new set (fortunately before I took time to check timing chain (which I was fairly certain wasn't the culprit) and timing mark is rock solid at all RPMs. Thanks again.

 

[Fran Blacker]

dave69's got it. Check the simple stuff.

 

[Cornpatch MO]

A little outside the box maybe. Any possibility your picking up spark scatter off another terminal/wire? Have you tried a different timing light?

Bad timing light was what I was going to suggest..........................MO