Timing moving

[crisrenn]

71 Stock 302. Jumped out of time, I thought. I was able to turn the distributor and get it back. Moved out again. Decided it needed timing chain. Got the timing cover off, didn't look to be out of time. Decided it must have jumped back. Did the timing chain and gear replacement. Ran great. Then out of time again. Readjusted the distributer. Ran great. Moved out of time again. Pulled the distributer again. Inspected the cam gear all the way around twice, and the distributer gear. Look fine. No unusual wear, no missing teeth. Distributer gear appears to still be pinned solid to the distributer shaft. I only tested that by hand. No vice or pliers. Shaft is solid as far as I can tell. Again just by hand twisting.
What in the wide world of sports is going on?

%)

 

[SteveL]

When I had that going on it was the cam.

 

[SHX669]

Does your rotor fit tight against the distributor shaft ?
Is your "lock down " screw and bracket tight and holding the distributor securely in place so it can't turn?

 

[77broncodriver]

I had a similar issue where I would check the timing and it would be off. Turns out the keyway of my balancer had became 4 times the width of the key so the timing marks were in different locations every time I would check the timing.

 

[Crush]

Mine did that and the dizzy gear pin had sheareed off but it was still tight. Could not turn it by hand or with a little force. How i discovered it is the gear pin was 90* from the shaft pin. In other words if you could look at them from above they would make a plus sign. I check a bunch of other dizzies i had laying around and the pins were oriented the same direction. So i forced the gear off the shaft and sure enough the pin was broken and the gear 90* off. Drove out the old pin and reinstalled the gear. No problems since

 

[crisrenn]

As in what with the cam?

 

[crisrenn]

Does your rotor fit tight against the distributor shaft ?
Is your "lock down " screw and bracket tight and holding the distributor securely in place so it can't turn?

Yes, the dist is not turning on it's own.

 

[crisrenn]

I had a similar issue where I would check the timing and it would be off. Turns out the keyway of my balancer had became 4 times the width of the key so the timing marks were in different locations every time I would check the timing.

I just replaced the timing gears, the key way was fine.

 

[crisrenn]

Mine did that and the dizzy gear pin had sheareed off but it was still tight. Could not turn it by hand or with a little force. How i discovered it is the gear pin was 90* from the shaft pin. In other words if you could look at them from above they would make a plus sign. I check a bunch of other dizzies i had laying around and the pins were oriented the same direction. So i forced the gear off the shaft and sure enough the pin was broken and the gear 90* off. Drove out the old pin and reinstalled the gear. No problems since

The pins were in the same orientation. I can double check that though to see if it holds up with more pressure applied.

 

[crisrenn]

This thing gets out of time enough that I have to pull and reposition the distributer to get it back.

 

[SHX669]

This thing gets out of time enough that I have to pull and reposition the distributer to get it back.

Generally when that happens the timing chain has jumped a tooth or two but since you replaced that - hmm .
On a side note ; if you pull the distributor and " reposition " it you'll change the ignition timing in relation to the valve timing = burnt valve/valves.

 

[SteveL]

As in what with the cam?

I believe the cam wore down where the dizzy gear rides. It was a week before my wedding(22 years ago) so I had a shop deal with it. Wish I'd have done it myself. For what they charged I could've built and installed a new motor.

 

[DirtDonk]

this is still the original points type distributor presumably?

And can you inspect the condition of the damper ring on the crank damper, to make sure it is not slipping. I'm thinking this is NOT the issue, but didn't see it mentioned and thought it would be good to know.

But since you've changed the timing so very often already and it still seems to be running properly(?) it really should not be any of the usual suspects mentioned.
If the cam and crank timing were moving so much, it would run like crap even when ignition timing is good.
If the crank and ignition timing were moving so much due to most circumstances, it would run like crap too.
If you have to move it so far you have to pull the distributor to skip a tooth, that's a LOT of variation!

How has it been running in all this, and have you known the timing was off each time because it starts to run like crap until you get the marks lined back up?

I've certainly seen plenty of inconsistent timing issues, but never one that was so consistently far off you have to move the distributor gear position multiple times.

Good luck!

Paul

 

[crisrenn]

this is still the original points type distributor presumably?

And can you inspect the condition of the damper ring on the crank damper, to make sure it is not slipping. I'm thinking this is NOT the issue, but didn't see it mentioned and thought it would be good to know.

But since you've changed the timing so very often already and it still seems to be running properly(?) it really should not be any of the usual suspects mentioned.
If the cam and crank timing were moving so much, it would run like crap even when ignition timing is good.
If the crank and ignition timing were moving so much due to most circumstances, it would run like crap too.
If you have to move it so far you have to pull the distributor to skip a tooth, that's a LOT of variation!

How has it been running in all this, and have you known the timing was off each time because it starts to run like crap until you get the marks lined back up?

I've certainly seen plenty of inconsistent timing issues, but never one that was so consistently far off you have to move the distributor gear position multiple times.

Good luck!

Paul

Yes, Points are still in it. Yes, after repositioning the distributor & resetting the timing it runs fine. Then it somehow ends up running like crap, what ive been doing is just adjusting the distributor until it runs good again without setting the timing with a light. I finally, just today, swapped out the distributor. I set the timing at 6 btdc and it stuttered and farted a lot. I now have it set at about 2 ATDC. It runs well but will giva a backfire when I shut it off. I did think about the balancer rubber perhaps letting the outer ring move on the crank pulley but that would only show the timing off on the pointer, it wouldn't move the timing. I'm going to leave it as is for a while and see if it moves out of time with this different distributor.

I appreciate everyone's input!

 

[crisrenn]

I believe the cam wore down where the dizzy gear rides. It was a week before my wedding(22 years ago) so I had a shop deal with it. Wish I'd have done it myself. For what they charged I could've built and installed a new motor.

The cam gear looks good. I had a buddy manually turn the crank while I peeped down the dist. hole.

 

[crisrenn]

Generally when that happens the timing chain has jumped a tooth or two but since you replaced that - hmm .
On a side note ; if you pull the distributor and " reposition " it you'll change the ignition timing in relation to the valve timing = burnt valve/valves.

When I pull the dist. I'm positioning the motor back at tdc beforehand.

 

[jckkys]

How's the new distributor working? I was going to suggest checking the centrifugal advance, to see if it's binding or if the one of the springs is broken.

 

[crisrenn]

Mine did that and the dizzy gear pin had sheareed off but it was still tight. Could not turn it by hand or with a little force. How i discovered it is the gear pin was 90* from the shaft pin. In other words if you could look at them from above they would make a plus sign. I check a bunch of other dizzies i had laying around and the pins were oriented the same direction. So i forced the gear off the shaft and sure enough the pin was broken and the gear 90* off. Drove out the old pin and reinstalled the gear. No problems since

I positioned the dist upside down in a vice with the vice loosely suspending it under the gear and gave the shaft about 6 good raps with a hammer on a block of wood. Nothing moved. I guess I'll see if I can drive the pin out. & and the pin drove out all in one piece...

 

[B RON CO]

Hi, is it possible the rotor is not keyed properly and is spinning on the distributor shaft? Or the distributor shaft is split in the housing.
I have read this post a couple of times and the moving rotor is all I can think of.
Everything is linked together by gears and chains and steel pins.
That is my wild guess.
Good luck

 

[SHX669]

Just throwing a few things out there ; does the rotor fit tight and have the proper shoulder to notch fit to prevent it from turning on the distributor shaft .
Which cylinder are you using as #1 - { passenger side closet to the radiator} ?
Does your distributor have one OR two vacuum connections ?
Where do you have these vacuum lines connected ?