Timing Chain, Balancer, What else could this be???? - JeepForum.com
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post #1 of 32 Old 08-03-2020, 02:34 PM Thread Starter
ccoyle71
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Timing Chain, Balancer, What else could this be????

Prior to the recent upgrades I've done....I could barely get the Jeep to idle with the vac advance disconnected, so I really have no idea where the timing was actually set....since my Jeep ran so poorly. Using the "chopstick method", and confirming TDC of the compression stroke with the mark at 0 degrees....I installed my new distributor and made sure the new rotor was pointed at the exact same spot as the old one. It worked great. With a few minor tweaks to the new carb and an ever so slight timing adjustment rotating the distributor, I'm definitely in the "sweet spot". The Jeep runs amazing - better than it ever has. I repainted the "slot" on the balancer....and made a small white mark at 8 degrees.....But I'm baffled by the variance. I'm hoping you can see in this video below. Is it even possible that it could be this far off?? Literally 16 degree swings at times......all the while, not even a hint of a stumble while idling.



I've been researching a timing chain replacement this fall......but I'm curious to get everyone's thoughts. If it was really "jumping" time like the mark would suggest......wouldn't I have a poor running Jeep? Or at least some mis-firing and stumbling? I hear no "clacking" of the chain, no misses, and from a performance standpoint.....it seems as close to perfect as it has been since I owned it. Any other thoughts? Can the balancer pulley slip on the crankshaft?? I'm scratching my head over here. Any input is much appreciated.





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post #2 of 32 Old 08-03-2020, 02:49 PM
John Strenk
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Could be the vacuum advance plate in the distributor is loose.


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post #3 of 32 Old 08-03-2020, 02:54 PM Thread Starter
ccoyle71
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Quote:
Originally Posted by John Strenk View Post
Could be the vacuum advance plate in the distributor is loose.

Wouldn't that actually affect how it runs? It is a brand new distributor, but I can check that.....
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post #4 of 32 Old 08-03-2020, 03:23 PM
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Quote:
Originally Posted by ccoyle71 View Post
Prior to the recent upgrades I've done....I could barely get the Jeep to idle with the vac advance disconnected, so I really have no idea where the timing was actually set....since my Jeep ran so poorly. Using the "chopstick method", and confirming TDC of the compression stroke with the mark at 0 degrees....I installed my new distributor and made sure the new rotor was pointed at the exact same spot as the old one. It worked great. With a few minor tweaks to the new carb and an ever so slight timing adjustment rotating the distributor, I'm definitely in the "sweet spot". The Jeep runs amazing - better than it ever has. I repainted the "slot" on the balancer....and made a small white mark at 8 degrees.....But I'm baffled by the variance. I'm hoping you can see in this video below. Is it even possible that it could be this far off?? Literally 16 degree swings at times......all the while, not even a hint of a stumble while idling.



I've been researching a timing chain replacement this fall......but I'm curious to get everyone's thoughts. If it was really "jumping" time like the mark would suggest......wouldn't I have a poor running Jeep? Or at least some mis-firing and stumbling? I hear no "clacking" of the chain, no misses, and from a performance standpoint.....it seems as close to perfect as it has been since I owned it. Any other thoughts? Can the balancer pulley slip on the crankshaft?? I'm scratching my head over here. Any input is much appreciated.
It seems like you found the timing mark on the balancer aligning with the scale marks on the timing cover. So, I can assume your balancer did not "slip". Then you found the "average" or the "Sweet Spot" for the timing which is all you can do with this much timing mark variations.

I have never seen timing marks vary this much, as you claim 16 degrees variance, so yes it is bouncing the timing this much. Do you have any idea about this jumping timing before the HEI upgrade? Like John said it "could be" the advance plate came loose in the distributor.

This looks like timing chain and sprockets are in your future to me.

$0.02 worth
UTN
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post #5 of 32 Old 08-03-2020, 03:28 PM
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You could mark the face of the harmonic balancer (inner piece marked to outer piece) to see if there is slipping.

Temporarily remove the belt and check the timing again.

The vacuum advance hose is removed from the distributor and PLUGGED OFF? (no vac leak)

Try a different gun?

Is the pickup from the gun on "1" and away from the other spark plugs wires?

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post #6 of 32 Old 08-03-2020, 03:31 PM
John Strenk
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A simple test would be to move the crank back and forth and see how much the crank moves before the distributor moves.
This is just a rough test though. You need to take the timing cover off and visually inspect the chains.

Whats your vacuum level on the vacuum advance look like is it fluctuating?
Another simple test, pinch off the vacuum advance line...
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post #7 of 32 Old 08-03-2020, 03:53 PM Thread Starter
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Quote:
Originally Posted by uptillnow View Post
Do you have any idea about this jumping timing before the HEI upgrade? This looks like timing chain and sprockets are in your future to me.UTN
Don't really know where the marks were before, but it would barely idle long enough to check it with the vacuum disconnected and capped. I agree on the chain / sprockets - just wanted to get the expert opinions here to make sure I'm not missing anything obvious. Thanks UTN


Quote:
Originally Posted by John Strenk View Post
A simple test would be to move the crank back and forth and see how much the crank moves before the distributor moves. Whats your vacuum level on the vacuum advance look like is it fluctuating? Another simple test, pinch off the vacuum advance line...

Will check these - as well as the plate in the distributor and report back. I'll check vacuum level again, but IIRC it was 21 or so and smooth after the carb and HEI install. To check it, I tee'd into the manifold source that is running to the distributor.....and it seemed good / normal from what I've read. Thanks John



Quote:
Originally Posted by JEEPFELLER View Post
You could mark the face of the harmonic balancer (inner piece marked to outer piece) to see if there is slipping. Temporarily remove the belt and check the timing again. The vacuum advance hose is removed from the distributor and PLUGGED OFF? (no vac leak) Try a different gun? Is the pickup from the gun on "1" and away from the other spark plugs wires?----JEEPFELLER


Will try these as well. Yes, vac hose was removed and capped. The gun is mostly new, but I'll try to borrow one to confirm i didn't get a "bad" timing light. And yes - pickup was attached to #1 wire and away from other wires. Thanks JF



I do appreciate all the advice, I'll check the things above tonight and report back.
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post #8 of 32 Old 08-03-2020, 04:46 PM
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Before i started taking things apart i would check the timing light on another vehicle or if you can get your hands on another light and see if you get the same results to rule out a timing light malfunction. Thing is, with a worn timing chain, it really shouldn't fluctuate that much. A few degrees here and there ok, but 16 is a lot. It sounds like more of a distributor issue but you said it was new. I would check the power connections to the Dis. and make sure they are making good contact. If you hook up the vacuum advance does the mark on your balancer still fluctuate that much?
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post #9 of 32 Old 08-04-2020, 05:40 PM Thread Starter
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Here’s another video taken just now. Advance disconnected and capped, and a gauge hooked up. Gauge reads right around 20-21....and what I would call steady....but you guys tell me??? Seems okay, right? Idling smooth.....and again, running fine.....but alas - timing marks all over the place. Im currently waiting on a friend to come by with his light now so I can re-check....and will keep you guys posted. #imconfused




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post #10 of 32 Old 08-04-2020, 08:39 PM
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That first video of the timing bouncing around is caused by the mechanical advance, not working correctly. Put the timing light on it again and advance the throttle slowly and I bet is stops bouncing around, and steadies out. As you raise the RPM’s most distributors will max out the mechanical timing around 2000 RPM. There are a couple weights that are held in against centrifugal force by springs. When the RPM’s rise the weights overcome the springs, and swing out advancing the timing, by rotating the rotor shaft. Yours is missing a spring or weight, and can’t hold the weights steady against the centrifugal force. Take the cap off and you should be able to rotate the cap one direction, and when you let go the springs should snap it back. Take the rotor off and you can view the entire system. Something is not right with your mechanical advance on that distributor.

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post #11 of 32 Old 08-04-2020, 08:58 PM
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HI the timing bouncing around like that is a classic sign of a bad timing chain.. replace the chain and gears.. I've never heard of the advance plate causing that and its a new distributor.. Timing chain.. Some of the old gears had a resin or plastic gear over the steal gear and they would break causing what you are seeing..
good luck
tim
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post #12 of 32 Old 08-05-2020, 06:35 AM
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Timing chain slop is an easy one to check, as mentioned earlier. Just turn the crank manually back and forth, while watching the rotor. If the crank rotates more than a few degrees before the the rotor moves, the chain has too much slop.

I doubt it's a problem with the mechanical advance. If you had a missing or broke advance spring, the timing would jump up high and stay there, not bounce around.

Do the chain slop test and let us know what you find.

Matt


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post #13 of 32 Old 08-05-2020, 09:19 AM Thread Starter
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Figured it out. And I'm embarrassed to report back.....but thought it may help another idiot out there like me.
When my friend came over with his timing light last night and we checked, the mark was dead on....and very steady, at about 10 degrees. I'm sending my light back today......as I have now learned......are you ready for it???? MY LIGHT IS STUCK ON THE RPM FUNCTION!.....and won't switch over the the ADV setting.....where it correctly reads the pickup as #1 fires! So.....the whole time, my timing has been okay (or close to okay).....and my light (that is basically brand new)....is foo-barred. Geez.....don't I feel stupid - probably should have noticed that, and like I said, I'm embarrassed to report back to you guys. I understand that this may have me forever banned on the forum, but wanted to let you guys know all is well - and I have a new light on the way. Just for any newbs like me.....in the photo below of my timing light.....mine is "stuck" on the red circle.....and you can't switch it to the green circle. From what I've now read in the instructions......pressing the rpm/adv button should toggle between the two - and it won't flash correctly if the RPM setting is selected. DUH, right?? Let the roast begin - and thanks again for all the advice on this and other topics!
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post #14 of 32 Old 08-05-2020, 09:45 AM
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If you haven't had something silly like that happen, you've simply never turned a wrench. I'm glad you got it spotted before you yanked the front of the engine off, though. You'd really be kicking yourself in the arse.


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post #15 of 32 Old 08-05-2020, 10:06 AM
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