C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Timing won't stay set. Distributor moving?

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Old Sep 16, 2007 | 12:19 PM
  #1  
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Default Timing won't stay set. Distributor moving?

I've been checking my timing every couple months and I'm noticing that it keeps reverting to 0* advance. Not sure what's going on, but it's the third time this has happened over the past year.

- I'm making sure to check it with the timing wire disconnected.
- The engine is at normal operating temps (coolant/oil both over 150).
- The timing marks on the balancer are NOT slipping - I have a ~2 year old FluiDamper which is all one piece so the marks can't move.
- I have a non-stock distributor (Davis Unified Ignition)

Near as I can tell, the distributor is turning a little, but it always stops at the same place. I'm tightening the hold-down bolt as much as I can, but I'm afraid of breaking it so I'm not *REALLY* hanging on it. Also, it's not easy to figure the torque spec when tightening because of its location and the fact that I need to use an offset wrench to reach it.

This time, I marked the distributor and the plenum to see if it actually is moving; if that is the problem, anyone have suggestions on how to convince it to stay put?

Thanks.
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Old Sep 16, 2007 | 12:29 PM
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I have never seen a distributor that was bolted down slip. Are you sure you don't have something very funky going on between your cam gear and distributor gear? I ran a bronze distributor gear for a short time. Couldn't keep the beast in time. Pulled the distributor,bronze gear was almost gone, worn so bad.
Old Sep 16, 2007 | 12:34 PM
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Replace the bolt with a stud, and smear a little valve grinding compound on the bottom of the clamp, where it contacts the distributor.
Old Sep 16, 2007 | 01:31 PM
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Hm. I honestly don't remember what material the distributor gear is made form. The cam has whatever Lingenfelter provides; I'd hope it's not bronze since they make high-performance/high stress items...

Pete, nice thought on the stud. I'll have to try that.

Car runs SOO much better when it's in time :/ .

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Old Sep 18, 2007 | 12:47 AM
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I have a stupid question. Have you ever removed the distributor hold down bolt ? After a manifold gasket replacement I put the hold down clamp on upside down and the distrb. would not stay tight and would slip. Once I fliped the clamp I added a washer and it doesn't slip anymore. Just a thought.
Old Sep 18, 2007 | 05:27 PM
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Interesting thought; it's not a stock distributor and I *thought* I put the hold-down on right. I'll look at it again.
Thanks.
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Old Sep 18, 2007 | 07:02 PM
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Sounds like the Balancer - Find TDC and see if the mark is still in alignment.
Old Sep 18, 2007 | 11:15 PM
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No offense, but I stated initially that the timing marks can't move - the balancer is a single piece Fluidamper, not the GM rubber-mounted ring. Also, the car WAS out of timing. It runs a heck of a lot better now.
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Old Sep 19, 2007 | 01:25 AM
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There is another possability....your distributor hold down bolt may be bottomed out. That happend to me and I'll be damned if I wanted to pull the bolt out and cut it off and fight to get it back in. Instead, I cut out a small section in a lock washer, backed out the bolt a little and slipped the washer around the bolt between the head and the distributor hold down piece. This gave me the additional clearance to tighten the bolt without bottoming out. The distributor does not move any more.
Old Nov 25, 2019 | 04:40 AM
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Originally Posted by rrubel
I've been checking my timing every couple months and I'm noticing that it keeps reverting to 0* advance. Not sure what's going on, but it's the third time this has happened over the past year.
- I'm making sure to check it with the timing wire disconnected.
- The engine is at normal operating temps (coolant/oil both over 150).
- The timing marks on the balancer are NOT slipping - I have a ~2 year old FluiDamper which is all one piece so the marks can't move.
- I have a non-stock distributor (Davis Unified Ignition)
Packing and moving companies near me url g&j moving.
Near as I can tell, the distributor is turning a little, but it always stops at the same place. I'm tightening the hold-down bolt as much as I can, but I'm afraid of breaking it so I'm not *REALLY* hanging on it. Also, it's not easy to figure the torque spec when tightening because of its location and the fact that I need to use an offset wrench to reach it.

This time, I marked the distributor and the plenum to see if it actually is moving; if that is the problem, anyone have suggestions on how to convince it to stay put?

Thanks.
[RICHR]

how did you solve your question?
Old Nov 25, 2019 | 05:52 AM
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I'm sorry; this was 12 years ago and I just don't recall now.
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Old Nov 25, 2019 | 11:32 AM
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Originally Posted by rrubel
I'm sorry; this was 12 years ago and I just don't recall now.
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Lol
Old Nov 25, 2019 | 11:56 AM
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Originally Posted by Chippos
how did you solve your question?
12 year old thread... It could quite possibly have been the bolt bottoming out?

Something I didn't see in this thread that should be mentioned (if someone is searching these issues), is shimming the distributor shaft for end play. They sell kits for it, and basically if its loose the distributor gear can walk up and down the cam gear affecting the timing slightly.


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