Are United Motor Products distributors adjustable for Cam Retard?

[Dean89]

I put the UMP distributor in the link below in a brand new GM Crate motor about a year ago in my 99 tahoe. The engine ran flawlessly for 10k miles, but suddenly started having hesitation, stumbling issues. With an old MT2500 scanner I checked the Cam Retard and it was reading -12 degrees. I loosened the distributor hold down bolt, but could not rotate the distributor. It appears to me that this distributor can not be rotated as where the hold down clamp attaches to the distributor it is not round and free to rotate. I ordered a GM distributor hold down clamp, but not sure if that will make a difference. Should I order a GM remanufactured distributor instead of trying the UMP product? I'm guessing my problem is the cap and rotor already. I was surprised to see the condition of the cap that has only 10k miles on it. I ordered a UMP DCR820X, hoping it is a better cap and rotor.
Thanks!

More Information for UNITED MOTOR PRODUCTS 9362

 

[454cid]

Spec is +/-2, but I don't think it sets a code until the low 20's. I was running around with a 7 for awhile, and noticed no difference when re-set. While I understand you probably want to get closer than -12, I'd look elsewhere for the hesitation. You said the cap looks bad. They're brass contacts aren't they? Maybe try cleaning them? If that doesn't work, I'd suspect an internal short, which is the hallmark of a cheap cap. Hopefully, the standalone caps are better than that. It could be the caps that come with the distributor aren't the same as the ones they sell by themselves.

Some of the distributors are not adjustable.... V6s' I believe are not. I do not know if the GM hold down will help. I still have my original, and a Delphi in reserve.

 

[1998_K1500_Sub]

I'm guessing my problem is the cap and rotor already.

If the distributor isn't aligned properly for the cam retard, the spark internal to the cap may have a longer jump between the rotor tip and the corresponding electrode on the cap; this of course varies with ignition timing. This situation gets increasingly worse with increased "cam retard" mis-adjustment until it become so bad that the tip of the rotor is closer to the wrong electrode, leading to a mis-firing condition.

It's not clear to me if this "elongated spark" situation might also lead to more rapid erosion of the electrodes in cap. Others may comment.

I believe it's been said that one purpose of the proper "cam retard" is that it enables sequential firing of the injectors; if the cam retard is out of spec, the ECU goes into batch-fire mode. Another purpose which has been mentioned is it enables the ECU to determine which cylinder is misfiring, when misfires occur. There may be other reasons.

Whether any of the above might lead to your hesitation is up for discussion.

 

[98 Nitro]

You need the GM hold down to adjust it, and the code doesn't pop up unless it is +-13 I believe. My UMP ran better with a Standard cap, though I didn't have their better cap.

 

[evilunclegrimace]

I just remove the fixed hold down and run TBI distributor hold downs on my UMP distributors and I can adjust the CMP offset.

 

[east302]

. I ordered a GM distributor hold down clamp, but not sure if that will make a difference.

I replaced my stock distributor with a Summit brand one a few years ago and it had the fixed bracket. The old (GM) bracket swapped onto the new distributor, so you should be ok.

 

[someotherguy]

This isn't an issue I've ever run into so I never paid much attention to it, but if you look at the various distributors listed for a small block Vortec, the pictures of a LOT of them clearly show the area where the hold-down clamp goes is not round - it's keyed with flats on two sides. The UMP 9362 appears the same. This would imply non-adjustable. Why, I don't know...

So I'd look into the hold down clamp as east302 mentioned. If you look it up on Rock, they show the same one for TBI and Vortec applications, GM 19433111 - no pic on Rock but if you look elsewhere it has very short tabs; I wonder if it just doesn't come into contact with the "keyed" area on the base of the Vortec distributor?

Some members were just discussing this issue with the hold-down clamp very recently. Here's the thread: https://www.gmt400.com/threads/need-assistance-please-any-input-is-welcome.65464 and you can see in the member's pic (screen shot next to last pic) that the Vortec hold-down grips the keyed area preventing it from being adjustable.

You must be registered for see images attach

Richard

 

[Road Trip]

So I'd look into the hold down clamp as east302 mentioned. If you look it up on Rock, they show the same one for TBI and Vortec applications, GM 19433111 - no pic on Rock but if you look elsewhere it has very short tabs; I wonder if it just doesn't come into contact with the "keyed" area on the base of the Vortec distributor?

And for a visual comparison, here's a clear pic of the GM #19433111 distributor hold down clamp
on the Paceperformance web site:

You must be registered for see images attach

This should do the trick -- clamping OEM good while not restricting your ability to
dial it in for CMP<>CKP synchronization. (Good on @someotherguy for the part # info.)

Cheers --

 

[Dean89]

Just wanted to say thank you to everyone that replied to this thread! The GM hold down clamp allowed me to rotate and set the cam retard to within spec (photo of GM clamp and UMP clamp attached). I believe my problem was due to the cap that came with the UMP distriburtor. As you can see from the attached photos, the UMP DCR820X is different with a vent hole. Hopefully this cap will last longer than 10K miles. Also, my problem occurred right after we had a hard freeze for a few days. Maybe ice/condensation played a role.

She's running beautifully again! And again, thanks for your help!!!