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Mopar distributor advance plate wobble

Posted By: pjc360

Mopar distributor advance plate wobble - 07/15/17 03:45 AM

what are some tips and tricks to keep the advance plate more steady in the distributor?
I had to change the pick up coil in the distributor the other day.
I set the reluctor air gap to .008 like specified by Mopar.
But the problem is once the vaccum advance is applied the reluctor teeth start smacking into the pick up coil post because of how bad the advance plate wobbles around.
Is there anything else I can use to hold the pick up coil unit to the advance plate other then that strange little triangle shaped clip that comes in these distributors?
I feel like thats the problem area right there.
If there is anything I can do, like maybe a snap ring that fits tighter or maybe wrapping the little post that is on the pick up coil plate that goes through the advance plate with some tape or something to make the fit a little more snug?
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 04:00 AM

Being there done that, one of the headaches on this dist

I played bending the pickup coil bracket a bit here and there untill get the nicest position as posible. Got to made .007~.009 between both positions

Also check how much free play between pivot stud and plate hole. I used a bit of teflon tape on stud trying to make it fit a bit tight into hole
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 04:04 AM

It's imposible to make a perfect gap between both positions because the reluctor and the pickup coil draw unparalleled circunferences between them
Posted By: pjc360

Re: Mopar distributor advance plate wobble - 07/15/17 04:23 AM

I'm not so much worried about it being perfect, I just don't want the reluctor smacking the pick up coil post.
Im gonna pull the distributor again this weekend and mess around with it, see if I can't get it working better.
Posted By: RapidRobert

Re: Mopar distributor advance plate wobble - 07/15/17 02:41 PM

if the pivot pin and or the hole are wallowed out then they would need to be drilled out/replaced with something (not sure what) cuz if it is sloppy there is no getting around that.
Posted By: Supercuda

Re: Mopar distributor advance plate wobble - 07/15/17 02:41 PM

It's one of those get it to work as best you can with .008" clearance being the closest approach at the tightest spot.

Unless you want to redesign the guts.
Posted By: RapidRobert

Re: Mopar distributor advance plate wobble - 07/15/17 02:49 PM

Nacho I remember way back when you did that (bent it to get minimal gap change). I always wondered how the decreasing magnetic field cuz of the increased gap would affect triggering (timing). & the gap is the closest with no vacuum & the can vastly increases the gap. EDIT I reread your post & you might put a THIN washer under the top plate before you set the plate & pin into the bottom plate so the triangle clip will hold it tighter and if you still have some play you might slightly push the magnet closer to the tooth to take up some of that play then set the gap to .008" or simpler yet just increase the gap a few thousands to avoid the sloppy induced contact. when you see how far the gap increases from the can you'll know a few extra thou wont make a difference in starting. best would be to tighten up the pin fit.
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 03:47 PM

The gap change is not just due the plates free play, but the geometrical defect. We can try to save the plates free play on anyway you want, but the pick up still can bite the reluctor when vacuum works depending on the shape manufacturer gave to the asembly. Two problems to attack.

I selected to make somehow a tighter stud on plate hole with teflon tape over, which wraps the stud easilly and allows the pivot to work, since teflon is soft and somehow "lubed". Its also cheap and what I had handy. Maybe having a machine shop around could be made something better? Bush/sleeve the stud and get it tighter on hole?

Can't talk about voltage and timming variations due the gap change. Don't think something to worry as far you are within specs. I just try to set 0.008 average.

I also mill a bit the pickup end to make it flat/parallel against the reluctor.

I also measured EVERY reluctor point against the pickup and milled a bit each one to get them equalized, because the reluctor pin can set OUT of the shaft center the reluctor itself, so the reluctor ends on the pin side can be closer to the pickup coil, DEPENDING on how tight fits the reluctor on shaft

Dunno if is clear what I told
Posted By: 62maxwgn

Re: Mopar distributor advance plate wobble - 07/15/17 05:29 PM

Originally Posted By pjc360
what are some tips and tricks to keep the advance plate more steady in the distributor?
I had to change the pick up coil in the distributor the other day.
I set the reluctor air gap to .008 like specified by Mopar.
But the problem is once the vaccum advance is applied the reluctor teeth start smacking into the pick up coil post because of how bad the advance plate wobbles around.
Is there anything else I can use to hold the pick up coil unit to the advance plate other then that strange little triangle shaped clip that comes in these distributors?
I feel like thats the problem area right there.
If there is anything I can do, like maybe a snap ring that fits tighter or maybe wrapping the little post that is on the pick up coil plate that goes through the advance plate with some tape or something to make the fit a little more snug?


Why do you suppose the millions that were made didn't have that problem when new ?
Posted By: pjc360

Re: Mopar distributor advance plate wobble - 07/15/17 08:26 PM

Honestly I think they have all had that problem even when new.
I think it's just the way these distributors pick up coils and advance plates were designed.
I have to admit I love mopars and everything but the design of this pick up coil and advance plate isn't my favorite.
Now I'm to the point of considering just buying a firecore distributor, although I'm not sure if the firecore distributors have the same pick up coil and advance plate.
What pisses me off is Don at Fbo systems claims to solve these issues by welding the pick up coil plate and advance plate where most of the slop comes from and the one I bought from him looks 100 percent stock inside, no modifications to the advance plate or pick
Up coil at all.
So I'm at a point of do I pull this distributor out and attempt to get the pick up coil and advance plate tighter in the distributor or should I just throw this thing in the garbage and buy a firecore.
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 08:52 PM

yes, they have the same pickup coil. I also have wondered about how are they built to save this design defects.

Bud, it can be done. I made to make them work better in one morning... Is a trial and error process bending the coil angle againts the reluctor. A tiny touch makes a large difference.

and of course find the way the pivot fits tight into the lower plate hole

as I told, BTDT
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 09:06 PM

another problem to beat is the coil bracket to plate rivet... LOT of free play there BUT once screw is tight, is not anymore a problem really. Just think on that adjusting the gap or bending the coil bracket
Posted By: pjc360

Re: Mopar distributor advance plate wobble - 07/15/17 09:13 PM

Originally Posted By NachoRT74
yes, they have the same pickup coil. I also have wondered about how are they built to save this design defects.

Bud, it can be done. I made to make them work better in one morning... Is a trial and error process bending the coil angle againts the reluctor. A tiny touch makes a large difference.

and of course find the way the pivot fits tight into the lower plate hole

as I told, BTDT


What do you mean by bending the coil angle against the reluctor?
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 10:05 PM

nothing mode nothing less than what I told... the coil bracket can be bent to adjust the angle attack to the reluctor.

since is imposible to make a perfect position in rest and vacuum on position because geometry, you can try to get it the best as posible in both positions bending the coil bracket
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 10:18 PM

a MINIMAL touch will make a huge difference. You'll notice it.

is a trial and error process... bend, readjust screw, aply vacuum, bend, readjust screw... sometimes will requiere to get it back and try again.

IF POSIBLE hold with vicegrips the magnet section of the brackets to be sure the magnet won't get loose from the assembly or get a gap there being the bracket bent. It needs to be bend out of the magnet area ( yellow circle )

YES IS TRICKY AND NEEDS PATIENTE!!! will require dissasembly many times as necesary. Reluctor is easy to be installed and reinstalled many times as needed to get room to the vicegrips.



Attached picture pickup coil bracket job.jpg
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 10:39 PM

this is what happens on our dist

two diff circles Smaller reluctor, bigger the pickup coil. Note different ratios and centers. This make get closer the pickup coil to reluctor when vacuum works

bending the bracket will make the pick up coil end attack on a diff angle over the reluctor points even the pivot will make it move on same circunference when vacuum is present.

( not a perfect diagram, but representative )

Attached picture diff ratios dist.jpg
Posted By: NachoRT74

Re: Mopar distributor advance plate wobble - 07/15/17 10:49 PM

need to check how much is advancing the vacuum too... there is a small allen screw inside the tee... 3/32" I think. That can get shortened or enlarged the vacuum action so then the pickup travel. Maybe the vacuum can be getting a larger action that needed, getting the pickup even closer.

Everything will depend also of course on the timming required for your specific engine assembly. This check is not to save the pickup coil from bite the reluctor, just to be sure you are set right on there without unneeded pickup travel

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