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Renix distributor rotational play limits?

Ecomike

NAXJA# 2091
NAXJA Member
Location
MilkyWay Galaxy
Any one know what the Renix distributor rotational play limits are? I have some obvious play in mine. Is it too much? I have no idea.
 
The gears are helical cut and the rotation along with centrifugal force is likely to seat the shaft fairly solidly.

One thing you can try is a timing light, if the timing mark is steady and doesn't jump around you are likely good to go.

IMO lateral play in the shaft from worn bushings is likely to be a bigger factor. Wobble can make the rotor to cap gap variable and erratic.

You can quick check your initial distributor setup at TDC 1, but in my experience the initial rotor position has a pretty wide envelope and the ECU adjusts.

Renix_Distributor_Intial_Setup.png
 
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I don't think the Renix distributors were all that much different than later ones. There shouldn't be much play rotationally. I want to say less than a 1/4" forwards and back total. Lateral play from worn bushings can cause a tick but is unlikely to cause running problems unless its truly excessive.

As far as I know the distributor gear is made softer so it will wear before the cam. The gears can last a very long time but in other cases they don't for whatever reason. We had a guy at last years Colorado Fest who's distributor blew out on Red Mountain Pass before he ever got to the trail. He started backfiring on the grade and pulled off to the shoulder. As I recall that one was so shot you could turn the rotor 1/8-1/4 turn or something like that. Basically the distributor gear was worn to nubs. Oddly he drove it all the way from Virginia Beach to Ouray before it happened.
 
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Not sure I understand your issue.., but.., seems I recall grasping rotor, and it moves just a 1/4 inch, more-or-less, and springs back. I could be all wet on that.

However, perhaps helpful is to consider the other end of the process by aligning two marks. (A) Getting rotor to point on #1, (on the distributor body), and (B) also having crank pulley timing mark on zero-ish.., (I cannot recall degrees advanced from TDC), and then turning the crank pulley nut backwards, (counterclockwise), should begin to move rotor.

I think the limits of turning/wrenching on the crank nut, (paying attention to the pulley notch mark movement), is just anywhere under one, and a half inch maximum. The rotor should move within that spec. Best to have extra eyeballs, or some scribe marks, magic marker, etc.

Without extra eyeballs, my easiest method was to use soapstone to scribe additional marks else wheres on cleaned surfaces as follows. After having gotten my factory alignments marks done topside, (rotor dist. notch/crank pulley notch), I'd go underneath, and place an arbitrary mark somewheres on the pulley, and another mark on an easy to view spot, timing cover etc., directly in correspondence from each other. From this position wrenching on the nut counterclockwise just bits at a time will show divergence enlarging the distance from, or between those two new marks.., turning away from each other. Once the rotor has just begun to move, I'd measure the distance those marks now appear apart.

After doing such a procedure a few times, one does not need to measure with a scale, but just a 'memory' look-see, to determine the spread to be within specs, or outside.

In order to 'not' unscrew the crank pulley nut, (which prevents this test), best to remove all spark plugs in order to not fight compression. Wrenching with plugs installed will most likely just unscrew the crank nut, and this test will thusly fail. THEN; 'ya have to tighten crank nut back up to specs, and try again. Easier for me to just remove plugs, (inspecting them too), before turning the crank nut which otherwise will, (often), want to unscrew from the crankshaft end.

Anyway the test above is for checking another problem, or not, perhaps in your case, but seems to provide an answer to your rotor play question as well. If your rotor is mostly tight to the distributor shaft, and your crank counter wrenching turns past 1.5 inches, say 2 inches, before rotor moves/turns.., you have that different problem. Poor memory, and without my FSM, I can go no further. Perhaps someone will chime in with better specifics.
 
Eyeballing it mine (87 Wagoneer XJ) has 1/4" to 3/8"of rotational freedom. But I got to thinking the helical gear may be riding up vertically as I rotate the rotor/assy, so maybe when the gear is engaged and Cam shaft is turning this goes away. So then there must be a proper way to test it???

My other 87 has about 1/2 as much movement as the Wagoneer I am de-gremlin-izing.. But I think mine has had a lot of movement for years. No lateral side to side movement that I can detect at all. Is the rotor rotation clock wise???

This one (AZ rebuilt) is about 11 years and 70,000 miles old on the Dizzy.
I don't think the Renix distributors were all that much different than later ones. There shouldn't be much play rotationally. I want to say less than a 1/4" forwards and back total. Lateral play from worn bushings can cause a tick but is unlikely to cause running problems unless its truly excessive.

As far as I know the distributor gear is made softer so it will wear before the cam. The gears can last a very long time but in other cases they don't for whatever reason. We had a guy at last years Colorado Fest who's distributor blew out on Red Mountain Pass before he ever got to the trail. He started backfiring on the grade and pulled off to the shoulder. As I recall that one was so shot you could turn the rotor 1/8-1/4 turn or something like that. Basically the distributor gear was worn to nubs. Oddly he drove it all the way from Virginia Beach to Ouray before it happened.
 
8Mud, what is the .020" all about in the image?

My 87-Wag rig is barely running at 500 rpm and choking and puking now, at idle and at WOT. Hard to get any running data at all now. Check my other post in a bit for a new update, and for a reply I already sent you.

The gears are helical cut and the rotation along with centrifugal force is likely to seat the shaft fairly solidly.

One thing you can try is a timing light, if the timing mark is steady and doesn't jump around you are likely good to go.

IMO lateral play in the shaft from worn bushings is likely to be a bigger factor. Wobble can make the rotor to cap gap variable and erratic.

You can quick check your initial distributor setup at TDC 1, but in my experience the initial rotor position has a pretty wide envelope and the ECU adjusts.

Renix_Distributor_Intial_Setup.png
 
The rotor rotates clockwise following engine firing order 153624. Wires should be placed accordingly.
 
The gears are helical cut and the rotation along with centrifugal force is likely to seat the shaft fairly solidly.

One thing you can try is a timing light, if the timing mark is steady and doesn't jump around you are likely good to go.

IMO lateral play in the shaft from worn bushings is likely to be a bigger factor. Wobble can make the rotor to cap gap variable and erratic.

You can quick check your initial distributor setup at TDC 1, but in my experience the initial rotor position has a pretty wide envelope and the ECU adjusts.

Renix_Distributor_Intial_Setup.png

Not so in Renix as far as adjusting.

Here’s WHY distributor indexing is so important:

Distributor indexing explained
For clarification though, that’s not a cam sensor inside the Renix dizzy. It’s there to fire the injectors sequentially with the firing order. You’ll never notice if it went bad because the ECU will try to “guess” where it is and does a heck of a job at it.

As for the “timing”, it is controlled by the ECU. Ever notice how wide the tip of the rotor is? Try and wrap your head around this:

When the ECU yells “Fire” to the ignition control module, where is the rotor in relationship to the dizzy terminal? Not to the terminal yet? Past the terminal too far?

What happens to the spark/secondary ignition strength when it has to jump the Grand Canyon in comparison to shooting from a rotor tip?
 
Short of installing a defectively built Distributor that was not assembled properly, or using a 91-2000 dizzy, I never understood what the purpose of the indexing was. My distributor has worked perfectly, for 11 years, 70,000 miles with no issues since I replaced it 11 years ago. It still has the tab that keeps it from being able to move or be indexed. it is fixed.

I see that indexing write up in the Snap-on troubleshooting manual as a fix for stumbling, but it does not say why. I recall that only being needed when there was a problem with the dizzy being used to replace a bad one.

Did you ever run across any other reasons for doing it? A properly built Dizzy should be self indexing buy the tab that bolt goes into, one just has to do the 4 o'clock deal and grab the proper gear tooth.
 
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Short of installing a defectively built Distributor that was not assembled properly, or using a 91-2000 dizzy, I never understood what the purpose of the indexing was. My distributor has worked perfectly, for 11 years, 70,000 miles with no issues since I replaced it 11 years ago.

I see that indexing write up in the Snap-on troubleshooting manual as a fix for stumbling, but it does not say why. I recall that only being needed when there was a problem with the dizzy being used to replace a bad one.

Did you ever run across any other reasons for doing it? A properly built Dizzy should be self indexing, one just has to do the 4 o'clock deal and grab the proper gear tooth.

Post 8 tells you why.
 
Post 8 tells you why.

That does not explain why a working for years distributor would later need indexing, and not just replacing it.

I will rephrase. Why did it suddenly need indexing, unless it was defectively built in the first place?

No where does it explain what has gone wrong that indexing fixes. Every thread I ever read that did the indexing was after a dizzy had been installed and had it on the wrong tooth, or had a dizzy with the Tab already cut.
Once they got it installed on the right tooth they were OK.

Mine has so much rotational slop, I am not even sure where it sits when rotating, but IIRC it has had 1/4" of rotational slop for 11 years since it was new. I think it is just slop between the helical gears. That rotor covers such a huge swath I don't see how it could miss fire. Its like shooting a shotgun at a Barn LOL.
 
With out understanding why? I checked it with the cap off, and just like the last 11 years the rotor points right dead on at the post, maybe a 1/16-1/8" past dead on center (hard to tell with all the rotational slop, I rotated the rotor in both directions to see what the limits were that way, can't do that with a cap in the way). It has not changed and has worked perfectly for 70,000 miles. Never saw no need for messing with cutting a cap. I just mark the side of the Dizzy where the #1 post is and use that.

What I want to know is what the factory limits are or slop in the dizzy gear teeth mesh, rotational limits of slop? If there even is such a thing?
 
Does the later model procedure not work? Something like turn the flat head screw to 11 o'clock and put the dizzy in at 1 o'clock and it will wind back so everything lines up and the hold down lines up perfectly not work on Renix?

I know that's the procedure on post Renix era engines and if it don't work something is out of time and it won't work with a poop.
 
Does the later model procedure not work? Something like turn the flat head screw to 11 o'clock and put the dizzy in at 1 o'clock and it will wind back so everything lines up and the hold down lines up perfectly not work on Renix?

I know that's the procedure on post Renix era engines and if it don't work something is out of time and it won't work with a poop.

Totally different as the deally bob inside a Renix dizzy has NOTHING to do with cam timing or spark.

The indexing was a problem when new and is on rebuilt units.
 
Does the later model procedure not work? Something like turn the flat head screw to 11 o'clock and put the dizzy in at 1 o'clock and it will wind back so everything lines up and the hold down lines up perfectly not work on Renix?

I know that's the procedure on post Renix era engines and if it don't work something is out of time and it won't work with a poop.

It worked perfectly on my Renix, 87 XJ-Wagoneer 4.0, 11 years ago installing a rebuilt Autozone Dizzy. The one I am working on a super rich issue with. My old one was throwing oil into the cap 11 years ago.

Its put the dizzy in at 4 o'clock and it turns and stops at 5 o'clock.The rest you got right.
 
Sacrifice a cap and do the procedure.

Why, mine is already located where that procedure says it should be set at? It has worked there for 11 years?

That write up you have use to say in one of the versions I have seen over the years, to only do it if the rotor was not locating in the proper place. Mine is and has been already.
 
I read the TSB years ago, it said as best as I can remember, that there was a batch of cams that where the distributor drive and the initial cam setup was a slight mismatch. The rotor tip is broad, but to the best of my understanding is that ECU can run out of timing if the rotor tip isn't near the middle of the setup envelope.

Timing chain slop, worn gears or whatever can cause initial setup rotor position to change a little. My 89 was pretty far off, I corrected it.

After market cams for years were speced to the early Renix cams where the clocking was a little off and the distributors also needed to be re indexed.

One thing most everybody forgets about is that distributor shaft shear pin. It doesn't have to break completely. It can break and the sharp pin ends can kind of catch again fairly solidly, the rotor has moved from initial setup position but you may never know unless you look (check the indexing). The wifes 87 had a CPS issue, something weird happened, one cold morning it flashed back through the TB, maybe ran in reverse a little and blew the check valve cover off the booster. Idled like crap afterwords, I initially thought it had damaged something internally in the engine. On a hunch and having learned on old Dodge and Chevy carburetor motors, where shaft pin breakage was fairly common, I grabbed the rotor and twisted hard, the pin had snapped but caught and jammed again almost solid.

If it isn't something common and normal it is time to start looking at the odd and unusual.
 
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Well I know more now, there is rotational limit on the dizzy. Mine was out of limits, The sheer pin holding the gear to the shaft on the dizzy on mine was failing, and finally died, completely today, but not before I got it running well at 3500 rpm for 3 minutes that confirmed it was not the valve train!!!! So no need to pull the head, :)

It was also mildly hitting the sensor inside.
 
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