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Distributor Shake Rattle Roll

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malice

malice

Senior Member
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Hey my distributor has a little bit of excessive roll in it. Is that a problem?
 
Please define what you mean by : "Excessive Roll"---??--Keoke
 
Emm looks like it is "rolling" in its slot. I guess its just about a cm or so as it goes round.
 
Hello Malice,

are you trying to describe excessive sideways movement, i.e worn spindle bearings. If so that is not good and a recondition distributor is required.

Alec
 
Yup. What would be considered an excessive amount?
 
If you take the distributor off the engine, and try to wiggle the shaft, it should have virtually no side to side motion. However, make sure you are not confusing SHAFT wiggle with the various bits which move back and forth to control spark advance.
The shaft runs through a brass bushing. I can't imagine that the engine could run if the shaft had a cm of wiggle space! Why don't you post a picture so that we all know that we are talking about the same thing?
 
I'd like to elaborate a little on 70herlad's & Piman's comments and what you've observed.

You said: "I guess its just about a cm or so as it goes round."

A cm is slightly more than 3/8 inch. That's a lot for anything. However, how are you measuring this? Piman pointed out that you should not confuse this with the motion necessary for spark advance.

IF you are observing this 3/8" of movement by grabbing the dizzy shaft or rotor and TWISTING it, that's more or less normal. That motion is necessary for the distributor's centrifugal advance.

IF you are pushing the distributor shaft to the side (radially toward or away from the center), 3/8" of play would not only be bad... I don't see how your car could run. With that much play your rotor would be chewing into the contacts of the distributor cap.

Please describe a little better what you're doing to create and measure the play you observed.
 
ITs not just in the rotor. It looks like the entire unit.
 
I guess I should mention that the cap and rotor are in good shape, and the vacuum advance is working properly.
 
malice said:
ITs not just in the rotor. It looks like the entire unit.
Click to expand...

It would appear that if the entire unit is moving the clamp assemby may be loose--Keoke-??
 
If the entire unit moves (even with the clamp loose), then IMO something is bent and should be addressed. It may not hurt anything immediately, but it will cause drastic wear in places like the bushing that carries the shaft; and the clamp that is loose. Just tightening the clamp is not the solution (since the shaft or whatever will still be bent and now transmitting excess force to the bushing, etc.)

And whatever is bent may well decide to break after some time at higher rpm.
 
Perhaps you could post some pictures of what's going on it would help.
 
I grabbed the dist and gave it a shake this morning. It moved about 2-3mm, if that. Guess its not as severe as I thought. Looks worse than it is. Haven't checked the clamp yet.
 
As 70herald suggests, take the distributor out. Its very easy to do, just loosen the clamp and unplug the electronics connector.

If you have any significant movement in the shaft (e.g. from bearing wear) you will not be able to get a consistent gap for the electronic pickup, and you'll probably have erratic timing. In fact, if its wobbling a lot, you will see where the pickup has been getting scraped a bit from the rotating reluctor.

Rebuilds are pretty inexpensive. Check out our forum supporting vendors.
 
Being rather slow... I missed this was a '79. Does this automatically mean it came with factory electronic ignition? If so... what would cause wear in the dizzy bushings?
 
dklawson said:
If so... what would cause wear in the dizzy bushings?
Click to expand...
I'm assuming too that it is electronic, but I'm not sure why it would make much difference in terms of shaft bushing wear.

The shaft has to rotate as much in the electronic version as in the mechanical points model. Similarly, the advance mechanism springs and plates are the same design as in the mechanical version. About the only stress difference I can see is that there are no points to exert pressure on a cam and on the dizzy shaft. It would seem to me everything else would wear in the same way.
 
Ross, that's my point. The bob weights for the centrifugal advance don't put any load on the bushings. They are diametrically opposed to each other for balance and they spin on/with the rotating shaft so they introduce no load on the bushings. The only load that causes wear on most distributor components is the force of the spring on the contact points (always pushing to one side). Without that I don't see why the bushings should wear at all unless they were allowed to run completely dry (no oil) and then water got inside. One of the beauties of electronic ignition is that there is no side load on the rotating parts and therefore the mechanical bits are supposed to last much longer.
 
dklawson said:
The bob weights for the centrifugal advance don't put any load on the bushings. They are diametrically opposed to each other for balance and they spin on/with the rotating shaft so they introduce no load on the bushings.
Click to expand...

Only if they are the EXACT same weight, and precisely located at the EXACT same distance from the center and are EXACTLY in line with each other. Now, as I recall normally, the two weights are different in order to get the somewhat complex curve which is needed for proper operation of the engine. So you already have a built in imbalance, and that is before we start wondering about manufacturing precision. The of course you have different spring rates on each weight so the center of mass of each weight are always at different distances from the center from each other. (one is always more extended than the other) All sorts of loading going on in the distributor. And then when is the last time you really put a drop of oil into the distributor like the service instructions call for /bcforum/images/%%GRAEMLIN_URL%%/blush.gif
The electronic ignition will eliminate problems with wear on the CAM which opens and closes the points, but wont solve problems with a worn bearing.
 
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