What the hell happened inside my distributor? Pictures inside

So I thought I had a carbuerator issue because the it didnt sound like a miss, and it drove fine at a higher RPM. Then I pull the distributor cap and find this. This is a Mallory 2092M distributor with vacuum advance.


So what I found was the center point underneath the where the coil wire comes in was completely burnt off, and the one side of the distributor cap has a giant gash in the side of it. Im guessing maybe an arc from a shorted wire? I have new wires that were just put on, and new plugs as well. Do you think it could have possibly taken anything else out in the ignition?

I need to add, when this problem started I found a plug wire had vibrated loose and was not connected to the plug. Upon pulling the wires i found the boots to be resting against the exhaust because they are incorrect wires, it could have possibly arced.

Im hoping this solves the issue. I had another post in the forum elsewhere but I took a break from the truck so that I didnt go spending money on something that wasnt an issue. Its good I did take that fresh look.

http://i22.photobucket.com/albums/b3...3/fe911303.jpg
http://i22.photobucket.com/albums/b3...3/1dbb0c7c.jpg
And the new one for reference.
http://i22.photobucket.com/albums/b3...3/40bbf8da.jpg

So upon tracing the plug wire it leads right to where the gash in the side of the cap starts. So is this what burnt off that coil lead inside the cap as well? What all should I replace?

Cap was loose, or the rotor came apart?????

Cap was pretty tight and the rotor is as well, I don't think that this is an old mark. It's almost too much of a coincidence that the scorch mark starts right where the point is that leads out to the plug wire that came loose. I'm just hoping it didn't damage anything else

Are the shaft bearings still tight? If so, could just be from the bad wire, pretty radical for just that, though???

I'd start with a new cap & rotor to go with your new plugs & wires and see how it does with them. Wouldn't think anything else would be hurt.

Yea the shaft bearings seem tight, there definitely is not enough play for that to happen in my opinion. I do have a new cap and rotor along with the proper plugs and wires now. Thanks! I'll be checking up on the cap that's for sure. I think if the bearings were bad it would have destroyed that cap instead of just one spot.

So that short could just burn that coil lead inside the cap that bad? Someone told me its an infamous Chevy thing. I can't see how it's " a Chevy thing "

I've seen that from flashing when the plug cannot "fire".. I haven't seen it when a wire or plug has shorted. I'd replace the cap and rotor for sure!

Well the wire did basically come unhooked from the plug while driving so it really didn't fire it. Not sure if that's what ya mean by not being able to fire, or if your referring to a combustion problem.

i do not think it.s bearing ...looks like the cap was not flat with the dist body rotor knock it back ...on track .. thats the mark ... the center contack carbon was burn off when it first fired up cap off center .you can see the burn track .like to see the old rotor .. if this mallory has spring clips it just pop on .i seen were the fire wall is to close car moves alot of frame flex /engine movement on engine mounts under a hard load and will knock the cap off center or a wire gets clip under the cap and dist body see this to .with the flex deal two cars come to mine one i own

Hmmm ok so maybe this isn't my whole problem. As of right now the truck dies at idle, and can barely get it started. As I said though I first thought it was my carb. Guess I'll see, I was told to fix the ignition issue first and go from there. I should know by the end of the day today.

I'm guessing two different 'things' happened. One was a cap that was installed cockeyed and the rotor tip gouged the side of the cap.

The second was that arcing at the center electrode. I have seen this happen when the condenser was of the wrong capacity in the old point system, which I'm thinking you do not have and secondly, when the coil is reverse installed. Also, if there is a starting resistor that is supposed to be in the system and was either left out or gone bad. Then there is that old bugaboo - just one of those mysteries. Happens once and not a dang thing that happened before or ever will again

well maybe but carbon looks like it broke off ? two things did happen first was the cocked cap . funny the burn track is the same side as the rotor cut . burn mark may happen when the contack was missing open up the gap.then you had a arc welder in the cap as juice is not going to want to run threw the wires to fire plugs very good . it ran fine before this ?...... photo of old rotor would help .... if no resistor in line to drop the 12 volts frys the points in the mallorys points will not take it full time . i had a YL many years ago changed many points before i learned that resistor was bad and 12volts full time did not make them happy. that was 30years ago :) start at the ign side of switch track every thing down check with volt meter . try another coil . new point. condenser .new rotor . make sure cap is seated .air gap is righ on points i think .016to 018 gets close . plug gap is right 0.35. it should run fine

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Originally Posted by 1923tbucket

Well the wire did basically come unhooked from the plug while driving so it really didn't fire it. Not sure if that's what ya mean by not being able to fire, or if your referring to a combustion problem.

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Nope, that's what I mean. The electricity had nowhere to go so it found the easiest way to ground (or on it's way to it.)

You still need to replace some parts and as mentioned check voltages going into the ignition system. If it is battery voltage and it's a 12 volt system, you'll need a resistor to lower it in half. (or there abouts)..

Just a personal preference but, on a 6 volt ignition system, I like to set the plugs around .030".. small difference but I think it helps cold starting..

I agree with Pat those are mechanical related and not arcing. Distributer rubbing the fire wall is a good thought, any external marks on the outside of the cap you could have overlooked? Your sure the cap was on correctly, you said the unit itself is in good shape. I to would also like to see the rotor that would be a key shot to put up as Dave Severson pointed out. The button to me shows mechanical or rubbing damage looks like the collar it lives in is chipped . How about those contacts under the scratched area, anything going on there, can not tell from the angle of the photo what the condition of them could be.

Based on the not wanting to start issue. The rotor was prob. broken and cocked. Bad motor mounts or torqing of the engine, like has been said, disti hits the fire wall, rotor hits the cap, breaks the plastic holding the rotor tang straight. Should have been noticed looking at the rotor. After you get it running check your motor mounts under load or it may do it again. Been there done that.

Yea this is a truck that's been driven a bit though so the existing system should be good. I just picked it up about a month ago and was driving it almost daily to get the bugs out of it. I'm hoping this is more of a freek thing and replacing the cap and rotor will be good. The rotor looks fine so.

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Originally Posted by sfort

Based on the not wanting to start issue. The rotor was prob. broken and cocked. Bad motor mounts or torqing of the engine, like has been said, disti hits the fire wall, rotor hits the cap, breaks the plastic holding the rotor tang straight. Should have been noticed looking at the rotor. After you get it running check your motor mounts under load or it may do it again. Been there done that.

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I'll check the mounts for sure, the rotor looks ok though

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Originally Posted by pepi

I agree with Pat those are mechanical related and not arcing. Distributer rubbing the fire wall is a good thought, any external marks on the outside of the cap you could have overlooked? Your sure the cap was on correctly, you said the unit itself is in good shape. I to would also like to see the rotor that would be a key shot to put up as Dave Severson pointed out. The button to me shows mechanical or rubbing damage looks like the collar it lives in is chipped . How about those contacts under the scratched area, anything going on there, can not tell from the angle of the photo what the condition of them could be.

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The contacts look ok, it's hard to tell but the cap isn't chipped but it is a scorch mark

Here's the rotor
http://i22.photobucket.com/albums/b3...3/92a71a2b.jpg

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Originally Posted by 1923tbucket

Yea this is a truck that's been driven a bit though so the existing system should be good. I just picked it up about a month ago and was driving it almost daily to get the bugs out of it. I'm hoping this is more of a freek thing and replacing the cap and rotor will be good. The rotor looks fine so.

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Oh now I get it this was a new toy so to speak and you really had no history/seat time in it. Well, then I guess you are finding bugs, the rotor looks ok and so good I think what you see in the cap may have been there the whole time and the button finally gave the ghost up. There may very well be nothing at all wrong in there, the last owner did not fix it right the first go around. New cap may be all that is needed.

Yea I did the cap and rotor anyways. Went to start it now I have a grinding noise. I'm done for the night now. I'm not sure if it's just a fluke with the starter or what, that's what it sounds like anyways.

That's hotrodding solving one problem at a time. It is worth the trouble in the end, not to mention all you learn as you go, before you know it you will run out of stuff to fix LOL .. Then your golden.

Yep I plan on doing ocean city with it next year in may. That's a 4 1/2 hour drive from where I am, but I'm looking forward to it

So she turns over nicely now and fire right up but stumbles as if out of time and dies. I could tell it got better by adjusting the distributor but it's as far advanced as it can physically go without rotor adjustment. So I need to get the harmonic balancer at the Tdc mark on the compression stroke so I can set the rotor at number 1. Normally I've done this by just cranking the nut on the balancer. Not this one. It has an accessory drive on the front and this motor has some crazy compression evidentially. Any suggestions without getting lucky by tapping the key?

Pull the plugs and rotate it with a breaker bar on the balancer nut. Sounds to me like you're a tooth off on the distributor relative to the cam. If you're out of adjustment room on the distributor, but not yet back to TDC you need to pull the distributor and move it back a tooth.

Here are a couple...Could just rewire the sockets on the cap using Chevy as an example; what is now plug wire #1 remove that and place it in the socket where #8 wire is; then put #8 wire in the socket where #4 wire is and continue all around, 1-8-4-3-6-5-7-2

I hope this is clear, the cap does not care what wire is in what socket as long as the order is correct. Could also just pull the distributor up and rotate it. If it is hitting the firewall now, clock the rotor more towards the fire wall that will move the sweet spot back or out from the firewall or whatever it is hitting.

Getting to TDC using the balancer bolt to rotate the motor is never a good idea, there is a great little fixture that attaches to the balancer . I will say that getting TDC and moving the rotor is the best and least trouble. The suggestions can take longer to achieve more advancement adjustability, the down side is going the wrong direction the first time. .

Move the wires as pepi suggested and then put a vacuum gauge on it and adjust the dist. for the highest reading and back it off just a tad and you will be awfully close.

Like Pat said I had that happen to me once.. broken motor mount engine rasied and moved cap.

Sorry for the delay guys, Im juggling overtime at work, college courses and term papers, trying to sell a t bucket, and roughly 6 hours a week at the gym.

Im going to get on it here after I get back from the gym tonight. When I was advancing the distributor it seemed to get better, I may still have a miss though. I verified my plug wire order on the distributor and it is correct. Im going to try to correct it by pulling the distributor and moving the rotor counter clock wise a tooth. I would move the plug wires but they are on there so tightly I dont feel like messing with them.

BTW on the carb. I tried adjusting fuel on the fly quick and did not count the turns. Its a 750 holley on a .030 over motor with a mild cam. I know the 351 on a 600 holley on my mustang rule of thumb was 1 1/2 turns out from fully seated to start.

I'd say that at some point in the past (before you got the truck) the cap was put on cockeyed with the rotor missing the inner electrodes and cutting into the cap a bit, likely no harm done as it did not start and was quickly corrected. However, the center carbon button was riding on the edge of the rotor electrode and got chewed up enough to start a bad wear pattern. Over time your center electrode eroded down and started arcing a bit, but your miss was due to the plug lead being loose, which coincidentally aligned with the cut in the cap. Those jets you adjusted on the fly only affect the idle circuit, up to about 900rpm or so. The easiest way to adjust them is with a vacuum gauge, setting them for the best vacuum at your selected rpm. Like I said before, I'd replace the cap and rotor and see if you can't forget about the distributor internals once you get your distributor clocked right with the cam to allow adjustment.

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Originally Posted by rspears

I'd say that at some point in the past (before you got the truck) the cap was put on cockeyed with the rotor missing the inner electrodes and cutting into the cap a bit, likely no harm done as it did not start and was quickly corrected. However, the center carbon button was riding on the edge of the rotor electrode and got chewed up enough to start a bad wear pattern. Over time your center electrode eroded down and started arcing a bit, but your miss was due to the plug lead being loose, which coincidentally aligned with the cut in the cap. Those jets you adjusted on the fly only affect the idle circuit, up to about 900rpm or so. The easiest way to adjust them is with a vacuum gauge, setting them for the best vacuum at your selected rpm. Like I said before, I'd replace the cap and rotor and see if you can't forget about the distributor internals once you get your distributor clocked right with the cam to allow adjustment.

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Yea thats about where im at, ive advanced the distributor as far as I can as far as clocking it. Its close but still there seems to either be a miss or its out of time, so im gonna have to pull it and advance it a tooth as the vacuum advance is now catching up on the firewall.

So now im about at my wits end with it, I tried getting the distributor out but its hitting on the fire wall so its almost impossible. So I go to seat it back in and the oil pump rod must of moved and now its going to be further out of time than what it was to start with. Add to it the wire harness leading up to the distributor is so damn short I dont even see how it made a connection to begin with, course now that its disconnected its an almost impossible feat to get reconnected.

Ok all the little issues are straightened out. Now any advice on rotating the oil pump rod so my rotor shaft lines up where I need it to?

I've always used a large slot screwdriver to line up the pump.

Yea I have a pretty good sized snap on one but can't seem to find the groove. I suppose I could just take the cap off and have my buddy bump the key until its where I need it.

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Originally Posted by 1923tbucket

Yea I have a pretty good sized snap on one but can't seem to find the groove. I suppose I could just take the cap off and have my buddy bump the key until its where I need it.

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NOPE! You need to keep # 1 cylinder at TDC.. Turn the oil pump drive, use a mirror to see down inside, you "may" be able to bump the starter while holding down the distributor, but you've got to get the alignment close before you bump it over.

Well I'm close. I mean a few degrees, to the point that I almost have it by clocking the distributor. Issue is with TDC on number 1 is that with my accessory drive I can't easily turn the balancer

Ya' know, I was reading one of the tech articles in a recent (July 2012 Hot Rod to the Rescue pg 106) Hot Rod mag where they were chasing a batch of problems on a '69 Camaro. Turned out that the pointer marking TDC was actually showing zero when it was retarded ten degrees. They did not know if the cause was a mis-indexed crank key, the wrong damper for the application, the wrong front cover (had a welded on timing tab) or some combination but they watched the #1 piston moving using a bore scope, and quickly noted that indicated TDC was retarded ten degrees. You might want to check your timing marks, and verify TDC before you go too much farther....

Here's a link to a method for verifying TDC - http://www.clubhotrod.com/chevy-smal...tml#post468480 You've still got to have a way to rotate the engine, but having all the plugs out will make it a lot easier.

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Originally Posted by 1923tbucket

Well I'm close. I mean a few degrees, to the point that I almost have it by clocking the distributor. Issue is with TDC on number 1 is that with my accessory drive I can't easily turn the balancer

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I once had a van that gave me the same problem. I actually went to the flywheel and used a prybar on the teeth to slowly turn the crankshaft while a helper monitored piston movement. Food for thought.