how do I fix my distributor cap?

[gusbratz]

When I first resurected my m37 it ran good, very smoothe. After a couple days it started missing. I found the problem was in the dist cap. I took my fluke and put a probe into the hole where the wire goes and another on the little brass nub inside the cap I had no continuity. I discovered that the brass does not go all the way through the plastic casting. it has a spring and a small piece of carbon in there held in place my a sharp edged washer(which is what you see when you look into the hole from the top) I don't know why, maybe rf supression or something. i also noted china man marks on the cap leading my to believe that is was after market junk.
I then bought a new old stock one off of ebay. came all the way from saigon. made in america. it is the same way. truck is only running on 3 cyl because I have no spark on a couple wires. has anybody had a problem like this? I was thinking about pulling the stuff out and filling the holes with molten lead. or putting long springs in there. I relly thought a new cap would be the solution.

[Charles Talbert]

The newer caps available today are much better than what you have obtained. We had a fair bit of trouble out of caps when these were all that were to be had. With the new caps, haven't had a cap issue in several years now. We have them available for $40 each, plus shipping.

[gusbratz]

oh. who is we? Im going to try to get mine working but if I find it in the least unreliable I will buy one.

[Gordon Maney]

oh. who is we? Im going to try to get mine working but if I find it in the least unreliable I will buy one.

The name of Charles' business is in his signature, M-series Rebuild.

His company website is here.

Charles runs a first class operation.

[gusbratz]

still only running on 3 cyl. I took the old and new caps, drilled out the springs and washers and bits of carbon. filled the holes with solder. assembeled the plastic cap into the aluminium cover, assembeled all the wires and have no resistance from the nub in the dist cap to the plug end of the wire. put it all together and it only runs on 1 3 and 5. 2 4 and 6 are along the bottom arc of where the rotor turns so i loosened up the machine screws holding the cap down and shifted the cap all around and it will not fire on those bottom wires, is there supposed to be a gasket in there that will shim the cap up or down or something? I just can't figure out why on both old and new caps with no resistance from the brass contanct inside to the plug and i cant get spark. any ideas?

[Charles Talbert]

There is suppose to be rubber seals around each cap tower to make a water tight fit between the inner cap and the top cover. This does shim the inner cap downward slightly, maybe 1/16" or so. I've seen many running well without the seals installed, so I highly doubt adding them to yours will fix your problem.

Is your distributor in other wise good condition? Are the shaft bushings loose? Any side wise shaft motion is too much. Is the cam wobbling around at all on the top end of the shaft, this will also cause similar issues.

[gusbratz]

the rubber washers are little commpressed with age but are in place. I cant wobble the shaft around in the distributor but I did not remove it from the truck because I am afraid of struggling to retime it. the rotor does wobble around on the shaft. I am replaceing the rotor next. I wonder if I could replace the entire distributor with a regular one from something else that used the 230 flathead. i did make some relly nice wires for mine that allow me to use normal spark plugs.and put new points into it allready though. i was real frustrated the other day and was ready to give up...

[Charles Talbert]

the rubber washers are little commpressed with age but are in place. I cant wobble the shaft around in the distributor but I did not remove it from the truck because I am afraid of struggling to retime it. the rotor does wobble around on the shaft. I am replaceing the rotor next. I wonder if I could replace the entire distributor with a regular one from something else that used the 230 flathead. i did make some relly nice wires for mine that allow me to use normal spark plugs.and put new points into it allready though. i was real frustrated the other day and was ready to give up...

If the rotor is wobbling, that is likely the issue causing your problem. If you have replaced the points, you also need to replace the condensor, always replace points and condensor at the same time.

Removing and reinstalling the distributor is no problem. The military distributor is a way better system than anything else you can change out to. A civilian distributor can not be used unless you change the oil pump also, as the drive shafts are different.

[gusbratz]

new rotor arrived, still missing on 3 cyl's. pulled the dist and inspected. I measure .30 axial freeplay with a set of feeler gauges between thrust collor under houseing on shaft and a visible radial play by watching the points gap while I flex the drive shaft from side to side. Guess that new bearings will be next.can anyone tell me how different is the oil pump drive shaft on the civilian engine? I am still thinking about swithching to a regular distributor.

[Charles Talbert]

new rotor arrived, still missing on 3 cyl's. pulled the dist and inspected. I measure .30 axial freeplay with a set of feeler gauges between thrust collor under houseing on shaft and a visible radial play by watching the points gap while I flex the drive shaft from side to side. Guess that new bearings will be next.can anyone tell me how different is the oil pump drive shaft on the civilian engine? I am still thinking about swithching to a regular distributor.

You will have to change over to a civilian type oil pump. You will need a Melling #M37 pump. Should be available locally at any good parts outlet. This pump is compatible with the civilan distributor shaft.

My recommendation would be to rebuild the military distributor and keep using it; it is a far better unit once you get it right.

[gusbratz]

I just can't get it. I took it apart and found such a tiny amount of play in the bushings i cant believe it would be this drastic, i drove the bushings out and took a prick punch and spiked up the inside of them, put it back together now no play in bushings. put rotor on and put a big gob of paint on it with a paint stick and put the cap on. sure enough it is comeing close enough to the top 3 points on the cap to leave paint but not on the lower 3. there is no play in anything now. I have to use vise grips to turn the dist.

i can't see rebuiling it. it has everything new cap rotor points cond. all new except busnings and they are tight for now. the weight advance is pretty tight. it is like the cap doesnt line up when it is tightened down but the way that aluminium cover has a beveled lip it can only go one way.

I'm very frustrated with this truck and right now am wishing i had never bought it. but with the plow mounts hyd pump work and power steering box all brakes and lines pulling head time money work ect I am beyond the point of no return. I am either going to find a good working distributor or cut mine in half and weld it to one out of a chevy 250 straight 6. that would get me HEI and no points.

[Gordon Maney]

I just can't get it. I took it apart and found such a tiny amount of play in the bushings i cant believe it would be this drastic, i drove the bushings out and took a prick punch and spiked up the inside of them, put it back together now no play in bushings. put rotor on and put a big gob of paint on it with a paint stick and put the cap on. sure enough it is comeing close enough to the top 3 points on the cap to leave paint but not on the lower 3. there is no play in anything now. I have to use vise grips to turn the dist.

i can't see rebuiling it. it has everything new cap rotor points cond. all new except busnings and they are tight for now. the weight advance is pretty tight. it is like the cap doesnt line up when it is tightened down but the way that aluminium cover has a beveled lip it can only go one way.

I'm very frustrated with this truck and right now am wishing i had never bought it. but with the plow mounts hyd pump work and power steering box all brakes and lines pulling head time money work ect I am beyond the point of no return. I am either going to find a good working distributor or cut mine in half and weld it to one out of a chevy 250 straight 6. that would get me HEI and no points.

I think you are over-reacting here. Calm down.

Punching the bushings is no way to fix that issue, as those punch marks won't last long. That is just not the way to do that. Upsetting a surface with a punch is a good method for some things, but not this one.

Those contacts are not supposed to touch, they pass close by one another, but don't touch. Your paint test is without value.

Your weld two distributors together would be a huge step backwards with respect to a number of things.

There may be something you are not seeing. Take a break, leave it for a week, and then come back.

[Charles Talbert]

Correct procedures

I don't want to offend you in any way; I've been trying to help you get on the right path. I guess there comes a time when nothing else but plain honesty stands a chance at working, so here is my best shot and you can do with it as you will.

The fix you have done with the shaft bushings is worse than bad. Bushings have to be installed and reamed correctly, precisely in alignment, and to the correct ID. The fact that you are turning the shaft with vise grips is plain awful in my best description. Obviously the pricking you did got it too tight and likely messed up the shaft alignment worse than when you started. Shaft wobble is now a factor if it was not before.

I really can't see why you would even bother to get frustrated, the methods you describe are truthfully frustrations best feeding source. You will have to stop and realize you aren't fixing the loose wheel on the covered wagon; what you are dealing with requires precision, and correct tooling for the job. You are just not approaching this situation that way. Even if you got it to run, there is a very high likelyhood that you would not plow much, if any snow before the frustration would set in again.

I'm just a straight forward guy as all the regulars here know, I'd like to help you get going and will do what I can to accomplish that; but you will have to get on the right path to addressing the problem correctly before anyone can assist further I think. One other fact you will have to get a grip on is that everything can't be fixed without some finacial investment. Nothing wrong with working on a budget, but some things require a little cash. We all must realize, there is reality.

[Charles Talbert]

Well Gordon, I see we were typing at the same time, sounds like at least we are on the same page.

[gusbratz]

I just pricked the busings to see if tightening it up would help, I know that will only last long enough for god to get the news.truck has like 57,000 miles on it and that must be a lot for one of these. You are right on all counts I am going to move on to another area for a while and give this a break while I calm down and search for another dist.