This morning the old Dodge was hard to start, ran rough, and was notably lacking in power. Grounding each plug with a screwdriver indicated that #1, #2, and #6 were firing, and that #3, #4, and #5 weren't. Placing the screwdriver next to the top of each non-firing plug produced no spark, telling me no current was coming to them from the distributor. I wasn't able to find any cracks in the cap. Filing and adjusting the points made no difference, and I wouldn't expect it to because that should affect all six cylinders equally. I guess the next thing is to check continuity of all the wires, but I doubt that three of them would go bad overnight. Yesterday the truck ran normally. What am I missing?

Possible damage to the rotor and/or the distributor cap contacts?

Also check the wires going into the cap. Time and moisture there can cause problems.

Kinda' wondered about worn distributor shaft bushings, but then with a firing order of 1-5-3-6-2-4, and #3, #4, and #5 being the ones that don't fire, maybe not. If the bushings are worn though, maybe opening up the point gap a bit would make a difference,....???

Might be worth a try (before tearing things apart) to wait 'till darkness tonight and fire the ol' girl up again and look for errant sparks that might help determine why 3 dead cylinders,.....harold

Actually Steve, assuming it ran okay when last used, a cracked distributor cap sure seems like a distinct possibility, but whatever the case, you can bet it's something minor,....harold

Okay,...here's one more "thought" and then I'll shut up!

No fire on three cylinders when grounding each plug w/screwdriver.

How about if ya' crank her over and by grounding the distributor end of the coil-to-distributor wire,....see if you seem to be getting 6 consecutive sparks with each compression stroke,....???

Okay, as promised, I'll shut up now. Knowing your "shade tree mechanic skills anyway Steve, this is a classic case of "preaching to the choir"! ..... harold

Odd. A quick look online indicates that the firing order is 153624, so the misfiring is spread around the distributor cap, not all on one side.

Interesting that the misfiring occurs in three cylinders in a row on the block, are those three plug wires bundled together and touching ground somewhere? If so, try unbundling them and lifting them up off of whatever metal parts they may be laying on.

Wind yer watch back 24 hours and then see how it runs.

Garnet

I don't know what kind of wires you have on your distributor, but some of them are not solid copper but are some type of carbon resistor. Those wires might be open or grounded. It happens quite often.
Norm

I think the wires are fine. Old time copper wires I installed myself. They still check OK for continuity, and the insulation appears almost like new. I'm leaning toward a distributor cap or rotor problem, though I cant see anything wrong with either one. But I have one other test to try before I go shopping.

Scrape the crust off the contacts inside the cap and the tip of the rotor. If that does not fix it convert it to six coils and a six position timer. Most reliable ignition system ever developed! Mine's been working just fine for a hundred years.

Capacitor?

My old '64 Valiant gave me problems ...although nothing visible to my eyes (and they were good awhile back) a new distributor cap cured its problem.

Good Luck

Clean the inside of the cap and make sure it's dry. Even bakalite caps can get carbon trails or if moisture is present get grounded.

Today I started with John's idea of cleaning the contacts. I wire brushed the rotor contact and all the ones in the cap. No dice. The truck still barely ran, which you might expect when only two cylinders are firing. Capacitor? Nope. That would affect all cylinders. One more time, with the engine running I grounded each plug. As before, only two were firing. But I noticed that when I checked the four that weren't firing, the screwdriver sparked against the head. So when I went to town for groceries I stopped at a parts store and spent $16.17 for this cure.




That did it. The truck now runs normally. Why would so many plugs go bad all at once? I have no idea, but installing six new ones sure solved the problem.

Steve, sometimes its best not to ask why, and just let the good karma flow. How are you coming along on the roadster?, you must be getting pretty close to firing her back up again.

Got the transmission and pan back on. Fourth main is next. It should be done by now, but I've been busy with other stuff.

Well good luck with it, I'm sure we'll hear it rumble back to life in due time.

I see you are taking advantage of good weather getting fire wood for splitting. How much fire wood do you normally use during the winter?
Making sure you have enough fire wood takes precedence over other fun projects.

Not as much as I used to. During cold weather I spend most of the day in my shop or the office above it. There I have gas heat. I'm in the house, with wood heat downstairs, in the evening. Upstairs the heat is electric blankets.

Steve, glad to hear you fixed the problem. If you haven't already tossed them, can you post pictures of the firing ends of the "bad" spark plugs? Thanks!

Change the Mac to a book and that would be straight from Norman Rockwell.

If Rockwell was drawing today that would probably be "period correct".

I see you also have a dangerous wood stove. We have had ours since 1982 and I love it. Lately, the wife has asked me to set with her and watch the fire with a glass of wine. Three or four hours later [and a nice nap later] I remember the not so important project. We are retired and I guess I'm still thawing out after all those cold railroad nights I had to work.

Joe R. Independence, Mo.