Very strange coil experience..........

My 73B roadster with Pertronix ignition has been running rough intermittently since the heater valve leaked onto the distributor last week. I thought it was better once the distributor dried out but the problem persisted over the past few days. Occasionally it ran just fine but most of the time it was rough.......as though it was way too rich.

Today I worked on it some more. The timing was right on (so the #1 plug had to be on the right spot on the dist. cap) and all plug cables were on the distributor correctly.

I checked for spark at all 4 plugs and it was fine. Then I checked the plugs and they were badly fouled with black soot. However, I hadn't touched the carbs at all during this process, so unless an internal needle problem had developed that was not the cause of the problem.

I wondered if maybe the coil had somehow been damaged (not putting out full power) when the antifreeze got into the distributor so decided to swap it out. While making the change I discovered one of the white/black wires on the negative coil terminal was hanging on by a thread, and then immediately broke off. Obviously that could be the problem so I decided to see if the car would start with it broken off. It started and ran.......albeit still very poorly.

I repaired the terminal and got both white/black wires back on the negative coil spade connector. The car started up a bit rough, but shortly thereafter was idling better. During a subsequent 10 mile highway/local roads test drive the car ran great. Assuming it is still good in the morning I'd say the broken wire was the problem.

However...........I'm confused by this. The Advance Auto Wire schematic shows my two white/black wires on the negative coil terminal go to the tach and the distributor. I can understand that if the wire to the distributor had a weak connection I'd be getting intermittent spark.....and hence, sooty plugs. However, since the car ran without the wire connected, it seems it had to be the wire to the tach that was broken. However, if the tach wire was broken off it seems that would have no effect on how the car ran.

Can someone shed some light on this?

Thanks,
BH

My guess is that you had a combination of problems. In 1973 (?) they switched to a voltage sensing tachometer - so a break in the tach wire will have no effect on the operation of the engine. (The older, current sensing tach had all of the distributor current passing through the tach - so a break in the wire would shut down the engine). I *suspect* that the water from the heater valve may have gotten under the connectors and caused a poor connection or a slight short. In the course of your repairs you probably dried and reseated all of the connectors.

At least, that is my theory.

Thanks Terry. I'm beginning to think the same thing. The tach wire probably broke off due to corrosion in the terminal fitting that was also affecting the dist. wire. The additional moisture from the valve leak (and/or a test drive in the rain the other day) could have been making for a weak electrical connection. Putting on the new female spade connector solidly connected to the fresh wire ends could have solved the problem.

I'm now thinking that a complete refreshing of all terminals (and fuse box too) under the hood would make a nice winter afternoon project !


BH

Pertronix FlameThrower Coils are currently on recall. The OEM in China made a bunch of bad units. Do A search, there was a topic not long ago on this. I had two new Pertronix coils fail on me in 6 months.

John,

I saw that post on the coils. I don't have the Pertronix coil......just the electronic ignition. Is there any advantage to getting their coil over a standard coil (once they straighten out the problem with the recall that is)? My car is just a daily driver as vs. a "performance" vehicle.

Thanks,
BH