Ignition Failure

[Patrick67BJ8]

Thanks all for your thoughts. I'll be investigating the suggestions. A couple of new details. I installed the original coil and had 8 volts (using my Harbor Freight multimeter) with the key on. The battery checked at 12.4 volts. The car has been idle for two weeks. No spark on the spark plug with either during vigorous cranking. But I had sensed that the engine wanted to start upon turning off the ignition. With a plug grounded on the block, it does not spark on turnover but sparks just once as the ignition is switched off. We--my neighbor has enlisted--tried it a couple of times with the same result. Is this diagnostic? As it happens, I discovered years ago that my distributor is 180 degrees out and have never fixed that. The car is negative ground.

Fix the 180 out of the dizzy first. It’s very easy!

 

[Bob_Spidell]

I've been slow on the uptake for this; usually, people usually pose Pertronix questions while they're installing. Pertronix, unlike points, switches current to the coil 'upstream' of the coil, unlike points, which switch current to ground (through the distributor). Because of this, many/most just run a permanent ground from the coil to the engine or chassis; I chose to retain the 'anti-theft' aspect by switching terminals on the cutoff switch. With points, you should see battery voltage, or close to it, at the coil 'SW' side to a ground when the key is in the run or start position; since the Pertronix switches current there may or may not be voltage; I have no idea how much since I don't know the internal resistance of an Ignitor. To my knowledge, no Big Healeys employ a ballast resistor--neither my BN2 or BJ8 have them--but they will reduce voltage/current to the coil when running (full voltage for starting).

Writing this gave my a thought, though: Check the thin, unshielded wire from the distributor points plate to the body of the distributor. Not sure what role this plays with a Pertronix--a ground reference, maybe--but, regardless, it should be in good shape.

 

[RDKeysor]

As I reported, I had only 8 volts at the positive (SW) wire on the coil, key on, using a multimeter versus 12 volts at the battery. I'll double check what I assume is the ground wire Yoda refers to in his post. I long for a way to test my Pertronix, which I now feel has failed. Another responder also suggested that I address fact that my distributor is 180 degrees away from the proper orientation. I will consider doing that. I am also getting, to my surprise, material about the Pertronix devices on You Tube. One of our trusted experts at the St. Johns Austin Healey Club here in the Jacksonville, FL, area has recommended replacing the distributor, etc. My BN7 is a very nice car and a great driver, but a review of the receipts I've kept in 11 years of ownership tell me it is a money pit.

 

[Patrick67BJ8]

As I reported, I had only 8 volts at the positive (SW) wire on the coil, key on, using a multimeter versus 12 volts at the battery. I'll double check what I assume is the ground wire Yoda refers to in his post. I long for a way to test my Pertronix, which I now feel has failed. Another responder also suggested that I address fact that my distributor is 180 degrees away from the proper orientation. I will consider doing that. I am also getting, to my surprise, material about the Pertronix devices on You Tube. One of our trusted experts at the St. Johns Austin Healey Club here in the Jacksonville, FL, area has recommended replacing the distributor, etc. My BN7 is a very nice car and a great driver, but a review of the receipts I've kept in 11 years of ownership tell me it is a money pit.

 

[Bob_Spidell]

If you have stranded copper secondary wires consider them; the Roadkill guys had exactly the same symptoms running various electronic ignitions on an old Chevy with copper wires. If you're running resistor plugs one or more could have gone bad; if you have an AM radio nearby tune between stations and you'll hear the plugs firing.