I have recently completed an engine rebuild on my 1959 TR3A. Prior to rebuild I installed Pertronix electronic distributor and car ran fine. My current dilemma is the engine will turn over but not start. While troubleshooting this, coil lead was removed from center of distributor cap and held about 1/2” from center connector of distributor cap. With ignition key on and solenoid button (under hood) pushed, car started immediately and ran smoothly! I inserted coil lead to distributor, engine continued to run strongly; turned key off, tried to restart leaving coil lead inserted in distributor - engine just turns over without firing. Remove coil lead as before, push start and engine starts instantly, runs smooth and strong. I have tried 3 different distributor caps, 3 different rotor arms, 2 different sets of ignition/coil leads, two different coils (40KV), brand new battery (800 cranking amps), rechecked static timing, two different sets of plugs (one set gapped at 0.035” another gapped at ~0.047”) - rationale gap should be higher with Pertonix. I have even attempted starting in the dark looking for shorts tracking anywhere, with no success. Also replaced module in Pertronix with new module. BTW engine starts every time (with coil lead out) after various changes described above in trying to isolate problem. Compression on all 4 cylinders is ~170psi; valve clearances confirmed. One last comment is car had TR4A carburetor linkage with HS6 SU’s with “Capstat Jets” when I purchased it 32 years ago. As part of the rebuild, I have replaced the carbs with new HS6 SU’s. I have yet to bypass ignition switch to eliminate it - ? Voltage drop in circuitry to switch...? Any suggestions would be greatly appreciated. Thank you. David

Sounds like the ignition circuit is grounded some place. Is the car positive or negative ground? How is the coil wired to the distributor, i.e + to switch, - to distributor (if negative ground)?



Edited 1 time(s). Last edit at 2019-01-26 06:24 PM by andy303.

Another thought would be to reinstall the old points distributor and see if it behaves the same. If it starts and runs as normal you know where the problem lies.

Attached is the Pertronix troubleshooting guide. Your thought about voltage drop may be correct. If there is not sufficient voltage the Pertronix will not fire.



Edited 1 time(s). Last edit at 2019-01-26 07:17 PM by andy303.

Hi Andy thanks for responding! The starting problem has been ongoing, with other members kindly contributing; the symptoms have varied with the above post the latest finding. While engine was being done car was repainted. That’s compounded everything due to ground issues as well as other wiring issues having to be resolved. Prior to restoration, I had replaced voltage regulator with solid-state regulator (recommended by another member) and points distributor with Pertronix distributor - with car running well with those changes (solid state VR and Pertonix electronic distributor). I naively assumed getting new engine to run would be straightforward. I have tried points distributor with no success. That said I am now going to reinstall original voltage regulator and points distributor and get car running with those. Coil is wired to distributor with 12V applied to +ve terminal of coil through ignition switch. Car is negative ground. Engine rebuild was decided upon due to oil in H2O, compression readings ranging from 109psi-118psi, wear marks observed on crank and wet liners flush with block face at cylinder #’s 3 and 4. I’ve upgraded to 87mm pistons and liners. BTW, I bypassed ignition switch with jumper yesterday with no success. I will post as to how things respond. Incidentally, I assumed Pertronix was working when engine started instantly and ran strong with no missing, despite coil lead displaced ~1” from insert position on distributor.

That's the bizarre part. The Pertronix is said to be sensitive to available voltage, which drops during cranking. That seems to fit your symptoms. Also sensitive to poor grounds. You could run the resistance and voltage checks listed in the troubleshooting guide above.

when you hold the coil lead away from the cap, you are intensifying the spark- it gives more jolt at the plugs and starts the car.

Yeah, that's an old-timers trick for getting fouled plugs to light off sometimes.

I would try it using the correct .025" gap (the .032 in the workshop manual was revised early on); but it doesn't sound like it will help.

FWIW, when I ran a Pertronix module, I had a battery failure such that the Pertronix wouldn't fire, but the engine would crank! They are very definitely voltage sensitive. Converting back to points got me a few more starts before the battery died completely.

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Randall
56 TR3 TS13571L Once and future daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild