Re: Pertronix Flamethrower Dist.
Thanks Michael, for seeing my similar post in the Racing Forum and telling me about this thread. Please excuse, I'm cross posting this to both forums.
The problem that I have may be unique to just the Pertronix "HP" distributor with the Igniter II module, not a Lucas conversion with regular Igniter module. Mine is one with mechanical advance only and a top entry dizzy cap.
I installed it on my Lotus Super Seven and acquired an engine miss that seemed to be associated with the rotor cap. I tried several "blue" rotors and one "black" one. If I seat the rotor all the way on the dizzy shaft, I have an intermittent miss, most noticeable in low to mid range rpm. It occurs whether I'm running the Flame-Thrower II (0.6 ohm, high turns ratio) coil or a Lucas Sport (3 ohm, lower turns ratio) coil.
I stumbled on the fact that if I raise the position of the rotor (blue or black) on the shaft as far as I can (just 10 or 15 thou shy of going solid with the underside of the dizzy cap), the miss goes away. I don't know if the rotors are arcing to the shaft or if the distance to the Ignitor II module (taller than the old regular Ignitor module) or something else is the issue, but I wasn't crazy about the idea of having to run the rotor just barely on the dizzy shaft.
As an update, let me first say that the Pertronix customer support is great. They are very refreshingly responsive by comparison to the norm these days. After trading a few emails with an engineer there, he asked me to send the dizzy to him so he could check it out. No hassle requiring a RMA and proof of purchase, etc... just send it and he'd look at it. As luck would have it though, he was unable to get the distributor to miss on the bench. He replaced the module and rotor anyway before he sent it back to me. I got it back last Friday and tested it in the car over the weekend, resigned that I must have a weak link somewhere.
I installed and ran the dizzy just as it came out of the box, with black rotor fully seated on the shaft. I also changed spark plugs and reduced gaps from .035" to .030" before a short test drive. The miss was still there, but seemingly not as bad. I opened the pug gaps to .040" and the miss was worse. I changed to a blue rotor, fully seated on the shaft. Same result. I raised the blue rotor on the shaft so there was a good 1/16" clearance between the underside of the rotor arm and the top of the Igniter II module, and... wait for it... the miss went away again, just like before.
I then tried a trick that was suggested by Keoke here in this forum. I removed the metal spring in one of my black rotors that keeps the rotor tight on the dizzy shaft. I fully seated the rotor on the shaft using a narrow bit of vinyl tape over the top of the shaft to cause the rotor to fit tight. Wow. No more miss. I repeated the test with another rotor, this time a blue one that had caused the miss before. Again, no miss while using the rotor fully seated with metal spring removed. Just a bit of vinyl tape on the shaft to make the rotor fit tight.
I can live with that.
Cheers,