Rich in NJ
Member
Well, a few days ago, I had thought that my tune-up issues were over. I had been battling what I had thought was a too-thick distributor cap gasket on my '57 Powermaster. Unfortunately, after re-installing the original gasket (0.063" (rubber) vs. 0.077 (cork)) and hitting the start button, I was again faced with a broken rotor. Having no other rotors around (and being my usual cheapskate self), I broke out the epoxy and a day later had a working rotor. This time, prior to going for a start, I took one of my old distributor caps and sawed out a section with a coping saw. This modified cap was installed and allowed me to see what was really going on inside. It turned out that the rotor itself was too long, and not too high up as I had originally thought. I proved this by swapping out the rotor from my '63 4000; as I had also tuned it up at the same time. The Powermaster rotor barely squeaked by. In fact it managed to shave off a tiny bit of epoxy in the process. The 4000 rotor had at least a 0.020" gap. At last I had found the real reason why I was failing so many rotors. I promptly opened up the gap by taking a file to the end of the rotor. So, the real question is this: what should the inner (circular) dimension be within the distributor cap? I can easily mike this up and see for myself, but what is the correct spec? The other just-as-important question is this: what should the gap be between the tip of the rotor and the inner face of the four contacts within the distributor cap? I am quite inclined to fabricate some sort of fixture that would allow me to check - and possibly correct any rotor that I purchase from now on.