Steve brings up a good point here, and one that I’ve been monitoring around here for many years now. Although the burn mark on the OP terminal clearly shows a phasing issue, the rotor air gap won’t have any measurable effect due to that alone….
However, as Steve mentioned, that air gap is or has gotten to be a very big thing in the last 30 years with these rotors. If you want a treat, do as he says and take a cutoff wheel to a cap. Cut a window in the side. Then go buy about 4 different rotors and install them on the distributor and look at the air gap between the rotor tip and the cap terminal…all over the place.
Back in the days of Sun ignition scopes this “air gap” distance was actually a test checked with an oscilloscope.. the bigger the gap= the more firing voltage was required and seen on the scope. Somewhere over the years these rotor tips kept shrinking until some of these air gaps are near close to 1/4”. Now the ol HEI will quite easily jump that gap but they’re not supposed to be that way. These manufacturers are getting awful loose with the quality control here lately.
Given the fact that different manufacturers make replacement caps, and we all understand that each cap mfg is not made in the exact same size mold, I think we can figure out there needs to be some rub room here on the rotor tip length. That way if you mix and match disastrous results don’t happen to rip the tip off a rotor. I would think these cap terminals should all be within a few thousandths of each other so that the rotors could be fairly close….
But this stuff for the last 15 years for sure has been all over the map. So I think they’ve been cutting the rotor tip back to compensate.
Ideally you’d want the rotor tip as close as practical without whacking any terminals. Anything closer than .100 is not going to make any real difference but 1/4” is just dumb.
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