Distributor cap to rotor clearance

Rudolph

Rudolph

Senior Member
I have got a few reproduction caps for the crab distributor and a couple bob drake rotors, the rotors collide with the terminals on the cap, made the mistake of trying to run one and busted the rotor and cap, non of them turn freely, tried 3 different distributors.

I understand they use to run basically "0" clearance? I have had to fire the rotors till I can turn the distributor
 
Sorry, I cant give you a spec, but "zero" would certainly not be correct. spark intensify s with a gap. The beauty of the crab dizzy is you can set it up off the motor to know its all correct before you mount it. While it would be a challenge to measure with the cap on, you could at least know that it turns with out crashing. Model A fords call for a .025 gap between rotor and cap terminals, however on those you can remove the cover and see exactly whats happening and measure it.
 
Do you have the correct rotors? I changed from rabbit ear distributor cap to crab and it required the corresponding rotor.
 
Howdy, Do you have a 42-44 cap. That would be the one with external terminals and a one piece design. If you do then you need a 42-44 rotor. the later 46-48 cap was a two piece design. The terminals are located under the cover cap. I think this type was made to prevent water fouling when driving in wet conditions. The rotors are not interchangeable between the early and late.
 
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