Okay..Joe, How does it work?

[skyguy59]

I decided to pop the flywheel off of my new to me 72 100hp Johnnie to look underneath. Figured I would check the condition of everything and clean the distributor rotor and cap. (It's an airplane thing..the find it down here not up there thought process). Anyway, I go to clean the cap and rotor and there is one brass "lug" on the rotor where the spark would jump from the rotor to the cap & wire going to the plug. There is no lug or terminal or carbon brush to get the spark from the coil to the rotor and no lugs inside the cap to get the spark from the rotor to the plug wire. Exactly how does this cap and rotor system work? <br /><br />Thanks in Advance<br /><br />Russ In S. Texas

 

[Joe Reeves]

Re: Okay..Joe, How does it work?

Coil wire leads to a brass contact at the inner portion of the distributor cap. The spark jumps from that contact to the brass inner ring on the rotor. That inner ring on the rotor is in direct contact with the brass lug on the rotor. The spark jumps from that lug to the pertinent brass contact on the distributor cap that leads to whatever spark plug should be fired at that particular time.

 

[skyguy59]

Re: Okay..Joe, How does it work?

Are you saying the spark jumps through the black plastic? The only brass contact visible is on the rotor.<br /><br />Russ In Texas

 

[Joe Reeves]

Re: Okay..Joe, How does it work?

Excamine the distributor cap very closely! Connect a ohm meter lead to the female threaded terminal of the cap, then find the brass portion inside the cap which will complete the circuit. Nothing is to jump through that plastic material.