MTFCA Forum

Puzzled by commutator problem Normally on Model T’s I find top dead center on number one piston. Then adjust spark advance on steering column 3 pegs down and adjust commutator to fire. On this non starter car, number one fires at top dead center but moving the commutator back and forth by the lever on the steering column does not turn it off! It continues to fire. I have removed commutator and wiped it clean. I know it is a grounding problem I suspect buying a new commutator will solve this problem?

Likely the positive wire terminal for #1 is hitting along side the front plate, try adjusting the flag terminal end to keep it from hitting metal anywhere.

The only metal that #1 terminal should strike is the rotor

If 1 fires at any position of the crankshaft, I would agree it is a ground. However, you might try your test on another cylinder and see if it fires as it should. If so, the problem is definatly on number 1. What type commutator did you use? The problem could be internal or it could be on one of the wires, or even in the coil box.
Norm

With the commutator out and wires removed, does it still buzz? I just fixed he same problem with my Anderson timer and it did boil down to #1 contact on the timer (grounding on the case). BTW, just past TDC on compresson stroke.

Sometimes small pieces of metal, get stuck between the metal case & insulating ring connection. Give the timer a good cleaning & check with a meter to see if you have a connection between the metal housing & the insulating ring number 1 connection. If you have a connection ,clean it again.

I would suggest you check for "slop" in the ends of the wire that runs from the steering column to the "commutator.' In the scenario you describe, I can see where everything electrical is working correctly, but moving the lever doesn't immediately move the commutator. This would show up in both directions. If there's slop at either end, your test could be showing a false reading. I've seen posts on the Forum where folks welded up the hole in the little lever on the steering column and then re-drilled the hole to the correct size. I suppose something like that could be done at the other end as well.