Despite the occasional smoke it ran great in the yard going forwards and backwards for 100 feet. As soon as I took it out on the street, for the first time, it ran fine at first but then it start to stumble and backfire from the carburetor. Finally it stalled and would fire up again but with great difficulty.
Barely manage to get it back in the yard. After a little effort I had it running again with no problem.
Iíve cleaned all the wire connections, had the coil box out and cleaned all the contacts and cleaned the timer. It does not appear to be an ignition problem
Itís seems that the trouble starts when I hit bumps and make turns. I was thinking fuel starvation but why would it be hard to start when I stop moving, at that point it should start right up as soon as fuel reaches the carburetor. I have said before that it smokes occasionally but I donít think it is fouling the plugs and it smokes when it is not moving and runs fine.
Could it be the carburetor float setting? Flooding the carburetor making it difficult to restart?
Peter: what flavor carburetor are you running? Holley, kingston, wizard or vaporizer? does it have a standard needle jet of a grouse jet(SP?) have you adjusted the mixture?
Make sure that you have plenty of gas in the gas tank. I consider a Model T to be out of gas if there is only two gallons in the tank. Less than that and it starves on turns or the slightest hill.
Also make sure no one has installed any inline fuel filters. They don't work in a gravity fuel system.
What you describe could be a float setting that's too low causing starvation under a load then it slows the bowl re-fills and it gets fuel again. That in itself wouldn't cause backfiring or hard starting because there would be enough fuel in the bowl to start. It's the backfiring and running poorly after bumps & turns that bothers me. By all means pull & check the plugs. You might get some indications from their condition. It really sounds like a loose electrical connection. Losing ignition then getting it back will definitely cause backfiring when it ignites un-burnt fuel. You have more checking to do.
Kingston L carburetor with the flapper.
That sounds like an L-4 make sure you have this jet
not this one I put one in mine and it never ran good with it.
is this a pre or post 1926 (difference in where the gas tank is mounted)
and this drawing by Martin Vowell may help