Hey All- came across a new one today and im looking for any insight. 1926 T rebuilt motor/transmission/and mag. Car was running very well on mag. Wow nothing better than a new motor with mag. Then a few weeks later it started running poorly (high speed miss) on battery. Really---battery? Right after being started I have to switch fairly quick to mag to keep it running smooth. Couple things we have done- cleaned plugs, rebuilt coil box (phenolic), new wires, cleaned ( switched to a known good) timer , load tested and swapped batteries (6 volt and tried 12v),disconnected the starter and the generator, pulled wires off the key switch and ran a separate wire from the battery though a toggle switch to the coil box ,swapped in known good coils ( Coilman is amazing--love those coils) when swapping parts if no change the original parts were put back in.I am not sure what direction to look next. Its very odd. any ideas or direction would be great. We are 4 guys who have 7 Ts among us and drive all of them a lot (so they break a lot and we fix them a lot) and we are at a standstill on this one.......
We have a 1914 with no magnets so we only have a battery to power our coils. The car doesn't have a starter. We use a small 6V sealed battery (off of a childs sidewalk car) to run it. I charge the battery with a small charger (an old calculator charger). Yesterday I charged the battery which was new in 2014. I also charged a back up battery that was from 2010. The car had been missing a little on the recent trips we've made. We thought it might be coils or timer. Checked both and no problems found. The topic of switching to the "plastic wood" was brought up. I have seen wood that showed evidence of tracking from an arc but have not looked on this box yet. Today, we drove about 45 miles north to an engine show. On the way up, when we pulled the exhaust cutout on, you could hear it missing slightly. We thought the timer needed cleaning. I cleaned the timer while we were at the show. We left the show and the further we drove the more it was stumbling. Finally, it got worse and quit completely. I switched to the other battery and it started running flawlessly. I haven't checked the first battery yet to see the condition of it but I'd say it is dead. I still want to install the plastic wood to see if there is any improvement.
Just a guess...check the ignition switch.
thanks vern- we ran a wire from the battery through a toggle switch to the bottom of the coil box to bypass the switch and no change. Very good suggestion though
I had a similar experience as Verne Shirk. The battery voltage seemed fine. I just switched the battery because I had another and it started running great again. Then just to see what was going on I put a voltmeter on the battery. It was dropping to 3V under load on the first battery.
Did you check the ground connection of the battery and the frame??
To do this right connect a Volt meter between the battery out put ( not the wire connection) and the frame. When starting the car you should read no tension on the Volt meter if there is you have a bad ground.
I think your trouble might be in your timer since when running on battery the entire accuracy of spark timing is determined by the timer alone but when running on magneto even a pretty bad timer can sometimes run ok on magneto since the timer only selects which magneto pulse you are going to use to fire the cylinder while the magneto determines the exact spark timing. Having the timer get way off from correct inter-cylinder time is a phenomenon that most often happens using an Anderson type slap timer since the individual contacts can come loose and move.
Thanks John- that's where we are moving to next again as we go through everything-