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Coil numbering?
Posted: Fri Jul 19, 2024 12:38 pm
by GoldToyBox
Family problems and health issues have kept my 1921 TT in storage for the last 3 years.
I'm trying to start it again after installing new generator and timing gears.
Something isn't right. I have fuel in the carb but not firing.
So I'm going through the ignition now.
Sitting the driver seat, which coil box is #1?
It appears that with the #1 cylinder at TDC, the coil on the left is buzzing but it's connected to #4 cylinder?
Been looking for a drawing without much luck in the Recourses pages.
It's a sunny day here on the coast and wife want to go for a ride.
Re: Coil numbering?
Posted: Fri Jul 19, 2024 1:14 pm
by JTT3
Courtesy of Randy Stevens, just FYI if your coil box is mounted on the engine 26/27 style it’s reverse of the picture of the earlier firewall mounted coil box.
Re: Coil numbering?
Posted: Fri Jul 19, 2024 1:18 pm
by Been Here Before
Re: Coil numbering?
Posted: Fri Jul 19, 2024 1:52 pm
by Steve Jelf
A lot of timers have numbers by the terminals. The black wire (#1) goes to coil #1.
Re: Coil numbering?
Posted: Fri Jul 19, 2024 2:29 pm
by Norman Kling
Piston 4 and 1 are both on top center at the same time, but you want the spark to come when it is at top on compression stroke. Both valves would be closed at the same time when the spark comes. If the exhaust valve is open it is the exhaust cycle and no spark
Norm
Re: Coil numbering?
Posted: Fri Jul 19, 2024 2:40 pm
by 67pontiac
It's possible the camshaft timing gear is installed 180 degrees off. If the pin hole in the end of the camshaft isn't drilled all the way through the camshaft, the timer "rotor" can only be installed one way. Number 1 and number 4 cylinders are "paired" cylinders. If the cam gear is installed 180 degrees off, the rotor will be firing number 4 cylinder when number 1 cylinder is in the firing position. If the hole in the end of the camshaft is drilled all the way through, simply re-position the rotor to fire the correct cylinder. If its not drilled all the way through, you can drill it through, or dis-assemble the engine and re-position the timing gear. I hope this helps. Kind Regards.
Re: Coil numbering?
Posted: Fri Jul 19, 2024 2:49 pm
by Jerry VanOoteghem
67pontiac wrote: ↑Fri Jul 19, 2024 2:40 pm
It's possible the camshaft timing gear is installed 180 degrees off. If the pin hole in the end of the camshaft isn't drilled all the way through the camshaft, the timer "rotor" can only be installed one way. Number 1 and number 4 cylinders are "paired" cylinders. If the cam gear is installed 180 degrees off, the rotor will be firing number 4 cylinder when number 1 cylinder is in the firing position. If the hole in the end of the camshaft is drilled all the way through, simply re-position the rotor to fire the correct cylinder. If its not drilled all the way through, you can drill it through, or dis-assemble the engine and re-position the timing gear. I hope this helps. Kind Regards.
The timing gear can't be located 180 off, either mounting position amounts to the same thing,
but the timer rotor can be, if the cam has the hole drilled through, (as you stated). If that's the case, then just turn the rotor 180 degrees to the "other" position. Ultimately, you want to be firing on the compression stroke and not the exhaust stroke.
Re: Coil numbering?
Posted: Fri Jul 19, 2024 3:18 pm
by Moxie26
Really now.... If the camshaft is drilled all the way through crank until the camshaft rotates 180° and reinstall the commutator roller/brush so that the ignition will work as intended . The same predicament had George Mills and I confused on why a Depot hack engine at a Ford dealership would not start. ..... Not only did the engine have the camshaft drilled straight through, it also had a very loose front cam bearing which added to the wobble inside the commutator.
Re: Coil numbering?
Posted: Fri Jul 19, 2024 3:45 pm
by GoldToyBox
Thanks to everyone for the information and drawings!
Pretty sure I got it figured out.
Edit:
I flopped the roller assembly under the timer cover, and it started on the first try!
Drove it down to the gas station, topped off the tank, drove wife, sister & neighbor around town.
I think I'm ready for the parade.
Thank you to every who helped.
Re: Coil numbering?
Posted: Sat Jul 20, 2024 7:20 am
by Humblej
The only way to be sure which coil is going to which cylinder is to check the actual wire at the coil and again at the timer, you may have to peel back the loom a little to see the color of the wire due to dirt and fading. Regardless of what the wiring diagrams show, there is no telling what previous owners may have done over the years.