I took the roller timer out today to see what I could find while I wait for the new one. I had changed rollers yesterday with another that was in the parts can. I lubed it up and put it together and started the T and it ran real crappy. I shut it off. Today I took the commutator off and saw that it was a little bumpy. I know that a lathe is the best way to true them up but I don't have one and I am 70 miles from one. I had to come up with a different idea. I do a little wood working and have a little assortment of sanding drums that go on a drill or drill press. One of them fit right into the hole in the commutator. It didn't take long with the drill to smooth out the circumference of the comm.
One note if you try this. DON'T sand the insulated area unless it needs it. On mine I just needed to smooth out the metal contact which stuck out a little above the rest. Turned out pretty good and it started right up and ran pretty nice. Something still wrong because the motor still has a vibration that I can't get rid of. Coils all seem to be firing good. Any suggestions?
As to your motor vibration, try running the engine with the fan belt off. Some fan blades are really out of balance and can cause some pretty good vibrations. Also, check your motor mounts for cracks and be sure the wooden side blocks and side bolts are in place next to your motor mounts.
A very interesting an ingenious way to smooth out the inside of the commutator...BUT...I have to wonder...
Much has been written about the importance of having the cover accurately centered on the camshaft.
So my thought would be : could smoothing the inside of the cover "by hand" lead to an inside surface that is ever so slightly "off center" enough to cause less than desirable engine performance. From the literature, it appears extremely important for the commutator (inside surface) to be absolutely centered with the cam.
Stan Howe posted this a couple/few years ago:
Mount some kind of a motor, Dremel tool, etc square with the bottom of a board so the sanding drum sticks up through a hole and will square up with the contacts and insulation. On the top of the board mount a piece of 1/4 inch or thinner plywood with a V cut in it. Make one end solid and the other end adjustable. Put the timer face down and rotate it with the sanding drum cutting the contacts and insulation. Take a little off at a time, move the V a little closer to the drum each time and it will clean up a timer faster and just as good as a cut on a lathe will. I gave mine to a friend as I no longer needed it. Mine was made from an old 1725 rpm free motor with a 1/4 inch adapter on the end of the shaft and a cheap sanding drum on it. Cost about two bucks to make and I used it for 30 years. Now I would do it the same way. I've tried to do them on a lathe and it is a real pain. This way takes the outer edge of the timer as the reference and can be adjusted a few thousandths at a time.
Setting up to turn the contact surfaces in the 4-jaw, I found the timer body to be about .012" out of round. Can I assume this means the contacts may be as much as .006 to .012" off center when installed ? Then there's the fit up of the roller and the working tolerance of the timer to gear cover fit.
How much off center run-out is allowable before the variance affects performance ?
The timer is a little forgiving. The roller is spring loaded . Imho your timer is fine. The housing is stamped sheet metal, so a little out of round should be expected. The roller track is machined so it should be true.
You can easily check that all cylinders are working by stopping 2 cylinder at a time. With the engine set a fast idle, it should still run OK if 2 cylinders are 'de-activated'.
To do this, run the engine at a fast idle with the coil box lid removed.
First stop cylinders 2 and 3 by pressing on the points' cushion springs for those cylinders (the two middle coils). Then do the same for the end coils to stop cylinders 1 and 4. If any cylinder is not working properly, you will get a 1-cylinder engine!
Thanks Royce and the rest of you boys for posting your comments here. I'll check your ideas out as far as the vibration goes. Good idea there by Stan. I can see how that would work. The sanding drum that I used just barely fit into the inside of the timer so it did a good job, not perfect but certainly better than it was.
I wouldn't recommend this method for too many re-do's because no doubt you could put the inside out of round and perhaps off center as Dave pointed out, but for a quick touch up it would work fine.
I will be back to it on Friday so will post if I find anything concerning the vibration. Again, thanks for sharing.
I think I will start a new thread for the vibration issue because I have gone off topic with the heading. Look for "Vibration in the Motor Issue" as a new thread tittle.