Setting timing on U with KEF engine

Hello,

I'm working on a UTU that has the KEF engine with magento.

The manual I have is actually for the newer 283 engine with the distributor, but I figured some of the things would be the same as far as setting the timing from top dead center.

The book shows there should be a mark on the flywheel that shows cylinder #1 at TDC. I have rotated the tractor over probably 50 times and cleaned it with scotchbrite pad and cannot find any markings on the flywheel. The only thing there are 3 holes drilled thru. They are probably about 3/8" diameter. Two are close together, and the third is separate.


I finally took the valve cover off and watched the valves to determine when cylinder #1 was at TDC. I pulled the spark plug and stuck a wire down there to feel for the piston at its highest point to confirm. I made a mark on the flywheel at this position.

Now is where I get confused with where and how to set the mag before putting it on the tractor. The slotted part on the tractor doesn't seem to be in the correct orientation for when the mag is firing on position #1. As you rotate the mag, you can feel it start to have tension, and then its another 1/4 turn before it actually fires. So if I set the mag to the same position as the slot on the tractor, the mag will fire after TDC.

Can anybody offer any help on this?[/code]

The only way you will know for sure where you are at is to install the mag, ground the "kill" terminal if the mag has one, and/or ground the sparkplug wires so there's NO possibility of the engine firing early, resulting in a "kickback", then slowly rotate the crank two turns 'til it's back and #1 TDC, noting when the impulse trips, then adjust the mag position or mag drive accordingly to get it to trip at or just after TDC, NEVER before.

After making an adjustment, repeat the "crank it two turns" procedure 'yil you get spark timing exact.

The timing marks are always tough to see. Should read DC 1-4 and 2-3. I often use emery
cloth to find mark. Remember you have to lesd mag so it will hit on # 1

Thanks guys. I've had 3 people look at it and nobody can see any timing marks on the flywheel. Is there any chance that it wouldn't have markings? Maybe an aftermarket flywheel or something? We cleaned it up real good with scotchbrite, and there is just nothing there.

The mag is a Fairbanks Morse RV4B. I'm assuming the little stud on the bottom is where the ignition switch wire goes? And then the other side of the switch is just grounded at the mounting point up under the dash?

The marks will be there. They may not be on side but back of flywheel. Original mag would
be a FM 4 BK4. Shop manual says crank motor over until intake valve closes. With hand crank
, crank motor over 1/2 revolution. At this time your piston is at TDC. You should see some
mark or make your own. Mark 1 1/2 inches past TDC. This is where your mag should trip. I
usually leave spark plug out and watch for spark. If timed correctly on cam to mag your
magneto coupling should be straight across. If all is inline and mag is timed past TDC it
cannot backfire. Feel free to email or I can be reached at 12045228456.

So how far down would the top of the piston be from TDC when the mag trips?

I think you probably solved the problem if the mark is supposed to be 1.5" past TDC. I was trying to make it fire right at TDC, and the coupling was at a 45 degree angle. So turning over until its horizontal would make sense too.

Thanks for your help!

One thing nobody said was that it is possible to mount the flywheel 180 degrees off from TDC. Your timing marks are probably on there, just on the other side of the flywheel from where you need to see them.

Another thing: it sounded like you were trying to make some other than original magneto work: Be sure your replacement has the same advance built into the coupling as the original. There are guys out there that have the books to tell you what degrees of advance you need. As soon as the engine gets above about 200 rpm. the impulse goes to full advance and stays there, so you need the correct amount of advance.

If flywheel was out 180 degrees you would still get DC 2 3

I'm pretty sure there aren't any marks on my flywheel. I've got it really cleaned with scotchbrite pad, and have had 3 different people look at it with a flash light as I rotate the engine over by hand really slowly.

The only thing on there are two holes in one place, and then another single hole a few degrees later.

I took the valve cover off and watched the valves to find TDC, and made my own mark. So if there was a mark, it would be in the same area as the mark I made, and there is nothing!

This tractor must have been made on a Monday morning...

Quite correct. Not a big deal if you have a distribuitor, but with a magneto, the coupling flange will be off (90 degrees, I think) and also the rotor button won't be at the correct position to fire #1.

I didn't see anyone mention to turn the
mag backwards to line up on number one
spark so you don't fight the impulse
and get good alignment before
installing.

Heres my 1940 UTU MM that was converted back to a magneto from a distributor...I had a friend help me thats
pretty good timing tractors......We never even looked at the flywheel...We just pulled the valve cover and got it
on #1 TDC and slapped the mag on ready to fire #1..

It still had the starter so we used it to start it the U the first few times in case in case the timing was off
some.......We moved the mag very little from the original setting and now I start it with the hand crank..We did a
21-32 Twin City the same day but used the flywheel mark on it and pretty much nailed it..It was great to hear
these 2 tractors come back to life..

Thank you guys for all the suggestions!

I live about 3 hours away from where the tractor is, so the next time I head back that way I'll have a little better idea of where to start with the timing on this U.

I had it firing at TDC, but now I know that I need to set it to fire before TDC. Hopefully that will let me get it running at least. Then I can rotate the mag in the slots to fine tune it.

I appreciate all your help.

If you set it to fire before tdc, I would think it would tear your arm off if your hand starting it. As you turn it over by hand, is the impulse engaging? As you turn, the mag will stop turning, turn engine some more, & the impulse will snap to number 1 to fire your plug. It's been a while since I did this.