Backfires and will not start '53 UB

MnBoy

Member
I have been unable to start the UB since I "fixed" the distributor by installing an electronic ignition. Wasn't running great before all the new stuff was added. New "hot" coil, plugs, wires, etc, etc. I am sure that I have the distributor out of rotational position. Not sure how to proceed. All I get are tremendous backfires...complete with flames out the muffler. My wife wants advanced warning when I try to start it! Can somebody get me on the path to victory?
 
Put back to original is what I do on all mine. To backfire is timing or wires crossed. Distributor location does not matter. Can be
put in any location long as correct timing/ firing order and advance working. Was it running before the electronic update?
 
(quoted from post at 16:35:56 06/14/19) Put back to original is what I do on all mine. To backfire is timing or wires crossed. Distributor location does not matter. Can be
put in any location long as correct timing/ firing order and advance working. Was it running before the electronic update?
Yes it was running but very rough. Went from running well to poorly in a short period of time. Thanks for your input.
 
Valves also can cause issues if stuck open. Not common on a U,more on R/Z. Go back to basics. #1 intake valve closes rotate motor
1/2 revolution. Will be TDC. Rotor lines up with #1. order 1-3-4-2. Same on all. Possible cracked cap?
 
Did you have the distributor out of the block?

Position #1 cylinder at top dead center on compression stroke. Whatever plug wire the rotor points to in the cap is #1 plug. Distributor rotation is clockwise and firing order is 1-3-4-2

#1 position is normally about 1 o?clock position, but, as others have indicated, if properly oriented to #1 cylinder it can be anywhere on the rotation circle.
 
I installed an electronic ignition on my U also. Although it was timed properly with old points, when I installed electronic parts, I found I needed to rotate distributor considerably to get proper ignition timing. Start by rotating distributor clockwise, maybe five to ten degrees.
 
I find that many times if the distribuitor is properly timed to #1 cylinder, swapping The 2 wires on each side of #1 works wonders.

I forget, but the U distribuitor turns one direction and the R and Z distribuitors turn opposite. Most times I have to leave the cap off and
hit the starter to see which way it turns.
 
(quoted from post at 19:03:15 06/14/19) I find that many times if the distribuitor is properly timed to #1 cylinder, swapping The 2 wires on each side of #1 works wonders.

I forget, but the U distribuitor turns one direction and the R and Z distribuitors turn opposite. Most times I have to leave the cap off and
hit the starter to see which way it turns.
Yes, I had to double-check this. The rotor definitely turns clockwise. The firing order is 1,3,4,2. This is for sure.
 
Yes, I had the distributor out of the block. [Worked on it in my basement shop.] I did remove number one plug and fished a stiff wire in cylinder 1 to find the top of the stroke as I turned the crankshaft slowly with a pipe wrench. When it got to the top and before it started back down, I considered this top of the compression stroke. I think that when the cylinder is as high as it gets, that is the top of the compression cycle and when the plug should fire...right? Otherwise, I don't understand it correctly.
 
I am not sure how to test whether the valves are all moving correctly v stuck. I guess just look for movement when turning the crankshaft? The Dist. Cap is new, so it should be OK. Are you saying that when #1 cylinder intake valve is fully closed, if I rotate the rotor 180 degrees from that point...that will put the rotor at TDC? That will be the position for #1 wire. Sounds easy enough.
 
Open cover on left side of tractor to expose flywheel. TDC is marked on the flywheel and is to be aligned with notch in casting.
 
It is a four stroke engine, piston at the
top could be either compression or
exhaust. For it to be compression you
would have to know the valves are closed.
You may be 180 off.
 
Take valve cover off and watch second valve. When it closes rotate motor over 1/2 revolution with hand crank. This is compression stroke. Piston will be at top and tdc mark will line up on flywheel. Another method is turn motor over with finger in sparkplug hole to feel compression stroke. Bring piston to top and time to marks of flywheel. Now set your distributor to #1. Think you are timing on wrong stroke so #4 will be firing causing backfire. If you set distributor to fire on #4 it would run.
 
Thanks for the input. I bet you are right on being 180 degrees off. I may have timed it to the exhaust stroke v the compression stroke. Dumb mistake.
 
Well, I took all of the collective advice given...and thank you for it. I found the cover for the flywheel [also called a clutch
cover]. Lined up [went 3/4" past] the D.C. marking [rather obscure] on the flywheel the the notch in the casting. Considered the
rotor to be pointing at #1 cylinder wire. Aligned wires [clockwise] according to 1,3,4,2 the firing order. Started right up! I
still have some engine work to do as the muffler was belching out some pretty black smoke. I'll save that for another time.
Thanks again to all.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top