Allis Chalmers B only Runs On Two Cylinders

Hello I am new to this site and this problem has me stumped. My uncle brought up a B for me to work on and I got it to run by cleaning and rebuilding the carb. When it was running it did not sound quite right so when it was running I took off each plug wire one at a time starting at the radiator. The one closet to the radiator is firing and so is the one closest to the drivers seat. The two in the middle will not fire. Those two both have spark, and are both getting fuel. I also cleaned up the points and set the timing. Any ideas? (This tractor has the magneto and is electric start.) THANKS

You probably have the two wires interchanged. Remember the firing order is 1243.

Paint it Green & tell everyone it's a JD B!! I'll bet you have the plug wires in the wrong order. However you should still get spark from those other two cylinders just at the wrong time. Has it had water in it & then pull started? Could be bent or broken push rods. 2 & 3 cylinders are most prone to taking on outside water. 

At first I did have the wires in the "correct" order on the cap and plugs, then I went out and started switching wires around and got it to fire on all four cylinders. Don't ask what I did because it is not in the correct order. I am going to get some new plugs and wires but right now it sounds pretty good. Thanks for all the help.

I once worked on my WD-45 when it wasn't running on all 4 cylinders.  I 1st checked to make sure the plugs were firing but I did it with the plugs out so I could watch for spark - they all fired.  And they all looked good.  After replacing the points, condenser, rotor, distributor cap, plug wires, I finally replaced the spark plugs.  Engine ran fine after that.  A mechanic later told me the plugs were not firing under pressure.  

The Allis four-cylinder engines have a firing order which is somewhat opposite of most of the world... and it's not always apparent which towers on the cap of a magneto go to which plugs... because some moron (like me) would, rather than take the time to remove the cap and rotate the rotor to the proper plug, just slap it on, figure out which one matched which cylinder, and let 'er rip... and leave the next guy to figure out what happened.

But no matter-  they'll work regardless... just so that they fire in the right ORDER.

Obviously, since you swapped the wires, and it came to life, the problem was that firing order was switched.  Perhaps it's because the rotor was assumed to turn in one direction, rather than the other... and with mags, that's not unusual.

Anyway...  I went through this routine with a great big Hercules JXLD... 331ci inline six, the engine's oilpan holds 37 quarts, and the radiator is 38" wide and 45" tall... and has a 24v starting motor, which I decided not to use, because it had a perfectly good hand crank... 

But I had a situation where the magneto decided to go on strike.  It was due for a rehab, so I took it in to my hero John Boyens, who gave it a meticulous work-over... and I finally got it reinstalled on the big Herkey... totally ignored the rotor position, because no matter WHERE you look on this monster, the firing order is NOT indicated... instead, I just took out all the plugs, left 'em hooked to wires, and set 'em on the head.  Put one plug in #1, and turned the crank 'till I had compression... then slowly went past the CLACK, and look-see'd which one sparked.  Then I swapped wires so that one landed on 1.  Then moved my plug to #2, repeated... then 3, repeated, then 4,5,and 6.  Put in all plugs, turned on the fuel, gave it a snort of ether (it'd been a while, and stepped on the crank through three clacks, and it started right up.

I love magnetos... never hafta worry about a dead battery...

The way mine is set up is number 1 post on the cap actually goes to cylinder #4 and number 4 goes to cylinder #1. I know on my farmall H that both 1 and 4 are on compression stroke at the same time so maybe this is the same. When I tore apart the magneto I made sure that the gears were matched up. My magneto has the condenser on the right so I put the teeth in the C tooth. Will get some new wires and plugs but I think it sounds pretty good as it is. I can now take off in third if I am careful an at a fast idle. It sounds a lot like this tractor on YouTube. http://www.youtube.com/watch?v=Y-DXSffkA_U
Thanks for all the help I will try and take some pics of it tomorrow. And I am sure I will have more questions.


Edited by SS_Skippy - 21 Aug 2012 at 9:12pm

Went to go take pictures and the camera was dead maybe tomorrow, does anyone know what plugs to use in this? Thanks

I get better reports on the auto lite 295.  In fact, our electrical expert, SteveNJ suggests Auto Lite only. 
Glad to hear my favorite is running well again.
Good Luck!
Bill Long

Just think... 25 years ago, that'd involve a roll of film, two trips to the photo processing shop, an envelope, a stamp, and about six weeks... 

I love it when modern technology can be used to share OLD TECH.  I just wish my cellphone had a magneto, rather'n a battery...