Can a Farmall B jump time

Cory Schmidt

Well-known Member
The B we have is usually a turn of the crank and its running. One day we gave it a work out by putting it on the corn sheller for a few hours. We let it cool down some, and parked it when done. Next time went to use it and crank and crank and get a shot gun blast like its 180 out. We got another tractor going to do the task.

Wanted to move it again, lets try dragging it. Spin and spin then bang. I almost was shot by the rain flapper on the pulling tractor (the cap popped off and came down inches away!!!).

So what could be the issue. Mag still turns and in the right direction and plug wires in right place.
 
if it was running good when parked , I would be inspecting the mag cap for moisture , carbon track or crack. any thing can happen... maybe the little gears in the mag are bad, as in worn out and jumped. why don't you get number one cyl. at TDC on compression and check where the rotor is pointing. if its not pointing to number one plug wire Houston we have a problem. simple to do and will answer your question.
 
Anything is possible, but my first thought would be moisture in the "distributor" cap or a cracked cap causing "crossfiring.

Take a look at that, if nothing there, it's easy enough to roughly check the timing (with "kill switch" OFF), remove #1 sparkplug, hold finger OVER the hole while a helper slowly (manually) cranks the engine.

You will feel air leaving the hole as the engine comes up on #1 TDC on the compression stroke, as piston reaches TDC, air flow will stop, and mag should "impulse".

Check that rotor points to the #1 high-tension terminal at this point.

To be more exact, remove cover under flywheel and verify that timing marks are lines uo, or at least very close.

If it has, in fact, "jumped time", post back.
 
Probably has stripped a gear on the mag drive. Make a mark on the body where the wire goes to the plug. Then remove the cap and watch where the rotor stops before the impulse it should be where the mark is. If it is not where the mark is the mag gear has stripped some teeth. That gear must be in time with the cam gear or the mag will not fire on compression. There are timing dots on that gear and they must be lined with the marks on the cam gear or the mag just will not be in time.
 
ok so we worked on another tractor near by it and left the plug wrench on the hood of the B. I forgot to grab the wrench when done with other.

I had time when I went back for the wrench so I pulled the 1st plug and spun it over to compression, I couldn't see the TDC pointer (to dark in that area)...so I cranked it till the mag just snapped. double checked the plug wire locations and #1 was still ahead of the rotor. Ok I tried putting all the wires back one port on the cap. hit the switch grabbed crank and tractor fired right off and ran great.

Now to figure out if something is actually wrong or if someone or something messed with the wires when parked out back. Thanks for the ideas to check on
 
They can run with some teeth missing. I service on that made a huge noise when running and that was the problem enough of the teeth were still there to keep it in time lucky the cam was ok. If you do pull the mag gear make a mark so you get it back the same so you don't get the mag out of time.
 

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