F-20 miss on #2

1936 f-20 been running fine, starts fine, but today it started running rough. is not firing cyl#2. pulled plug, and its firing, even swapped plugs and wires around, and its always #2 no matter what plug is in it. pulled valve cover and everything seems to be working fine. what gives all of a sudden? was running great and i decided to clean plugs, and when i put em back in, has a miss. at this rate it is gonna be for sale real soon!

What kind of mag?? Have you checked the contact inside the cap for #2 cylinder for a crack?? How about where you plug the wires into the cap on the outside. Any chance that one end of the wire could have pulled off and still remains in #2 position inside the cap, thus causing a poor connection?? Got me wondering also. Seems strange that it happened all at once. jim

Bdunegan,
You have violated the number one rule; "WAS RUNNING GREAT AND I DECIDED TO CLAN PLUGS" If it wasn't broke what were you fixing??? Go back and check everything you "FIXED", continuity of wires, mag cap, etc.

have got it narrowed down to faulty wires and maybe plug. can ground out each plug while running and all has great fire(will jump 1/4" gap when grounded across to head) except #2. can pull wire from mag and use screwdriver to ground cap contact, and still great fire!. plug wire back on, and ground at sparkplug end, and really have to work to get any spark at all. hoping just a good tune up fixes it. lord knows when it has had one by looking at wires. also has champion plugs in it now , but what is the same number for autolites? probably switch and do a tune up and see what happens. the reason i decided to clean plugs, it has only been run maybe 30 minutes in last three years till i got it. i was just checking everything out. should have left it alone, because it is SUNDAY.

Make sure that you use WIRE core plug wires, the carbon core resistance wires tend to not work well with a mag. Get a brass brush to really clean the cap connections.

Put a set of Autolite 3077 in it. The yhave a longer, funny looking tip and will make her purr like a kitten.

Should have asked about the plugs. My M did the same thing with NEW CHAMPIONS and had to switch. Champion does not seem to be what it used to be (in fact none of us are) LOL. Shut it off one day and the next day it was missing. jim

changed plugs to autolite 3077s today, changed wires, gets real good fire on #2 now, and is firing the plug(took out plug and hooked wire to it and started tractor). pretty blue fire jumping plug gap. put plug back in, and will not fire that cylinder at all. with valve cover off, everything looks to be working fine, but still a miss. at this rate, it will be for sale shortly. i bought it and it ran fine, drove it around, and run great till yesterday. now a miss. i am not mechanic enough to do a tear down on this thing, so will probably list it shortly. anyone interested can view pics in tractor photos under bdunegan, 1936 farmall f-20.

Heavens. Don't give up that easy.

If you checked your valve clearances on number 2 and the valve operates freely, you have a spark problem. You tried new plugs and new wires and they will spark everywhere except 2. That leaves something in the mag. Now all the other plugs are firing, so you have spark to the distributor gear. From here, I would say that it's in the cap. Any buddies have a spare?

I took my mag a part four times this spring before it would start. Finally ran it on the bench with a cordless drill before it would fire consisitently.

havent checked valve clearance yet(really dont know how on this one) but all valves seem to be working good as checked with cover off running. all springs in line and no sign of breaks. everything oiling well. really clean under cover. very minimal sludge.#2 wire is firing great on plug as checked. still starts on 2nd crank! was thinking maybe rings, but NO smoke at all while idleing and open up full throttle, still no smoke! very minimal oil on plug after runs awhile. mag has strong spark on all wires. when grounded out while running, will change engine sound on all but #2. was running fine until dummy me decided to check plugs and clean them. cant believe it would do this all at once. can remove #2 plug and crank, and compression seems strong! (will blow my thumb off hole! so really cant figure valves sticking, but then there is reality in the form of no firing cylinder on good ole #2. checked spark at cap every tower, and wire at every plug end, and every plug to verify firing. but when #2 plug is in, still dead cylinder! I aint giving up yet, just puzzled and aggravated. Thanks for all the input so far. maybe we can figure this out eventually!

By chance didnt get the wires mixes up did you? What happens if youy move one of the wires to another cylinder?

have wires on correctly I think. starting at top right on cap should be #1, below it #3 to the left #4 up #2. if i swap wires around the wires still fire, and will fire #2 plug, but wont fire the cylinder. all wires firing great, all firing plugs. even #2 is firing plug. just wont fire the cylinder. Possibly a blown or leaking intake at #2 port? just guessing!

decided to not give up just yet, and checked valves one more time. guess what? when checked again according to where it should be lose(followed guides on this sight on how to check) it was tight! losened off some, and it started hitting on good ole #2. set it to where it ran the smoothest and left it! still runs a tad bit rough on idle, but under a load, smooths right out. dont miss at idle, just rough. new carb rebuild will probably be soon. at least i drove it around the yard some more!!! shut it down, and let it set for a few minutes, and started on FIRST tug of crank!!! maybe hope after all. Thanks so much everyone for the responses. without them i wouldnt have known where to go next!!!