Regular mag, how much spark?

fixerupper

Well-known Member
I have a IH mag on a Regular that jumps a thin blue spark 3/16" sometimes, 1/8" dependably, is this about right for one of these girls. I had the mag apart, replaced the bad armature with an armature from another IH mag, cleaned up the commutator and points and had the magnet charged. I can get the tractor to half-heartedly pop a few times but that's about it. I can choke it enough to get gas to run out of the carb so that end of the deal seems to be working, but when I pull a plug it doesn't seem wet. What are some of the characteristics to look for on one of these old girls? I'm not real proficient at working on that goofy carburetor it has but it's clean and seems to get gas to the manifold. The compression is plenty good when I crank it as my aching arm will attest. LOL Jim
 
Jim, Should have spark that could jump 1/4". Are the primer cups closed? Does not take much to flood a Regular. Most of mine will only take half crank with choke on. How have you set your timming? Mag should snap at TDC. There is a sweet spot where they like to be. when you get it right most will take 1 crank choke and start on the second crank. How many turns have you opened the carb. main jet? The knob on top of the carb. oldiron29
 
The mag snaps at TDC or maybe 1/2 degree late with the advance just above shutoff. I'll check the primer cups tomorrow. Knob is cranked probably two turns, I've been playing with it so I'm not sure where it's at exactly . Where should it be? My I&T manual is about as useful as toilet paper when it comes to carb adjustment and timing. I do have a repro owners manual and it is a little more helpful with timing but not much. What could cause the weaker spark? Armature? Points were removed and cleaned and look good. As I understand the coil is in the armature and a rebuilt is in the $150 range if I remember right. My first instinct tells me it acts like weak spark. Jim
 
Yep, either the coil, condenser or both are bad. With a good coil the spark will jump a 1/4 to 1/2" gap easily.

I assume you have the E4A mag, you are right, both the coil and condenser are built into the armature. Only option is to find a good used one or spend $150 for a new rewound coil.
 
wasn't that mag, one that had a built in (gap)? so it wouldn't carbon track if the plug wires were off? making the gap not jump very far. stumper
 
What are the plugs gapped at? The spark will jump the shortest distance and 3/16 inch is 0.188 inches - much more than the typical plug gap.

Try Autolite 3077 plugs. They look wierd but work well in the "F-Series" tractors. My guess is that spark is not your problem. My 10-20 runs just fine with a weak E4A mag.

These old tractors can be frustrating but you will be grinning eat-to-ear when she runs!
 
If the plugs aren't getting wet when flooded, may be a small intake leak.
If pull starting doesn't work I would check the manifold gaskets.
I had a 36 F20 that would get "can-tank-erous" on starting, but only if there were people watching me crank it, everyone would finally walk away, and it would start on the first pull.
I would get it flooded ( very easy to do) pull it a few feet, pop the clutch and it would start & run like a watch.
I agree it sounds like a weakening coil in the mag. The point gap is tricky to get set right. File your points to perfectly flat on base side and just a bit of roundness on the top, install them & use magnification and get them to where they just touch in the very center. An old trick I learned from a senior mechanic.
 
I have the mag back on the bench. Gonna pull the points back out and do as you say. Just as well try the simple stuff first. The owner's manual says to file to a slight point too. Lots of good suggestions from you guys.

On a side note, this Regular is on rubber with 28" rims. The tires aren't good at all so I got some new ones. I have a new tire changer bought from a dealer who claims to know about big wagon tires and changers so this changer is one he recommended for the bigger tougher tires. Thought I'd see of the bead breaker on the new changer would break the beads on these old tires so I rolled one up to the changer and by golly it did the job. It struggled and didn't do it on the first push but after I'd rotateded the tire a little bit four times it pushed the bead in. A pound of rust fell out of it. Getting the tire off the rim still has to be done the old fashioned way but at least I didn't have to beat my brains out breaking the bead. Jim
 

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