38A mag Problem_Help Clooney

~That was the mag I had in mind when you said it is only firing on side after sitting for a while. [not the friendliest of mags to work on]

~I have a pretty good idea what's wrong.... CAREFULLY remove the distributor cap [that cap is very expensive so be careful], once it's off look inside the cap at the towers where the wires hook to & you will see two little carbon brushes with springs behind them. I'm betting the brush will be stuck on the side that isn't firing. If it's stuck see if you can free it up with a drop of greaseless penetrating oil & working it with a pencil eraser end of a pencil [don't use anything that will damage it as those brushes are real hard to find]. Also look at the spark disk that the brushes ride on & remove any carbon tracking & oxidation in the brush contact area. Then check the point gap to be .015" [if not at .015" re-set as the point opening must coincide with the magnetic rotor edge gap]. Then carefully re-install the cap & try it.

~If you don't find a stuck brush post back, CAUTION: don't go in any farther without a book or asking or you will have to re-set the gear drive timing & I don't want to have to type that much if I don't have to....

Before I begin, are you aware that the two cylinder tractors with the single barrell carbs such as yours, always fire stronger at idle on the left than right cylinder???? Thats because they fire the left side, and then only 180 degrees later the right, and then there's that long 540 coast cycle in which time residual vacuum in the manifold and carb stores up a good healthy fuel charge that gets sucked in for the left cylinder.

NOW FOR THE SPARK DIFFERENCE:

1. The same points and coil and condensor fires BOTH sides, so if one terminal (top or bottom) fires better, the cause may be a problem or difference in the cap (one terminal or its distance between it and rotor tip) or rotor (it has 2 tips remember, and one may be different or have a problem or carbon etc) or individual plug or plug wire. You say you substituted plugs and wires, so if that ruled out those problems, the remaining problem areas causing a stronger spark out one terminal over the other could be a rotor (crack or corroded or carboned up tip) or cap problem like a crack or carbon path or a terminal or its location inside the plastic, only affecting one terminal and not the other.

2. Other problems which could affect one sides spark more than another, could be one cam lobe is worn more than the other (points, therefore, wouldnt open same gap each time) or a worn and slightly wobbling mag rotor shaft (therefore cam wobble) due to a bearign problem. A band aid help for that may be to widen the point gap to maybe 0.017 versus the 0.015 recommended and check the gap at each high cam lobe to see if any difference shows up.

3. To test the quality of the spark totally independant of any cap or rotor, with the cap removed, simply attach a wire to the mags steel frame and place it within 1/8 inch or so from the mags high voltage output button (where the caps spring fits) and when the mag snaps over to fire, you should see a good blue spark there.

4. You indicated each side has equal compression, so I wonder if you really mean you tested each plug and wire etc., or just mean the right doesnt seem to fire as strong????? ???? Remove each plug and with their wire atatched and the plugs steel frame against the tractor, observe if each fires about the same quality of spark, and if swapping plugs and wires makes any difference. If the cap and rotor have no problems and the cam lobes open the points approx the same for each firing, the spark quality through equal wires to equal gapped plugs, should be the same. If not, again, there could be a difference or a problem in the rotor or its tips or the terminals in the cap, or the spacing between cap terminals and the rotor tip terminal may be of different lengths????? ?

Let us know if you really mean one cylinder really fires stronger (which could be an engine or valve or cylinder, not an ignition problem) or that after swappign wires and plugs etc., one side really produces less of a SPARK????? ??

If you just mean one side fires stronger, post back and we will try and guide you through engine versus a spark difference problem.

HOWEVER, if the spark out one terminal (top or bottom) is always stronger, rergardless of what plugs or wires you use, Then I still suspect:

a) A cap problem like carbon or cracks or the terminal or its location relative to the rotor tip terminal; or, b) A rotor tip problem like cracks or carbon or distance to cap terminal; or, c) An uneven cam lobe problem (one wore more) or a bearign problem which may cause excess wobble which widening the gap, may help a bit for a while.

I sugegst you insepct also inspect the points for pitting or burning or oxidation and their gap at BOTH cam lobes and inspect the cap for cracks or carbon paths and the rotor to see if its tips are similar. Different distances between rotor tips and the cap terminals can alSo affect spark.

I hope this helps in the meantime, and Im sure clooney and all the other fine helpful people here can get you an answer. Let us all know what you find out.

Good Luck n God Bless you and the good ol USA

Ol John T Nordhoff in Indiana