1952 B distributer CLOONEY

~On the Wico 6 volt XH distributor the best place to check for power is to remove the distributor cap, then you should find a wire junction screw near the right lower corner of the points breaker plate [you should see the resistor wire coming from a hole in the housing & the coil's primary wire coming from the coil attached there]. With the ignition switch [turned on] & the points OPEN you should have close to battery voltage at that terminal screw. With the points CLOSED the voltage should drop to 4-5 volts. If you don’t have any voltage period, you have either a burnt up [open] resistor, or the terminal stud sticking out the front of the distributor is rusted & corroded & not passing current [common on the XD]. If the terminal post sticking out the front is corroded you have a couple of choices,,, first, you can try to remove the nuts & clean the post & nuts [that’s risky as the stud usually breaks off], or second, wire brush the post & stud & use a little file on the exposed nuts to clean them, then cut the attached wire & add a new crimp on terminal end, then install it on the remainder of the stud with a new nut & washer. [that usually works good]

~If you have power at that internal terminal screw with the points both open & closed, your resistor & power stud are both good & are passing current. If opening & closing the points doesn’t change the voltage on that junction screw from battery voltage to down around 4-5 volts you have a bad coil, defective points, open or short in an internal wire, or poorly grounded distributor or breaker plate.

~If the voltage at that terminal screw is always at battery voltage [even with the points closed] try using a jumper wire from the tractor frame or other CLEAN ground & touching the points wire connection screw on the side of the points, if the voltage at that resistor junction screw then drops to around 4-5 volts you have a points problems [probably oxidized points], or poor breaker plate ground. If the voltage at that junction screw is always 4-5 volts or under you have a short to ground in the points, or short to ground in the condenser, or shorted coil. If there is/was a short to ground in the coil or the wire running from that junction screw to the coil you probably would have a burnt up resistor [that resistor is very fragile]. Be very careful when using a jumper wire inside that distributor as you NEVER want to ground the resistor junction screw or the wire between the resistor junction screw & the coil, or there is a good chance the resistor will burn up very quickly. Grounding anything on the points side of the coil won’t hurt the resistor so keep that in mind when working on that XH/XD.

~If you do in fact have a 6 volt Wico XD [the “B” should] you can use an ohmmeter & measure the resistance of the dropping resistor [it should be somewhere between .8 & 1.2 ohms. You can also measure the coil’s resistance,,, the coil’s primary resistance [between power wire that hooks to that resistor junction terminal & the coil wire hooked to the points] should probably be somewhere around .5 to 1 ohms & the coil’s secondary resistance [measured between the coil center contact button & coil's ground wire] should probably be somewhere between 5.5 & 8 K ohms

~Now that I have probably really confused you with the above I will give you a quick & dirty way to test the coil & it’s output… First, remove the distributor cap, then fasten a wire [a paper clip works good] to one of the cap attaching screw holes & bend to within 1/8” of the coil’s center contact button, now turn the ignition switch on & crank the engine & look for a blue spark to arc between the wire & coil button [if you have a nice blue spark, the coil, points & condenser are good. If you don’t get a spark while cranking, turn the engine so the points are open & with the ignition turned on use a screwdriver & wiggle it between the open points [if you get a blue spark now you have dirty or malfunctioning points. If you still don’t get a spark check for power at the resistor junction terminal inside the distributor, then check for power at the points terminal on the points [points must be open] if you have power at the points, try disconnecting the condenser & then wiggling the screwdriver between the open points again [if you get a spark now you have a shorted condenser [you will have to pull the breaker plate out to access the condenser [it's burried in a pocket in the lower L/H corner of the distributor housing] . If you still don’t see a blue spark suspect the coil is bad…..

Anyway, if you set the DVOM to measure resistance - click to the OHM scale that says this Omega, or this symbol:

W

Steve