Wico XB Distributor

NoDakInMN

Member
I recently acquired a late model "B". The tag has the serial number rusted out, so I cannot accurately state its year but it has the square axle housings, battery under the seat and a XB distributor, so I'm guessing it is around a 1950 or so. Anyway, my question concerns the XB distributor as I am new to these. The tractor has sat for some time and I'm in the process of trying to get it to run. Right now it is free, has compression and no spark. Carb will be addressed after I get spark, if necessary. I am used to mags and distributor systems, but this seems to be a bit of a hybrid of both. What I am looking for is a little help in troubleshooting this thing. Points look to be new and I dressed them up a little. I have 6 V at the connection on the side when I turn on the key. Rotor and cap look to be in good shape. So I'm guessing that I need a condenser at least. I know I could swap out the distributor for a mag, but I would like to get this running like Mother Deere originally intended.

Suggestions?
 
I'd rather have the distributor then the mag, myself. Like any battery ignition, it needs good points, capacitor, and coil. I
have had two XBs with bad coils and I just mounted an outside coil instead. Original internal coils run kind of hot and I
prefer them outside anyway. If you need it to look original, repro coils are still available.
 
open it up & check if that resistor is good. Have the coil and condenser tested. Make sure the points are contacting. I have a spare if you need it.
 
I have seen the small resistor located inside behind where the input terminal is located go open (based on olddddddddd memory no warranty that's how they are), you therefore have to insure there's voltage getting to the coil and points NOT just to that external terminal. You need to insure the coils LV Primary has continuity and isn't open. Sure condensors go bad but Ive seen those coils fail either due to an open in the LV Primary or HV Secondary, but often its HV breakdown in the Secondary thats the problem. In many years as a used tractor dealer I saw many of those go bad and the Delco battery powered coil distributor ignition or the Wico or other brand Magnetos were more reliable and easier to market in my experience, sure others may have different experience.

John T
 
Old time JD mech. told me those XB were problematic way back when new. Hard to get a proper fitting condenser. Sometimes they made too much spark and it would arc thru to the spark plug wire conduits. I'd upgrade to a Delco dist. or an XH series mag. instead of putting any money into an XB.
 
Mike, that's the very same thing I typically heard from farmers and dealers all over the Midwest and my experience when I dealt in used tractors. FWIW

John T
 
I had problems with an XB on my Model H. I initially tried to do some work on the XB to get it working better, but in the end I replaced it with a
Delco distributor and it made all the difference in the world. The Delco was a tight fit on an H compared to the XB, but I think a Delco
distributor may have been a late option on a B? Someone will correct me if I'm wrong.

Kent Petersen posts to ytmag and sells Delco distributors; that's who I got mine from. Might want to search for old posts to get his number.
 
You can still get about any part you need for an XB including a coil. I screwed around with one last winter in a nearly futile effort to get a hot spark. I finally got good spark out of it but it took a new coil to get the job done. Biggest problem I had was fixing the very worn fly weights. I suggested to the owner we could put a more reliable Delco on it but he wanted to retain the XB to keep it original.
 
First off, thanks for all the replies. I couldn't get back to respond sooner because of that four letter word called work.

Ok, a little more background on this tractor. It was a restoration project that got started on and got set aside for several years and that is how I came by it. It was a running tractor at the time it was idled and a fair amount of work had already been done on it. Points and rotor appear to be new and the cap may be as well as the contacts show no signs of wear. That is why my thoughts went to the condenser being bad as I have had that happen a lot on mags that have sat for some time.

But as I said, this is my first go round with this type of distributor and part of the fun for me is to learn how the different components work. So while this tractor may eventually wind up with a mag or a Delco distributor, right now my goal is to see if I can make this thing work.

So, with that said, I have some questions.

1. How do you access the resistor between the power terminal and the coil?

2. What ohm reading should it have?

3. What ohm reading should the coil have?

4. What is the purpose of the fly weights and how do you determine if they are worn?

5. Is there an internal wiring diagram for the XB? I have done a little looking online but with no luck so far.

I realize that some of these may have obvious answers but I have not yet had the opportunity to take the XB off of the tractor and my inspection so far has been limited to what can be seen after removing the cap.

For those who are curious, as I usually am, I gave $650 for this tractor. It was close, about 20 miles away. It has new rubber on the rears but needs new rubber on the front. It has a Rollomatic front end, a rockshaft, no plugs for hydraulics but it does have the carrier for a hydraulic cylinder. Tin is pretty good but I will need to replace the nose cone as it looks like something fell on it while in drydock. Battery box is shot but it came with another one in real good shape. Seat frame is kind of beat up but could be fixed, however I think I might replace it. I'd post some pictures but it seems that I forgot how to work Photo Bucket.
 
IIRC those are covered in a separate service manual for electrical equipment.
The flyweights are for the centrifugal advance.

Easiest way to work on one is to remove it from the tractor and take it to your work bench. The side resister just had 2 screws to hold the cover on. It comes out with the cover. You can also easily test them at the bench. Hook a battery to them and spin them or use a battery charger. I use a small trickle charger set on 6 volts.
 
I think there are some minor variations between the Wico XB4001B. and the XB4023. All get points set at .015" All use a
condensor with a capacity of .3 to .34 microfarads. Coil resistance is likely around 5000 - 8000 ohms from a plug wire
secondary to a primary. The coil is supposed to be tested under load by amp draw. It should draw 1.5 amps when making a
spark jump a .20" gap and be able to make 15,000 volts at any RPM. Flyweights take the place of the impulse on a mag and
retard the timing for better starting. Once running, it advances. Resistor is behind the rectangle with studs on it. As I
recall, it is wire-wound and variable resistance and acts like a voltage regulator. As it heats up, resistance increases. If
it IS open wire - just make sure it has some continuity and no coils have breaks.

I did have the problems with WICOs like some other's have. Lack of good parts support and not great tech support was our main
complaint when these things were current and not collector's items.
 
One more thing. Timing retard specs.
All XBs
#4000 -CW - 30 degrees
#4001 - CCW - 25 degrees
#4001L - CCW - 30 degrees
#4010 - CW -30 degrees
#4011 - CW - 18 degrees
#4013 - CW - 30 degrees
#4015 - CW - 35 degrees
#4016 - CCW 25 degrees
#4018 - CCW -18 degrees
#4023 - CC - 25 degrees
#4100 - CW -18 degree
 
Great questions, sorry I cant find my XB literature but will try to answer based on memory alone so no warranty. It's been a longgggggggggg time since I was a used tractor and dealer and slept since I worked on them lol so don't anyone have a calf now if this isn't 100% perfect .............


1. How do you access the resistor between the power terminal and the coil?

Its on the back side of that rectangular phenolic brown looking block where the input terminal is located HOWEVER you can test its continuity WITHOUT having to physically get right to it (see below)


2. What ohm reading should it have?

No specs here but a pure GUESS its low ohms, maybe 0.5 to 1+ ohm or so subject to temperature THE MAIN THING IS IT CANT
BE AN OPEN CIRCUIT (see below)


3. What ohm reading should the coil have?

Again no specs, but a pure GUESS is the LV Primary is very low ohms, maybe 0.5 or so to a few ohms while the HV Secondary is several thousand ohms. Again cant be open !!!


4. What is the purpose of the fly weights and how do you determine if they are worn?

It for centrifugal spark timing advance, I cant describe how worn or not.


5. Is there an internal wiring diagram for the XB? I have done a little looking online but with no luck so far.

a) Here's the wiring. Its NOT rocket science. External power stud gets voltage from ign when ON,,,,,,,,,,current then passes through the internal ballast resistor,,,,,,,,,,,,then through coils LV Primary,,,,,,,,,,then through points when closed,,,,,,,,,,to ground.

b) You can easily test to insure theres continuity from input terminal to coil (via ballast which is maybe 0.5 to an ohm or so) UNLESS THE BALLAST IS BAD OPEN !!!!!!!!!!! Then theres maybe another 0.5 to a few ohms to and through the coils LV Primary,,,,,,,,,,,,,then its to the points terminal,,,,,,,,,,,then to ground when closed. BASICALLY unhook the wire to the stud and put an ohm meter there and the other meter lead to the points terminal and with points OPEN you should read the total of ballast resistor plus the coil, maybe a few ohms total BUT IF ITS AN OPEN CIRCUIT EITHER THE COIL OR BALLAST IS BAD/OPEN. Id try it with condenser removed just in case the condenser was bad/shorted. WIRING NOTE Condensor is in parallel with the points !!!!!!!!!!!!

NOTE 1) Even if a coils HV primary has continuity under a low voltage check and isn't open it can still be bad and HV breakdown can occur. You need a real HV coil tester to really test it even though an ohm meter can show its bad if its total open. A low energy low voltage ohm meter can show if its BAD/OPEN but cant really prove its good and wont still break down under temperature and high voltage

NOTE 2) You need a real capacitor tester to check a condenser, but still an ohm meter can show if its definitely BAD. To DC once its charged up it should basically read an OPEN circuit, if it shows continuity to DC (once charged) its shorted and BAD. Its in parallel with points

NOTE 3) As far as above, when doing the ohm meter checks I described UNHOOK THE CONDENSOR in case its bad and a short circuit. A coil can still fire with no condenser at all IE removed but a weaker spark and points will burn prematurely.

This isn't the exact detail and numbers you were lookin for but knowing how its wired (terminal to resistor to coil to points to ground and what and where condenser is ) might get you by. Post back questions, but I'm more into electrical then the mechanical works of that XB.

John T LOngggggggggggg retired Electrical Engineer and rusty so no warranty but I try me best to help
 
Thanks Mike M, JDEM and John T, great answers.

I work in the HVAC field as a commercial/industrial tech and I have a capacitor tester along with multimeters, ect, ect, ect.. However my work is all with A/C except for some control signals in 0-10 Volt D/C. So when I dig into D/C I have to go back about 30 some years to my training. So if this sounds stupid, humor me as I forgot a lot of that over the years.

If I normally test a capacitor on a A/C system I do so across the two terminals. but as the condenser only has 1 terminal, my guess is that I check across the one terminal to the shell of the condenser, right?
 
I checked a Fairbanks Morse 6 volt disributor I have on the shelf made to interchange with the WICO XB. I measured aroun 1.2
ohms on coil primary circuit and 7800 ohms on the coil secondary. I am sure the WICO coil is similar.

Keep in mind the resistor is heat-reactive and not a fixed resistance. It is supposed to keep voltage to the coil down around
4-5 volts when the engine is running. It is supposed to allow full battery voltage when starting (approx 4.5 volts with a 6
volt system).

Look at the can-type coil image I posted with the built-in wire-resistor built in to the bottom. It is for a 40s 6 vot car but
the WICO XB is pretty much wired up the same.
a163639.jpg

a163640.jpg

a163641.jpg

a163643.jpg

a163644.jpg

a163645.jpg
 
Wow! Thanks for all the information!!! I am copying this stuff and pasting into a word doc and adding it to my file on JD information.

OK, I got a chance to take the distributor off tonight and found that there was a hole in the plate the resister was mounted to and it appears some form of wasp got inside and deposited all sorts of bad stuff in there. But I went forward and checked out what I could anyway. Despite the hole, the resister checked out but the insulation is frayed by the end that lands under the cap. The coil had .6 ohms on the primary and 6K and change on the secondary. Condenser is toast.

Now for the bad news, the wasp paper that was everywhere behind points plate pretty much made for a Wonderful World of Corrosion due to a combination of the paper and humidity. So the fly weights move but not at all freely and they stick. Everything looks salvageable but it is going to take some time to take it all apart and get it all cleaned up. Thus it comes down to the number of projects that I need to complete by Rollag and the amount I time have to do it in. So I think I am going to have to back burner this in order to get the "B" running and any bugs worked out by Labor Day weekend.

Here is my plan B for the "B"; I have a Wico X mag that only needs points and condenser to get it working. Since it looks like the XB it should keep the same look. That will allow me to get cracking on any carb issues I may have. The sediment bowl has a fuel shutoff on it that I can use for shutting the tractor down. Then later, I can take my time and go through this distributor in the way it needs. Thanks for all your help and because of that I now have a much greater understanding of this distributor than I did just a a couple of days ago.
 
The flyweights on the XB I worked on had come apart. A couple of slotted links link them together so they work as a unit. One of the little nubs on a flyweight had worn so a link fell off, got caught up in the works and was mangled up. I had to make a new link. I'd say if they are still as a unit leave them alone.
 

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