Ford 641 Workmaster electronic ignition

TDJD

Member
My Grandfathers 641 Ford has been having ignition problems for a year (or so). I?m 99% sure the problem is ignition. It will stop running, or not start. I?ve tried to fix it, but I gave up, and we let a friend (who is really good at working on Ford tractors) try to fix it. Even he couldn?t fix it. He said we should switch it to electronic ignition. So my question is does anyone here have an idea on what to do to fix it? Or if electronic ignition is the way to go, what are the good, and bad points of it? We have determined that the problem is at the coil, or after it. We?ve tried a new coil. New points, rotor, and condenser (6 times). And new plugs.
Thanks
 
Best advice is to get it working with the breaker points, and only THEN attempt to "upgrade", if you are convinced that's what you want to do.

If it is not in running order when you attempt to "upgrade", you only add more unknowns to the mix.

Based on what you have done, I would check that the "pass through" terminal stud in the distributor is not shorted to the distributor body, and that the little copper strip between that terminal and the breaker points is not cracked or broken, and is not shorted to the distributor case.

Check that out, then try again for spark.

If still no spark, connect an unpowered test lamp between chassis ground and the pass-through distributor terminal, turn on the ignition and report back as to what the light does during cranking.

You can copy the following link and past it into your browser to view a GOOD manual on how Kettering ignition systems work.

Even though it's a John Deere manual on a Farmall site, the information directly applies to your little Ford.

http://farmallcub.com/rudi_cub/www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/FOS-20%20Chapter%206-Ignition%20Circuits/index.html
 
I would say that to do an electronic ignition conversion is pointless. . .

If you've replaced your ignition components 6 times (correctly....) and replaced the coil with a known good one, then your "ignition" problem is probably in the carburettor and fuel delivery system. (Whats that old mechanic's dictum- 99% of ignition problems can be traced to the carburettor."?). I would also get a general idea of the well-being of your engine by doing a compression check before getting any further into the weeds and throwing even more money at the undefined problem(s) you may have.


As far as the effectiveness of the electronic conversion kits, I have a few Fords around here (N series, 100 and 01 tractors) and the electronic conversions on them have made them start and run better and perhaps made them a bit more reliable.
No complaints except the initial costs!
 
So instead of throwing $$$ at it learn to do some simple trouble shooting.
#1 check that you have a good blue/white spark at the center wire of the distributor cap and at all 4 plug wires that will jump a 1/4 inch gap or more.
#2 pull the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in less then 3 minutes.
#3 when was the last time. you serviced the air cleaner and dumped the mud and water and filled with fresh oil.
Post back what you find so we can help you more
 
Do some basic troubleshooting first.

A test light is easiest.

Ignition on, ground the clip of the test light, probe to the ignition switch side of the coil. Should have voltage there. Try wiggling the ignition switch and the associated wiring to be sure there is a solid connection. Be sure the voltage is there when cranking.

Move the probe to the distributor side of the coil. With the points closed, should have 0 volts, points open should have near battery volts.

With the test light still on the distributor side of the coil, crank the engine through. The light should flash, on when the points are open, off when closed.

If the light stays on, the points are not making connection, the wire from the coil to the distributor is broken, the distributor or breaker plate is not grounded, or the distributor is not turning.

If the light does not come on, the points are closed or grounded (improperly connected), shorted condenser, wire from the coil to the distributor is shorted to ground, the coil is open internally, or the distributor is not turning.

Each time the points open, the coil should deliver a spark. A good spark will jump 1/2" or more.

That gets a spark out of the coil. Next check that the spark is making it to each plug. At the plug end of each wire, it should deliver a 1/4" spark to ground.

If the problem is intermittent, carry the test light, be ready to check when it fails.

Is this still 6 volt? Or has it been converted to 12v?

It is essential that it has the right coil or coil/resistor combination. Coil selection can be confusing. A 6v coil will have about 1.5 ohms resistance across the primary terminals out of circuit. A 12v coil will have about 3 ohm resistance across the primary terminals out of circuit. Or you can use a 6v coil and a 1.5 ohm resistor for a 12v application.

Most coils are marked as to what their application is. Don't go by the box or what the counter person tells you, check it ohms. or go by the part number on the coil. The wrong coil will give a weak spark, heat up and break down, or rapidly burn the points.

Points and condenser... A touchy subject! Todays ignition parts are all aftermarket, not near the quality that they were back in the day. Common for them to be bad out of the box, or be very short lived. Everything must be right for them to last and work properly. As said, the coil must be right. And the distributor needs to be in good order. A worn shaft bushing will not keep the points set properly, they will arc and burn.

That is where electronic conversion comes in. It is forgiving of a worn distributor, and eliminates the poor quality points. But that's all... It won't solve existing no spark issues, and it must have the proper coil resistance. It is also voltage and polarity sensitive, so be sure to specify when ordering.

Let us know...
 
The engine was completely overhauled less than 400 hours ago. I put in a new gas tank, and rebuilt the carburetor. I know there's gas I the engine but it didn't even try to fire, and when it would stop it was like the key was turned off. That's why I'm sure it's not gas.
 
I forgot to say that each time I changed the points and condenser it would run for between a few months, or a few minutes. I took the air cleaner out and cleaned it last summer. The gas runs out of the carberator at a good stream. The ford mechanic checked, and when the tractor will run it has a good spark. But no spark when it won't run.
Thanks
 
STOP changing condenser good chance that is where your problem is. Put the old condenser back in if you still have it. Also double check where the wire goes into the side of the distributor and make sure it is not shorting out there because if it is it will not have spark. My Ford 841S had the insulator in the side of the distributor go bad years ago and it now has a wire in the hole with silicone holding it in place
 
Steve, thanks for the advice! I?ll check those ideas out. The tractor is 6 volt. And the coil is the original 6 volt coil. We switched the coil to a new one form tractor supply, but we determined that it was bad out of the box, so we switch back to the old one and it ran for a while but then it quit again. Switch the points and condenser, and keep going.
 
I have two Fords with the same 134 Red Tiger engines. A 641 and a Jubilee. I converted both to the standard Pertronix Ignitor I "pointless" conversion, as one person put it here. And yes, it IS literally a pointless conversion and that is all. There is no increase in potential max spark energy. Just an increase in reliability and timing stability. I do not know what your intermittent issue is and have no idea why a guy "good" on Fords failed to figure it out. That said, since I have no idea what your problem is - I have no idea if installing a breakerless kit will fix your problem. Generally speaking, it should make no difference if the OEM system with points is working properly. Some installs of the Pertronix kit allow you to eliminate the ballast resistor. So that is one part of the system, if you have it, that might be eliminated.
 
The condenser is the first thing we changed and that fixed it for a couple months, but then it quit. I do still have the old condenser. I?ll check where the wire goes into the distributor. Thanks
 
We tested the coil, and it appeared to be good. But we can try a new one if you think that might be it.
 
I have not changed a condenser in well over a decade due to so many being bad right out of the box. I even have a few that I did change out decades ago in one of my tool boxes that I would use if I need one
 
Coil can/will work for say 30 minutes then get hot and then stop working. There is no way to test the hot coil being bad things. Had the coil on my 841S go bad and it would run for 30 minutes or so and then died and not run till cold. Had an old Chevy pickup sitting around and took the coil off of it and it is still on the 841S
 
Though the diagnosis tips and direction is likely wise, I just converted a Ford 4000 (3cyl) to the PerTronics ignition. Works great. Fired off on first compression stroke. Also used their 40k volt coil. Make certain you either get the 3.0 ohm coil, or have an external resistor.

One quick thought... Is your 641 still 6 volt, or converted to 12 volt. Perhaps your issues might have something to do with that? I do think you'll need to be converted to 12 volt to use the PerTronics.
 
Right now it?s about 20 degrees outside. If I try the starter, or pull it with the truck, it won?t start. So I wouldn't think it?s because of heat, but I suppose it could be.
Thanks
 
Coils get hot no matter how cold it is out side just like a ballast resister will get hot no matter what. But when 20 out it could also be a fuel problem and or spark. When cold it take a richer fuel mixture to start one up due to the cold
 
It makes no difference if 6 volt or 12 volt. 6 volt does not use an ballast resistor and the 12 volt system does (with the same coil). No difference if you convert to a Pertronix electronic either. You can buy a 6 volt system kit or a 12 volt system kit.
 

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