Magneto with external coil

[Clubless]

Here is wiring diagram I used to wire up the alternator, ammeter and switch (to excite the alternator).

One difference that I have is the ballast resistor is between coil and distributor instead of between switch and coil. That’s where the PO had it. I assuming it’s a 12v coil.

Also have a question about how I have the coil mounted. I have it pointed straight down just above the distributor cap. Does a coil care which way it points?


Gary

[Glen]

Hi,
good that you got the Cub to run and alternator to charge.

You should check the clutch pedal free play. It should be 1", for Cubs serial number 32229 and above, with the external adjustment. It is measured at the surface where you put your foot.
If the pedal works hard, it might need lubing at the base, where it goes into the clutch housing. They can get tight from sitting. Keep working penetrating oil into the pedal base. Usually the pedal base will pull out of the housing about 1/4", this helps to work lube into it. Push it back in when done.
If it loosens, oil it with motor oil.

The clutch pressure plate fingers may be too low, a sort of common problem on Cubs. If they are too low, the clutch may not release all the way, then it won't shift without grinding.
Also if the fingers are too low, the metal part of the bearing and the bearing holder can hit on the pressure plate parts, making a grinding noise. Do not push the pedal far enough for the noise to happen, it can damage the parts.

The graphite sticks out of the metal part of a new throwout bearing 5/16", they can wear down from use. If it is worn too low, that can cause problems with it releasing correctly.
They have said on here to lube the throwout bearing grease fitting with cheap grease, so the oil in the grease will absorb into the graphite. The original bearings have a small hole on top, for excess grease to come out.
I put a thin layer of grease on the front of the bearing also, that contacts the fingers.

You could use the spray lube on the finger pivot pins.

Below is a page from the 1950 Cub owner's manual showing adjusting the clutch pedal free play, and a pic of the clutch.

http://farmallcub.com/rudi_cub/www.clea ... e%2040.jpg

Below is a post about setting the height of the pressure plate fingers.

viewtopic.php?f=141&t=66543

Below is a pic from TM Tractor of the pedal base. About 2/3 of the length of the shiny part makes contact in the hole made in the clutch housing. So it needs some oil to get in that far.

[Clubless]

Glen

Also have a question about how I have the coil mounted. I have it pointed straight down just above the distributor cap. Does a coil care which way it points?


Gary

[Eugene]

Also have a question about how I have the coil mounted. I have it pointed straight down just above the distributor cap. Does a coil care which way it points?

No

[Glen]

Hi,
It doesn't matter which direction a coil is facing, like Eugene said above.

Below is a pic of a new throwout bearing, the material sticks out of it 5/16", when they get worn down to near the metal, they need replacing.

The 2nd pic shows where to measure when setting the pressure plate finger height. It is measured with the plate assembled on the flywheel.

[Clubless]

Eugene and Glen...thanks for your response to my questions. You guys are such a big help!

Thought I would post a couple of pictures, one of the TOB and one of the alternator setup.

Gary

[Glen]

Hi,
It looks like the throwout bearing is good in your pic.
It looks like one finger is lower than the other in the pic, but hard to tell, sometimes pics don't show exactly.
I would check the finger height.
The fingers should be the same height, so the throwout bearing has a flat surface to push on.
Be sure to lube the bearing, they should not be dry of lube.

When you adjust the fingers, you can loosen the bolt on the clutch pedal adjustment, turn the adjustment, and move the throwout bearing back, so there is more room between the bearing and pressure plate for working.
Measure the pedal free play first, so you know if it was right.
You have to set the free play after done working, if you moved the bearing back.

[RonT]

"One difference that I have is the ballast resistor is between coil and distributor instead of between switch and coil. That’s where the PO had it. I assuming it’s a 12v coil"
The ballast resister should be on the wire supplying current to the coil. Although it is running, the resister is having the same effect as points with a little bit of resistance.

My 2 cents
Ron

[Eugene]

The ballast resister should be on the wire supplying current to the coil. Although it is running, the resister is having the same effect as points with a little bit of resistance.

It doesn't make any difference which resistor comes first in a simple series circuit. The ignition coil primary winding and the ballast resistor are wired in series. The voltage drop is cumulative meaning that the voltage drop across the resistors are added together to obtain the total voltage drop.

[RonT]

With regard to ballast resister placement:
Actually, it does make a difference. The ignition coil relies on a oscillating voltage between the coil and condenser after the primary current is interrupted by the points opening. When working properly, the voltage builds up to the point where it will arc across the plug gap. Placing the resister in this portion of the circuit could cause the spark voltage potential to be limited.

[Clubless]

So Ron, should I have the ballast resistor before or after coil?

Thanks
Gary

[Eugene]

Place the ballast resistor in front of the coil if it makes you feel better.

https://www.bing.com/images/search?q=Se ... ORM=IDINTS

Check out the above link. Notice that voltage oscillations between the coil and condenser occur after the spark plug has fired. Also note that there is some minor ripples in the coil's circuits as the coil saturates after the points close. Once the coil is saturated, the circuits flat line until the point open and the plug fires.

[Clubless]

Eugene,

I’m going to leave ballast resistor between coil and points.

Thanks for the link, but that information is way over my head LOL

Gary

[Clubless]

Hi all,

Got a couple of updates on the Cub regarding coil and new compression readings.

First the coil, since I have it mounted pointing straight down I noticed some marking on the bottom of coil (had not looked there before). The marking is TE6B4. A quick Goggle search offered up information that the coil is 6v used in VW's & Porsche ignition systems. I never imagined the ole tractor had some Porsche in it . Does this new information impact where the ballast resister is located? The tractor is 12v with alternator.

When I first checked compression (before I had it running) the readings were 90,0,0,30 (dry) and 180,30,30,90 (wet). Since I have been running engine for 10-15 minute durations on a number of occasions, I wanted to see if compression had improved. Dry tested today with the following readings; 120,118,85,120. Put a squirt or two of oil in #3 and it came up to 90. I was really pleased with readings, although I would like #3 to be more in line with the other cylinders.


Gary

[Eugene]

Does this new information impact where the ballast resister is located?

No.

I would add SeaFoam to the oil and gasoline. Operate the engine/tractor for a considerable length of time, something like 30 or 40 hours, then again check the compression.