(800) 853-2651
SHOP NOW

E4A Magneto

E

EM Iowa

Member
I just installed a E4A magneto on the F-20 and I was wondering if there is anything I need to do to it mechanically before I bolt it down and attempt to start the tractor. I purchased the Magneto at a farm sale, never touched it, put it on the bracket and it produced a spark. So should I just time it and oil the bearings and call it good? Any tips on timing the mag?
And how does the retarder work? I should start the engine with it half-way on and then advance it, correct?

?
 
Did you note where the rotor was pointing when you removed the mag? If you didn't you need to bring No1 piston near the radiator to tdc on the compression stroke. Then rotate the rotor so its aligned with the No1 plug tower and install it. Hal
 
I would never put an unknown magneto in service without taking it apart and greasing the bearings. If I were you I'd send it to Kirk and have him go through it. Magnetos with dry bearings will self destruct.
 
What about if I oil the bearings and turn it over slowly, that should lubricate the bearings. And then try to start the motor. How much does Kirk charge? I've seen the mags he has rebuilt, they're beautiful!
 
oil it sparingly. You don't want a bunch of oil slinging around in there. That's why the bearings are packed with light grease. You will probably be fine for this show but don't plan on leaving it that way. I'm sure Kirk will be fair with you.
 
On the last F-20 I restored, I put a mag right off the parts tractor that had ran for years, and that mag is still doing fine to this day. I oil it before I start it. That's why I though I could do it this time.
 
Even if the already produces a good spark, I would still take it apart and clean and relube the bearings. Out of all the mags I have taken apart and rebuilt, almost all the bearings were caked with old dry grease. Clean it up good and pack the bearings with wheel bearing grease, then you will never have to oil it again.
 
If I disassemble it (which I'll have to figure out) is there anything I can screw up? A manual and pictures would be nice. If I send it to you Kirk, can you recharge magnets?
 
(quoted from post at 09:00:38 07/13/13) If I disassemble it (which I'll have to figure out) is there anything I can screw up? A manual and pictures would be nice. If I send it to you Kirk, can you recharge magnets?
Click to expand...

There are some things you have to watch out for when taking it apart, but take it slow and you can figure it out. I do have a charger to recharge magnets and I do that when I rebuild magnetos, but I am not convinced that it is a requirement. I can not detect an increase in spark intensity after recharging the magnet.
 
I'll chime in a tad on the "charge the magnet" subject. At operating speed, it doesn't have a huge impact, however, at slow, starting speed, a "stronger" charged magnet will produce a better spark at lower RPM's.

The E4A and the F4 are designed and known to produce some of the "hottest" spark a low rpm's as compared to other mag's of the same era. This becomes a case of "optimal" vs "works".

There is an excellent book that covers a lot of this by now deceased Neil Yerigan, "How to Restore Tractor Magnetos".

Here is a link to the book:

http://www.amazon.com/How-To-Restor...&keywords=how+to+restore+tractor+magnetos
 
Common sense says that a stronger magnet makes a hotter spark. Take the magnet off & it won't produce a spark no matter how fast you spin it.
 
well, Teddy, you are correct. If you want to get down into the physics behind all this, it has to do with the conservation of mass and energy. Each electron has mass, and thus requires KE (energy) to move it. A weak magnetic field, but fast RPM's will produce a reasonable spark. A strong magnetic field, and low RPMs will produce an equivalent spark. MASS x Velocity = KE.

KE is requires to increase the PD (potential difference) between the 2 poles in a magneto. By passing the copper windings in a magneto through a magnetic field, a PD is represented by induced voltage. Now, this is where the coil comes in. This low voltage (PD) is introduced into the primary windings of the coil. When the rotor turns (and the points open) the field collapses. The result is a step up, or induced voltage on the secondary windings (Which, will be MUCH higher in voltage). Thus, you get your spark. reduce the voltage to the primary (weak magnet, low rpms), and the resultant spark is "weaker". Increase the RPM's, and the KE increases, and the spark is sufficient to run the tractor. Hard as the hubs of heck to start though.
 
(quoted from post at 13:25:41 07/13/13) Even if the already produces a good spark, I would still take it apart and clean and relube the bearings. Out of all the mags I have taken apart and rebuilt, almost all the bearings were caked with old dry grease. Clean it up good and pack the bearings with wheel bearing grease, then you will never have to oil it again.
Click to expand...

Kirk,
What does a rebuilt E-4A consist of?
 
Here is my process,

First I take the magneto completely apart and examine everything for broken, missing or worn out parts and replace with good used parts from my stock. Then I clean off all the old dirt and grease in solvent. Next I bead blast the parts inside and out to clean them to bare metal. Then I assemble all the now clean parts, and pack the bearings with wheel bearing grease so they do not need to be lubed again. Once it is assembled I adjust the points and give it a test run. Note: I do not install a new coil or condenser as part of a standard rebuild, just good used ones. New coils are very expensive and most people don't want to spend the extra $$. Since both the coil and condenser are integral with the rotor, if I find a bad coil, I just replace the entire rotor with a good used one from my stock of parts.

Once I am satisfied the magneto is working like it should, I spray paint the cap, magnet and manual impulse coupler a gloss black and the rest gets a gloss clearcoat. After final assembly I zap the magnet on my magnet charger and check to make sure it is still putting out a good spark. Finally it gets a new brass name band over the magnet.
 
(quoted from post at 01:20:19 06/13/14) Here is my process,

First I take the magneto completely apart and examine everything for broken, missing or worn out parts and replace with good used parts from my stock. Then I clean off all the old dirt and grease in solvent. Next I bead blast the parts inside and out to clean them to bare metal. Then I assemble all the now clean parts, and pack the bearings with wheel bearing grease so they do not need to be lubed again. Once it is assembled I adjust the points and give it a test run. Note: I do not install a new coil or condenser as part of a standard rebuild, just good used ones. New coils are very expensive and most people don't want to spend the extra $$. Since both the coil and condenser are integral with the rotor, if I find a bad coil, I just replace the entire rotor with a good used one from my stock of parts.

Once I am satisfied the magneto is working like it should, I spray paint the cap, magnet and manual impulse coupler a gloss black and the rest gets a gloss clearcoat. After final assembly I zap the magnet on my magnet charger and check to make sure it is still putting out a good spark. Finally it gets a new brass name band over the magnet.
Click to expand...


Thanks Kirk, That sounds like a pretty thorough process.
Do you have a website, e-mail address or contact info?
 
You must log in or register to reply here.

Similar threads

1
Intermittent spark from magneto
2
Replies
28
Views
918
ASE guy
A
R
H magneto no spark after tune
Replies
12
Views
368
560Dennis
560Dennis
R
Magneto question
2
Replies
22
Views
1K
WeirdDeere
W
M
1948 case la magneto
Replies
11
Views
459
J Hamilton
J Hamilton
N
1939 Case RC magneto
Replies
5
Views
277
J Hamilton
J Hamilton
Tractor Parts Tractor Manuals

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.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top