[AT] question on use of resistor on coil

[Cecil E Monson]

>   For a fact, the 420 ignition system is the same as the 40 ignition system as 

stated in the 420 service manual.  6 volt and uses the Delco Remy No. 1115379 coil.

  No resistors in the ignition system.  Only in the lighting system for "dim 
lights".
>     My engines that sit, be them John Deere, Willys, Wisconsin, etc. almost always 

give me starting troubles until I clean the points.  Often I clean them by 
installing

new.  Sometimes touching up with a file will work.  I have had corrosion in the

primary wire and also at the switch contacts which set up a resistance that ruined

or completely eliminated a spark.  Making more cleaning and replacing necessary.

Moisture induced problems, I think.  On engines that are used constantly, this 
never

seems to be a problem.  You could give me the 420C and I would see that it runs 
more

often.<g>
> 
> Ron Cook
> Salix, IA

> In 6 volt systems the external ballast resistor is normally not used.  The
> current though the coil, which is approximately 6 amps, is the same both
> when starting the engine as well as when running the engine.  A current of 6
> amps through a one ohm coil results in approximately 36 watts of generated
> heat which the coil should be able to dissipate.
> 
> Hope this doesn't cause any confusion -
> Dudley
> Snohomish, Washington



	Ron and Dudley, thanks to you both. This was what I suspected and being
as I respect the opinions of both of you, I am now sure that these coils are all
6 volt coils. If they have an internal resistor, they will be marked 12 volts, I
am sure.

	FWIW, Ron, this coil has "12 volts" painted on the side of it in white
paint even though the box says "resistor must be used" so it could be a 12 volt
coil and would account for the yellow spark if the points are OK. I have several
other good coils that I know are 6 volts and if I get a chance, I'll substitute
one of them and see.

	Being as I could feel a gritty side to the points with the little "point
file" I got from Sears, I am pretty sure there is heavy pitting on the one side
and will just put in a new set of points.

	I have suspected corrosion in the ignition switch and erratic operation
in the past but have not been able to prove it. On the crawler, it is almost
impossible to get to the switch without removing the entire loader frame which
weighs just about a ton by itself. It's one of the pleasures of owning a loader/
crawler. :-(  The dash has screws that hold it in place but with the loader
frame in the way, you need 4 foot long arms with extra joints to work on it
once it is loose.

	Dudley, It seems to me the voltage at the coil dropped to under 5 volts
when I checked it with the ohmeter. It could indicate an internal resistor when
going by your comments.

	Thanks again to you both and Ron, if I decide to junk the 420, I'll
bring it out to you. ha ha ha ha

Cecil

	

-- 
The nicest thing about telling the truth is you never have to wonder
what you said.

Cecil E Monson
Lucille Hand-Monson
Mountainville, New York   Just a little east of the North Pole

Allis Chalmers tractors and equipment

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