[Farmall] Ignition Systems 101 was: Farmall C question

Thu Sep 2 05:54:19 PDT 2004

When you convert to 12 volts, you put a ballast resister in the line to 
keep the voltage to the coil (more or less) at 6 volts.

Mike

Stan Bass wrote:

> Cliff, Do you mean literally to go off the resistance on the primary
> to select the condenser, or the current drawn? ie: If we covert to a
> 12V system do we need to spec a new condenser? The primary resistance
> goes from 1.5 to 3 ohms, but that is to keep the current the same at
> about 4 Amps. Stan(VA).
> 
> cliff king wrote:
> 
>> Not a problem guys..I am always willing to give assistance or
>> thoughts, however, I tend to take the technical route because that
>> is the way I was taught. I can't recollect the correct ratio of
>> condenser to coil capacity..but I would sure research it if needed.
>> I have it in my collection of tech manuals somewhere around here.
>> You have to go off the primary winding of the coil due to the
>> magnification in voltage developed in the secondary winding needed
>> to fire the fuel ignition device( spark plug). 90% of the time I
>> work on/tear up/repair diesel engines so I tend to forget some of
>> the basic ignition stuff required to ignite gasoline. I didn't
>> intend for the message to be sarcastic..but I deal with wanna-be
>> parts changers on a daily basis (most of whom have no earthly idea
>> what the hell they're doing, let alone knowledge of how it's
>> supposed to work in the first place).
>> 
>> Cliff
>> 
>> Stan Bass <headlight at erols.com> wrote: I would vote to see your
>> thoughts on this, Cliff. Now this is from memory... but I recall
>> the last condensers I checked were about 1.2 uF for the Farmalls
>> and about 0.2 uF for the Cub Cadets? And coil selection (1-1/2, 3,
>> or 4-1/2 ohm coils). Our old tractors seem to draw about 4 Amps, so
>> I know our old 6V coils are about 1-1/2 ohm and the 12V ones are
>> about 3 ohms; but I read somewhere (wish I had saved it off) that
>> single cylinder motors like the Kohlers in IH Cub Cadets use a 
>> 4-1/2 ohm coil (but I've checked several and all so far have 3 ohm 
>> coils?). Trying to remember what it was based on, voltage, current,
>>  cylinders and RPM range? Don't worry about going over anybody's
>> head, that's how we learn. My only comment from doing this in the
>> past, is please state when things in an explanation are
>> over-simplified in the interest of brevity. That way if someone is
>> researching it further on their own, they know where the back holes
>> are ;) Thanks, Stan(VA).
>> 
>> cliff king wrote:
>> 
>>> In my garage, which I operate as a business, we don't guess. Put
>>> yourself in the customer's shoes standing there listening to
>>> someone tell you why the bill is outrageously high for a bunch of
>>> parts installed that didn't fix the problem. Use a test light and
>>> do some diagnostics instead of being a "parts changer at someone
>>> else's expense". I would lay odds on the condenser being bad.
>>> Practically every mag I overhaul has to have the coil and
>>> condenser replaced. The condenser is a miniature storage
>>> capacitor for the coil. The point set is simply a mechanically
>>> operated switch that turns the voltage stored on and off. I would
>>> say that 9 out of 10 mags have points that are ok, just need the
>>> mountains filed off to operate at the proper clearance. I could
>>> go into more detail as to the proper microfared capacity matching
>>> of the condenser to the number of windings that are in an
>>> ignition coil...but I'm afraid I would lose some of the more
>>> simple minded folk on the list. Cliff
>>> 
>>> "soffiler at myeastern.com" wrote: In the trade, that's called "plug
>>> and chug". Take an educated guess, replace parts, repeat as
>>> necessary until problem is solved. It is generally considered a
>>> less desirable problem-solving technique versus doing some basic 
>>> diagnostic work. I realize that sometimes it's just more 
>>> convenient, or less intellectually taxing, to use the plug and
>>> chug approach.
>>> 
>>> Steve O.
>>> 
>>> From: "Jeff & Ginny Pomije"
>>> 
>>> 
>>>> I had this happen with my Super C. The points and condenser
>>>> were replaced and it ran fine.
>>>> 
>>>> Jeff
>>>> 
>>>> 
>>>> 
>>>> -------- Original Message --------
>>>> 
>>>> ==> From: "Kevin Bish" ==> Date: Tue, 31 Aug 2004 08:21:19
>>>> -0400
>>>> 
>>>> I was using my C the other day when it just died. I checked for
>>>> spark at the plugs and didn't have any, no spark from the coil
>>>> either. Tried 2 more coils with no luck, the last coil I tried
>>>> was off of my Super M which I know it works fine. Could it be
>>>> the condenser maybe? The points look to be fine also. Doesn't
>>>> appear to have any wires loose or grounding out. It has a 12
>>>> volt generator charging system. Any suggestions? Thanks Kevin.
>>> 
>>> _______________________________________________
>> 
>> _______________________________________________ Farmall mailing
>> list http://www.antique-tractor.com/mailman/listinfo/farmall
>> 
>> 
>> --------------------------------- Do you Yahoo!? Win 1 of 4,000
>> free domain names from Yahoo! Enter now. 
>> _______________________________________________ Farmall mailing
>> list http://www.antique-tractor.com/mailman/listinfo/farmall
> 
> _______________________________________________ Farmall mailing list 
> http://www.antique-tractor.com/mailman/listinfo/farmall
> 

-- 
Mike Sloane
Allamuchy NJ
Email: (msloane at att.net)
Website: <http://www.geocities.com/mikesloane>
Blog: <www.mikesloane.blogspot.com
Tractor images: <www.fotki.com/mikesloane>
Work: none - retired

Our elections are free, it's in the results where eventually we pay.
-Bill Stern, sports announcer (1907-1971)