[Farmall] Ignition Systems 101 was: Farmall C question

[Stan Bass]

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.
> > _______________________________________________
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