[Farmall] Need Expert Opinion

[Charlie V]

Hi Carl,

The guys at NAPA have it correct.  When my IH 340 needed a new
resistor a couple of years ago, (about the third time in 12 years) I
found I could buy the No Resistor Required Coil for about $2.00 more
than a resistor.  Not a hard decision.  I installed it without a
resistor and have never looked back.  It starts much better and runs
fine.  I am pleased so far and the coil only cost $15.00.  That coil
will be pretty warm to the touch when the motor is running, probably
because it is being a resistor as well as a coil.  The current
delivered to the distributor from the coil is stepped down to around
4.5 Volts if I remember correctly, so no threat to the points as the
full 12V would be.

Charlie V..

On Thu, Oct 27, 2011 at 7:03 AM,  <szabelsk at gdls.com> wrote:
> The H died last weekend and I traced the problem to the coil apparently
> having an internal short. Had no spark at the plugs, and the coil was warm
> while the ignition switch was on, and something was draining the battery.
>
> The PO had converted the H over to a 12V system. Figured I go get a new 6V
> coil and change the condenser and points while I was at it. After removing
> the coil I noticed it was marked 12V, not 6V. Also, the resistor that
> should be in line with the coil was actually in parallel with it. Don't
> know what value it is supposed to be since it was broken and I believe the
> one end should have been grounded, but wasn't. This is probably what fried
> the coil since it should have seen twice the current.
>
> I believe the entire resistor is there, it's just broken near the one lead
> that was supposed to be connected to ground. Measured what was there and
> got about 1.2 ohms. I figure the PO was using this resistor to cut the
> current in half at the 12V coil (wired from ignition switch to one end of
> the resistor, same end of the resistor wired to "+" on the coil). Maybe
> the PO also swapped out the points and condenser with 12V pieces to make
> the whole thing a 12V system(???).
>
> Anyway, since I was going to replace the points and condenser with
> standard 6V parts, I figured I'd just use a 6V coil with the resistor in
> series to drop the voltage down. Went to NAPA and picked up a 1.20 ohm
> resistor (ICR13), a 6V coil (IC7) and a tune up kit for the ignition
> system. When I got home I noticed that the coil is marked "NO EXTERNAL
> RESISTOR REQUIRED". I measured the coil resistance and read about 1.3
> ohms.
>
> Now I know that the resistor is needed to drop the 12V down to 6V, by in
> essence making the total circuit resistance twice what the coil resistance
> is (somewhere between 2.4 to 3. 5 ohms total) and dropping 6V across the
> resistor.
>
> My question is, with the  "NO EXTERNAL RESISTOR REQUIRED" marking on the
> coil, should I still use the resistor? If I don't, then I'll be putting
> 12V to the coil, and the total resistance will only be somewhere in the
> area of 1.3 ohms. Probably burn the coil out real fast.
>
> If I put the resistor in, I'll drop the voltage to 6V and have the
> required 2.4 to 3.5 ohms total. But what does the  "NO EXTERNAL RESISTOR
> REQUIRED" now mean?
>
> Is this marking there because this coil has other applications that would
> allow eliminating the in line resistor, and should I just ignore it?
>
> I did ask the guys at NAPA about this and they said I didn't need the in
> line resistor, but I don't know. I'm going to call another local NAPA
> store and see what they say about this.
>
> Anyway, I really appreciate any and all input from anybody on this list.
>
>
>
> Carl Szabelski
>
>
>
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