If you’re reading 6V at the coil on a 12V system with the engine off and the ignition switch in the on position, then you’re dropping 6V from the starter relay to the coil. That would indicate you have a ballasted ignition system which has a ballast resistor in the wire going from the relay to the coil. There should be a second wire attached to the + terminal of the coil that provides 12V during a start by temporarily bypassing the ballast resistor through the ignition switch when you start. The reason the new coil is marked 6V is because that’s what you need. The coil should only need 6V when the engine is running. Running at 12V will cause the coil to overheat and eventually fail. Applying 12V during a start for a short time doesn’t hurt it.<div><div><br></div><div>If you don’t have the second wire, then you probably have a coil with an internal resistor. That requires 12V to the coil at all times, 6V will be dropped internally through the internal resistor. Maybe the PO did some rewiring and left a ballast resistor in while putting in a coil with an internal resistor. If you do have an in-line ballast resistor and a coil with an internal resistor, then you have too much resistance and you’re dropping too much current going through the coil, which gives you a weaker spark. That may be why putting 12V directly to the coil makes it run better. You’re overcoming the extra resistance with twice the voltage.</div><div><br></div><div>The first thing you need to do is determine which type of system you have (ballasted or non-ballasted), and if you have the right coil (internal resistor or not). From looking at the wiring diagram I sent earlier it doesn’t seem to indicate you should have a ballasted system since it doesn’t show a second wire at the coil. But again, maybe the PO made some modifications?</div><div><br></div><div>Now if you’re dropping 6V at the starter relay, then the relay or the connection to the relay is suspect. That’s why I suggested testing the starter relay to see if you were dropping voltage there.</div><div><br></div><div>Once you have a definite idea of what type of system you have, it should make finding the problem easier.</div><div><br></div><div>Carl<br><div><br>On Thursday, August 26, 2021, John Hall <<a href="mailto:jtchall@nc.rr.com">jtchall@nc.rr.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
points, plugs, cap, rotor and coil are all new. I verified with my
50 year old parts book and it has the same part# for coil as what
online parts at Case is showing. The new coil has 12V on the
outside, but the bill had 6V. Box was sealed up, but it came from
overseas, so a lot of variables there<br>
<br>
Point gap was verified when I had the distributor off and plate out
so I could make sure weights were free and springs not broken.<br>
<br>
I had my voltage regulator with me yesterday. When I tried to check
at coil with engine running rough, it showed OL for whatever reason.
I've checked so much stuff lately that I'm not sure but I think I
got 6 and 12 volt readings depending on where the points were once I
shut the engine off. I tried checking the voltage with engine
running at the fuel solenoid for reference and it was floating all
over the place from 4 to 13.5V. This was observed with the engine
hot and running rough. With engine not running it holds steady a
little over 12. <br>
<br>
Last night I also found that the wire to the coil and the wire to
the R terminal on starter solenoid can read 6V (little less
actually) while the wire going to the fuel solenoid in the carb was
reading 12V.<br>
<br>
John Hall<br>
<br>
<br>
<br>
<div>On 8/26/2021 6:35 PM, Howard Pletcher
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-family:tahoma,sans-serif">It's
not unheard of, particularly since many of those parts now
come from overseas. To me, swapping with another if you can
find something to swap with would be the easiest way to prove
or eliminate that as a possibility. </div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Make
sure your points setting is close to spec and they are clean
as that would affect the ignition. Have you looked at your
plugs, not thinking that's the problem, but if they are fouled
or badly gapped, they could have an effect. You also might
run it until it heats up and needs the 12V to see if it still
shows 6V to the coil. If not, then it's somewhere else in the
circuit.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Many
of the other things suggested have no connection with the
ignition circuit. </div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu, Aug 26, 2021 at 5:12
PM John Hall <<a href="mailto:jtchall@nc.rr.com" target="_blank">jtchall@nc.rr.com</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div> Howard, you are leaning toward new coil and old coil are
both bad?<br>
<br>
John Hall<br>
<br>
<div>On 8/26/2021 3:47 PM, Howard Pletcher wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div dir="ltr">
<div class="gmail_default" style="font-family:tahoma,sans-serif">No, what he is
reporting is just what should be happening. With
the points open, no current is flowing through the
primary circuit and there is 12V at the + side of
the coil. When he bumped the starter and closed the
points, the current flowing through the resistor in
the primary circuit results in a voltage drop so
that there is now 6V on the coil as intended. </div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">The wire from
the starter to the coil does send 12V directly to
the coil, but this is only engaged while the starter
is cranking in order to produce a hotter spark for
starting and is not connected to 12V the rest of
the time.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">The fact the
coil seems to require 12V to its terminal when hot
points to an internal problem in the coil as
discussed by Dell in the Yesterday's Tractors
article.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Howard</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu, Aug 26, 2021
at 2:53 PM Carl Szabelski <<a href="mailto:c.s.szabelski@gmail.com" target="_blank">c.s.szabelski@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> By the way, I
believe it’s not the coil and is related to the
cranking motor. Especially since the voltage drops
when you bump it like you said. Something in the
motor may be partially shorted or corroded, causing
a voltage drop to the coil. The coil should always
see 12V whether or not there is a resistor, internal
or external. The resistor is essentially after the
coil winding and drops the voltage after the
winding, not before it. If the engine is running
fine when you directly connect 12V to the coil, the
coil is working like it should and is good.
<div><br>
</div>
<div>Carl<br>
<br>
<br>
</div>
</blockquote>
</div>
</div>
<br>
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