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<p>I had an 80 model Suburban with 350 and GM HEI coil in the cap.
I had completely tuned it up and took a trip to Denver from OKC.
I noticed that at idle, there was always a sputter about every 10
seconds when warm. I checked everything, changed plugs, still
had sputter. The coil was an O'reilly house brand. I took it
back, but no exchange on electrical parts. I put the original GM
coil back in and it ran fine for another 5 years and another
engine until I retired the vehicle. <br>
Cecil<br>
<br>
</p>
<div class="moz-cite-prefix">On 11/6/2019 11:17 AM, Stephen Offiler
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAP6upcjp5kHDwo0iMdkWDoKq-+Cv8c7FCqcdQigx1_b5VBvb1w@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">Voltage drop test only works with current flowing.
In the case of testing the ignition primary circuit, points must
be closed. Voltage drop across coil depends on whether there's
an external ballast resistor in the circuit. If no resistor, a
good drop across coil primary terminals is slightly less than
battery voltage. But with a resistor, some of the voltage drops
across the resistor and some drops across the coil. I'm not
sure I can see how this test will tell you much about the health
of the coil, frankly.
<div><br>
</div>
<div>SO</div>
<div><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Nov 6, 2019 at 11:16
AM Spencer Yost <<a href="mailto:spencer@rdfarms.com"
moz-do-not-send="true">spencer@rdfarms.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 dir="auto">
<div>Sorry to reply to my own message, but I forgot
something. Also check voltage drop. Going into the coil
from the ignition switch, you should see battery voltage.
For instance if your battery is putting out 6.2 you should
see roughly 6.2 going to the coil. On the other terminal
end of the coil, there will be a slight voltage drop.
However on my bad coil with the Pacer voltage had dropped
all the way to 3.7 from 6.3V. Can not remember what a
good voltage drop is. Surprising large if I remember
right, but not 50%. Maybe I’ll run to the Pacer a little
later and see.</div>
<div><br>
</div>
<div>I don’t know electricity or electronics well enough to
know how or why that occurred with reasonable resistance
readings but that measurement was the only out of range
number I got.</div>
<div><br>
</div>
<div>I got that little tip from Brice Adams and what was the
final straw causing me to get an exchange rather than just
continuing to run on the old one.</div>
<div><br>
</div>
<div>Spencer</div>
<div><br>
<div dir="ltr">Sent from my iPhone</div>
<div dir="ltr"><br>
<blockquote type="cite">On Nov 6, 2019, at 11:03 AM,
Spencer Yost <<a href="mailto:spencer@rdfarms.com"
target="_blank" moz-do-not-send="true">spencer@rdfarms.com</a>>
wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">With an ohmmeter across the two screw
terminals, test resistance. Then test across negative
and the coil wire socket. Make sure you don’t have
zero or an infinite reading on either. Any other
reading is highly coil specific and hard to
generalize. I usually see 1-9ohms depending on which
of the two tests, voltage, brand, age, etc.
<div><br>
</div>
<div>However, having said this, I find the tests
generally useless as most coils fail on load and
heat and these tests do not rule out these issues.
For instance I once had a Farmall A coil that would
die when hot but tested fine on the bench. A new
coil and the tractor purred all day long for another
year or two till I sold it.</div>
<div><br>
</div>
<div>Another note: about two years ago I gave the
Pacer a tuneup. Would hardly run. I couldn’t
figure it out until, out of frustration, I put the
old coil back on. Ran great. The new coil tested
fine. Fortunately I had bought the coil from Napa
and they exchanged it. The second new one worked
fine and I am still running on it. So you can get a
bad coil out of the box in these days of poor
quality analog ignition components.</div>
<div><br>
</div>
<div>I’m sure others more knowledgable will jump in
with additional advice.</div>
<div><br>
</div>
<div>Spencer</div>
<div><br>
<div dir="ltr">Sent from my iPhone</div>
<div dir="ltr"><br>
<blockquote type="cite">On Nov 5, 2019, at 8:19
PM, Gilbert Schwartz <<a
href="mailto:vschwartz1@comcast.net"
target="_blank" moz-do-not-send="true">vschwartz1@comcast.net</a>>
wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">
<div
style="font-size:12pt;font-family:helvetica,arial,sans-serif;color:rgb(51,51,51)">
I would like to try and delve into the wide
knowledge and expertise of the members within
ATIS. <br>
Is there any acceptable method of determining
if an ignition coil is good short of
installing it on a running engine. Our 1949 AC
G would not start a few days ago after being
parked for a short period of time. A quick
observation determined the contact points were
beyond use. I went to the local auto parts
store and was advised I probably should
replace both the points and of the condenser
because they felt like that condenser went
first and it caused the points to burn up.
With this information I also purchased a new
coil even though I wondered if the coil was a
bad. </div>
<div
style="font-size:12pt;font-family:helvetica,arial,sans-serif;color:rgb(51,51,51)">
Bottom line; Is there any way to bench test a
coil? We have several used coils laying around
here of questionable viability. I would like
to pitch them if they aren't any good. <br>
I appreciate anything you can tell me. </div>
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