[AT] Questionable ignition coil

[Cecil Bearden]

I have a couple of old Sun distributor testers.  I check coils with 
them.  You can tell if the problem is with cranking or high speed.  I 
had a 6cyl 292 chevy that would cut out above 2500 rpm.   I had checked 
all the valves,  rebuilt the carb, replaced the points etc.  I put a 
"new"rebuilt distributor on the sun machine, and found that the 
distributor shaft was worn and with the new bearing it had a clearance 
of nearly 0.010  At 2000 rpm it started to oscillate.  I took it apart 
and found that the distributor must have been in a watery junkyard for 
years.  I took apart 3 distributors and ended up building up the wear on 
one shaft, then building a bushing out of a piece of Nylatron. Nylatron 
is a type of nylon that is impregnated with graphite.  I use it for a 
lot of bushings.  I bored the distributor out and replaced the top 
bushing with nylatron and the bottom one with brass.  By honing, I got 
the top of the shaft to 0.000 side movement, and the bottom with the 
gear to 0.005in...  Then I set it back up and tested the coil firing.  
This time the coil worked fine up to 5000rpm until I set a hair dryer to 
warm up the coil. With a infrared temp gauge at 140 deg, the coil would 
break down at 2000 rpm.  This time I tried an Accel Super Street/Strip  
coil 45000V, it would fire a 1/2 inch blue spark up to 6000 rpm.  I 
installed the distributor and coil in my old winch truck, and it had 
twice the power as before.
Cecil

On 11/5/2019 7:19 PM, Gilbert Schwartz wrote:
> I would like to try and delve into the wide knowledge and expertise of 
> the members within ATIS.
> 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.
> 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.
> I appreciate anything you can tell me.
>
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