I am working on 4 KW coils for a customer. They are the newer type. They all look to have been rebuilt at some point, new capacitors and points. The first one I checked no issues, cleaned and gaped the points and set to 1.5 on the HCCT. The next two same thing but they seem to want to increase draw, going from 1.5 and moving up as volts increase. The 4th; the points that had been installed were really abused so installed new points. I can and did get it set for 1.5 amp draw and could only get it to fire using a spark plug. I did a little more work on it but will only jump an 1/8" gap when just using the HCCT. Any more gap then that, gets very inconsistent, random fire at the 16 points. All the coils checked out as far as readings go (2edary about 2800-3000, primary about 4 and capacitors jump and settle back as should checking both ways). My guess is this has been an issue on the 4th coil in the past re the abused points.
Any ideas? Or is this one coil just problematic?
A couple of possibilities. First, the HCCT can exhibit missing sparks if the spark gap electrodes get oxidized. Try cleaning the rotating electrode and spark ring with scotch bright to remove any oxidization. If the problem still persists and only with that one coil, then the problem may very well be that one coil was operated with an excessive spark gap which caused a breakdown of the wire insulation and arc internally. This internal arcing can then occur well before spark jumps the spark plug gap while under compression preventing normal operation. Unfortunately, there is no way to fix the coil if this is the root cause. A third possibility is a defective capacitor. That could cause excessive point arcing that can make the point contacts to appear "abused" and prevent the coil from firing spark properly. Have you checked the capacitor for proper value and leakage?
Does your customer have a working magneto ? Setting amperage draw at 1.5 av. amps works better for battery operation.
1.2 - 1.3 av. draw better for magneto ignition
It is just the one coil having issues. The other 3 fire fine when tested on the HCCT at about 1/4" spark gap. The only test RE the leakage I can do is set the meter for high resistance reading and check. It ramps up then drops down the same values/readings as all the other three. There is little or no sparking at the points. Abused points = not meaning the contacts, the points have been twisted bent and tweaked in the past trying to get the coil to work. I am getting a reading on both the primary and secondary windings and have not been able to find any opens in any test where they should not be.
My money is on internal arcing. It's not an open and not REALLY a short. It's more a matter of breaks in the insulation (Lacquer, I'm guessing) of the thin secondary wire and when the voltage builds, the
current jumps through that opening in the insulation to a convenient ground (Core maybe?). This is all before it builds enough to jump the 1/4" gap of the HCCT.
Ok we will go with that. Thank you everyone.
Someday I will set the HCCT where I can read the gauge and see the full circle of the spark rings! I have it setting too low to see the gauge directly. I am setting the draw for 1.2/1.3 amps. I was reading the mark between the two longer ones as 1.5. LOL
Back now to watch the tar melt.
Mine is an Allen. It doesn't even have a volt meter. Ammeter only. I must admit, I have turned off the lights before to makes dang sure I wasn't missing any "Missing" sparks.
I have a motorized HCCT, strbo-spark and ECCT with the computer program. The coil adjusting tool that I think does the best job of adjusting coils by far is the ECCT. It makes coils easy to adjust by giving you all the information, current, spark timing, spark strength, cap checks,etc. It even tells you when you need to adjust the cushion spring or the lower point tension and it tells you if you need more or less tension. This also can be done while checking the coil at various rpm's. It does a lot more than I mentioned here. It is a modern tool that could never have existed in the model T days. JMHO
Question. Is the coil giving you troubles one of the later ones with the iron core made of flat pieces of steel stacked into a square shape? (As opposed to a bundle of steel rods/wires?)
I have heard that they are sometimes not reliable, even if they test good and are "properly adjusted". Something to do with poor quality of windings in the coil itself. I do not recall if it was the primary or secondary coil.
Yes Wayne newer style with flat bars. I have read the info that they are not as good. Somewhere I picked up they were better on battery. Could be as most magnetos when they were were non-op.
In this group of 12 all were the flat bar style. The first 4 went fine, the next group of 4 only could save 1 the other 3 bad windings off the bat. This coil was last of that group I checked. The other 3 in this group got settled right off, so the one I as asking about was the very last one. Go figure.