I am looking for some insight into an electrical system i am working on. The car is a 52 Hudson with a 6cyl 6volt positive ground system. It has a new pertronix igniter with a pertronix 1.5 ohm flamethrower coil. Using my TA100 meter, I am getting 17.10kv (17000 volts) out of the coil, but only 6kv (6000v) at the spark plug. New spiral wound 8mm plug wires, #1 wire ohms at .77. New cap and rotor. Ran wire to battery instead of switch to take that out of the equation. Is a drop in voltage over half normal or what else should I look for? Thanks!!
You may get a better answer than mine, but coils only output as many volts as it takes to jump the spark plug gap.....or short to ground....whichever is less.......up to the limits of the coil. For example, a coil capable of 50,000 volts may only produce ...well....as in your case 6,000, if that voltage will reach ground, hopefully at the spark plug gap. Ray
Do you mean 17kv out of coil, no load, simply out of coil tower...or under load, everything connected as it should be? If under load and plug wires are non resistor as you say that 11kv loss must be across the rotor gap inside cap. You didn't say, I assume car won't start or run? Based on the little information I'd check cap, rotor, timing. Sent from my SM-S320VL using Tapatalk
Yep, more resistance will cause more volts, up to the coil max. Close the plug gap and I'll bet you see even less voltage
I might use solid core plug wires and points (for now) with a 6 volt system. Or not worry about secondary voltage output anyway. Does the spark look good?? 6 volts doesn't leave a lot of margin, everything has to be right.
I wonder how you measured the coil output voltage. If you just measured from the coil tower to ground then there was no gap at all. If that gives you 17000 volts then I would plug the coil high tension lead back in and pull a plug wire from the distributor and test it there and see how much the loss is. Keep working down the line to the plug. I am a little curious as to what the readings should be and I don't know where to find out.
More info- The system has been changed to a pertronix igniter and coil to match. Pertronix says not to use solid core wires. I may have to switch back to points setup if all else fails. Car has been setting for 2+ years and not running. No attempt to fire or even backfire at this point. Even with starting fluid. 100 lbs compression every cylinder. Hudson had a weird way of checking timing, the marks are on the flywheel and not the front dampener, making the marks very hard to get to and see, right above the starter. I pulled #1 plug and used paper towel in hole, rotated until it popped up and am very close on the timing marks. Measured voltage with everything hooked up in place. Will do as suggested and pull the plug wire off the plug and check. Out of curiosity I will play with plug gap and check voltage again on #1. I suspected cap and rotor but changing them twice did not change the result. Reading thru all the replies, has got me thinking back to timing issue. The weakest part of a big six Hudson motor is the timing chain and bronze oil pump gear. Thanks!!
Did you take out the points, or was it already like that? I tend to try to get stuff working "as is" first, and point ignition is pretty forgiving about working. Lightly file the points if they're oxidized, be prepared to change out the condenser or coil if things don't work right away, and also spend time making sure all the other stuff is correct--compression, valve timing, ignition timing, fuel system, etc. My failsafe method of checking for sufficient spark, is to cut the side electrode off a new spark plug (doesn't really matter what kind of plug it is), and lay it on the top of the engine, and connect a plug wire to it. Turn on ignition, crank engine, see if it sparks. The reason for cutting off the side electrode is that it will need to jump a much larger gap than normal, which takes about the same amount of "spark power" as it does to fire a plug when it's in the engine, with compression.
Update on this project- (6cyl, 6volt positive ground 52 Hudson) Prier owner had put a Clifford 4br intake manifold on and a set of long tube headers. Have no idea what other mods or work he did as he passed away a while back and no records found. New owner had installed an Auto Lite 4br I went back to basics and back over the distributor, pulled it and bench checked the pertronix unit and it checked out fine. Checked the cap and rotor clearance, ok. Pulled the plugs and re-gapped to .037 for pertronix ignitor usage. Cleaned all plug seats with a small wire brush using a die grinder. Re-installed plugs. Turned motor to the TDC position using "pop" test. Pulled oil pump out to check bronze gear wear. (20% wear, checked against an nos one.) ok Used a bore scope to check cam gear -- ok Used a Hudson timing tool to install the oil pump back in and put the notched shaft in proper position for the distributor to go back in to and have #1 at the factory position. Checked for spark -- spark Shot some starting fluid in, no go Shot some non-ethanol in-- started hitting. Shot gas into the vent tubes to put gas in the bowels. (no gas line hook up) Started running and ran until out of gas. New owner came over and started adjust the 4b carb. In a few minutes the Hudson was running like a sewing machine!! Mike(new owner) really likes the Auto Lite carbs, very easy to adjust on the fly. Thanks everyone for your input!!
The Jalopy Journal
