Ignition coil.....Rusted Junks recent post

[Charlie ny]

JSeery many thanks ! Your statement regarding all coils having some internal resistance
and Ross's post about taking his VOM with him to NAPA filled in a lot of blanks. The 6volt
E 5 P coil (which is the new # for 52-1902) from Advance Auto/Carquest actually measures 1.3 ohms. My stash of genuine
Ford ignition resistors on average measures .8 ohm each.
Am I in the ball park with the E 5 P coil and a Ford resistor? I think I am.
I guess I've been somewhat fortunate running this coil for so long without a resistor
with no apparent problems. I will mention this coil is on my shop test motor and
the motor is not required to perform work in the strictest sense.
I have certainly learned a lot in the last two days.
Charlie ny

[JSeery]

Originally Posted by Charlie ny

E 5 P coil (which is the new # for 52-1902) from Advance Auto/Carquest actually measures 1.3 ohms. My stash of genuine
Ford ignition resistors on average measures .8 ohm each.
Am I in the ball park with the E 5 P coil and a Ford resistor? Charlie ny

You are looking for something in the ballpark of 3.5 amps across the points. The calculation is:

Volts / Resistance (ohms) = Current (amps)

Now just plug in the numbers. A 6v battery at rest should be around 6.4 volts (I just picked a number, check you battery if you want a better number) and under charge with the generator/alternator charging would be around say 7.4 volts.

Your coil is 1.3 ohms and your resistor is .8 ohms, so total resistance is around 2.1 ohms (1.3 + .8 = 2.1).

So the low value would be: 6.4v/2.1 ohms = 3.0 amps

And the high value would be: 7.4v/2.1 ohms = 3.5 amps

Keep in mind that this involves approximations, but should give you a fairly good idea of where you are. Your combo looks good to me.