Ignition coil.....Rusted Junks recent post

[Charlie ny]

Well I'm getting no where fast on the Advance Auto/Carquest pt# for an internal
resistor coil. I quoted a coil # I've used without a resistor, 52-1902, for-
ever. An online search says this coil requires an ext resistor. My human
contact at Advance/Carquest says his book tells him 52-1902 has an
internal resistor. The new Advance/Carquest # is E 5 P. Primary resistance
1 - 1.4 ohm.....secondary resistance 5.5k - 9.5k.
OK guys bail me out.
Charlie ny

[rotorwrench]

I wished I could Charlie.

Things are changing in the auto parts world. It seems to be getting harder to find anything for the older vehicles. After Standard Motor Parts bought Echlin's parts line, I've noticed that they still have the Echlin parts catalog but they took all the pictures out. It's hard to ID that stuff unless there are pictures. I'm just glad I still have a copy of the older catalog. The problem is, how much of this stuff will Standard continue to make and where will they out source it? I still remember Bumper to Bumper auto parts and how long has it been since they went bye-bye. NAPA seems to be dropping stuff too and their on-line system is not geared well toward the older stuff.

[Rustedjunk]

Should I check with Bob Drake or Dennis Carpenter?

[Ross F-1]

I wouldn't put much faith in what the catalogs say about internal/external resistors. Just go by resistance, if they bother to list it. When mine burned out I took my VOM to NAPA. The helpful guys there narrowed down my search, and I confirmed with the VOM.

I'm confused Charlie, do you want one with 1.1 ohm? If so, NAPA Echlin IC10 fits the bill. Not cheap. They offer cheaper ones but I don't know their specs.

[john in illinois]

Bosch coil primary resistance 3.5 ohms with a Fluke meter.Just reallized you were talking about 6 volts. Ignore Bosch post.

John

[JSeery]

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Originally Posted by Charlie ny

Well I'm getting no where fast on the Advance Auto/Carquest pt# for an internal
resistor coil. I quoted a coil # I've used without a resistor, 52-1902, for-
ever. An online search says this coil requires an ext resistor. My human
contact at Advance/Carquest says his book tells him 52-1902 has an
internal resistor. The new Advance/Carquest # is E 5 P. Primary resistance
1 - 1.4 ohm.....secondary resistance 5.5k - 9.5k.
OK guys bail me out.
Charlie ny

All coils have some internal resistance. If it specs out at 1 - 1.4 ohms it would require an external resistor. If you use 7.0 volts, then 7.0 / 1.0 = 7 amps & 7.0 / 1.4 = 5 amps. Both why to much current through the points. Coupled with a 1 ohm ballast resistor, it would end up 7.0 / 2.0 = 3.5 amps (about perfect) & 7.0 / 2.4 = 2.9 amps (a little of the low side, but should work).

[27TV8]

Hello. My Bosch coil p/n 0 221 119 027 has 2.7 ohms does this mean it has an internal resistor?
I am running 12 volts on my flathead.
Thomas`

[JSeery]

It means it has 2.7 ohms of internal resistance and would require somewhere around a 1.3 ohm ballast resistor.

[27TV8]

Great! many thanks,I will use a 1.2. I have one that is a white/gray block.
It looks ceramic? That will be my job after dinner.
Gotta get this thing going,summertime!
Thomas

[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.

[Charlie ny]

JSeery,
Thanks so much, I hope Rustedjunk has been keeping up with this foray
into the spark.
I'm thinking this E 5 P coil and a little old Ford resistor is at least one
valid answer to his original question. I know that these parts are available today
and if it means anything the coil is manufactured by/for BORG WARNER to their
specs, probably off shore.
Again many thanks to everyone for helping to bail me out !
Charlie ny

[donald1950]

NAPA part for 6V internally resisted coil is Echlin ECH IC7

http://www.napaonline.com/napa/en/search/?text=IC7

[JSeery]

Originally Posted by donald1950

NAPA part for 6V internally resisted coil is Echlin ECH IC7

http://www.napaonline.com/napa/en/search/?text=IC7

I didn't see a resistance listed for that coil, but it is specified for the 50s era Fords, so assume it is some where in the 2 ohm range. Any idea what the specifications are?

[JSeery]

I did find this on another post:

NAPA IC-12 Echlin 2.1 ohms primary, 8.9 ohms secondary

NAPA IC-27 Echlin 2.2 ohms primary, 6.38 ohms secondary

[donald1950]

the NAPA IC-12 & IC-27 are both 12v units and the IC-12 uses a ICR13 resistance unit..

i have a 2001 NAPA Echlin ignition & electrical systems book that specifies voltages and applications but for coils does not give resistance values......

the IC-7 is a replacement for a bunch of different 6 volt cars from 1928 thru 1955.

IC-8 was Ford & Merc specific but is no longer carried by NAPA and references to IC-7

i have an IC-7 on my 1953 ford car and it preforms without any problems...

[Bored&Stroked]

Great stuff guys - lots of good information on this thread, THANKS!