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Old 06-10-2005, 04:12 PM
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Ignition Coil resistance Question

Hello guys, I just got a Accel HEI Super coil from a friend, naturally the first thing I did when I got home was clean it up, check the resistance and take my old napa replacement coil out and install the super coil.

my question is this, I found .9 ohms of resistance in the super coil in the primary (red wire to high tension and yellow to high tension), oddly I have seen these (this is the in cap super coil) rated at .5 ohm. but the strange thing is that my old coil when measured didn't even show continuity, and I checked it at least 5 times. yet my truck was running just fine, and I had plenty of power how can this be? am I missing something? where does the black wire go inside of the stock coil?

also the Super coil does not have the little black wire going to the laminated steel portion like the stock replacement coil, I found this strange, but I figured the connection to the laminations was made internally. however, with all the differences in both resistance and wires they both work in my truck

can any1 shed some light on this?


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Old 06-10-2005, 07:53 PM
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I couldn't tell you what the different resistance values mean but I'd advise you to keep the Napa coil in the dash, along with the tools you need to swap coils.

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Old 06-10-2005, 09:53 PM
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yeah I will put the coil in my truck. I already have enough tools in my truck to take my motor and tranny down to the bare castings in fact, I wouldn't hesitate to swap trannys on the side of the road ... lol

but this one really makes me curious, I have never seen anything like that before...

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Old 06-11-2005, 03:36 PM
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Turns Ratio

Doc here,

The differences in the resistances of the two Coils, is the Turns ratio..

Your Stock HEI Coil should read between 3000 and 6000 ohms Between "BATT"and The Center Carbon Element.....at about R x 1 K or auto range, at 12 volts it will draw about a half amp...(that is if I did the math right..and didn't slip a digit..) The "BATT" To "TACH" terminals should read 000 Ohms at R x 1 ohms OR Auto range...to each other, and 3000 to 6000 at R x 1 K ohms to the carbon element.

Your Super Coil, at .5 Ohms at R x 1 ohms....and at 12 volts will draw about 6 amps..and supply more of an inductive "Punch" across the Core windings of the coil (A Bigger Magnet)...or Cutting lines of force. (And depending on the Secondary Windings turns ratio..Deliver a Higher Inductive Output to the Plugs)

Two things I can advise, If your going Super coil..and you have a Fuse on the Coil wire (Some GM's have one in the FB) upgrade it to a 7~1/2 Amp Slo~blow, or a 10 standard.

Next upgrade your plug wires to good quality 8.5 MM spiral core wires..If you have standard HEI (especially older standard HEI ) wires, you'll find they will crossfire, and jump fire at the Boots..

You might also want to consider re~gapping the plugs to where it runs best between 45 and 60 thousands..you should be at 45 now...

Other than that, you should be all good...

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