Testing a coil

[fng]

I have gathered 3 different coils in last few months and was wondering if there is anyway to test one to see if it's good or not?

[fishtail]

Put your tongue on the output wire.

Scott

[kwai]

or you could try reading the tune-up section of the manuals for the procedure to check the coil.

[kwai]

Or you could search for this thread using "coil resistance"

resistance specifications for the coil?

[kwai]

Or you can do this.

Check ignition coil primary winding resistance. Set ohmmeter on 10 ohm full scale range. Connect probes to positive and negative terminals of coil. Primary resistance should be 4.26. 4.9 ohms. If ohmmeter indicates 0 ohms or infinite resistance, replace coil. Check secondary resistance from coil primary terminal to tower Resistance must be from 12090 to 13910 ohms. If resistance is not within tolerance, replace ignition coil. Install distributor cover assembly

[fng]

Cool, thanks.

[militarypotts]

fng, I think the last post is your best bet, and safest.

[fng]

Huh? I was just going to touch my tongue to it....just seemed easier than getting out all those wires and having to read all those big numbers and stuff.

[militarytrux]

Just went through this practice myself with 3 coils. One of the coils was brand new in the box and the other two were used, one I knew worked and the other one was not working as far as I could remember.

The process described here

Check ignition coil primary winding resistance. Set ohmmeter on 10 ohm full scale range. Connect probes to positive and negative terminals of coil. Primary resistance should be 4.26. 4.9 ohms. If ohmmeter indicates 0 ohms or infinite resistance, replace coil. Check secondary resistance from coil primary terminal to tower Resistance must be from 12090 to 13910 ohms. If resistance is not within tolerance, replace ignition coil. Install distributor cover assembly

yeilded three different results, even the brand new coil was not in the range listed above (go figure) anyway I got the truck running with the new coil and then swapped each of the old coils and low and behold the truck fired right up with each of the old coils and ran the same with all three. I ended up keeping the new coil as a spare and have been running the old one for a few weeks now trouble free.

[militarypotts]

To the best of my knowledge, coils are a problem because we can't seem to get quality ones anymore. When I see a coil that's chrome plated, I know we have problems. Is their anywhere to get new quality coils for our trucks? Is their a coil out there that can replace the original?