Testing a coil

[preS]

I have a black coil for a 3 pin CDI that a list member is interested in, but I don’t have a car to test it in use.

Is it possible to bench test it? If so how and what should the readings be?

Thanks,

Richard

[pocketscience]

You can bench test it with a multimeter. Set it to resistance (Ohms) and you should get 0.4-0.6 Ohm on the primary and 650-790 Ohm on the secondary.

[SIMI BOB]

Pocket, can you be a little more specific on which terminals to put the leads. terminal 1, 15, main output lead? Guessing that the black lead would go to the body of the coil?
Thanks, Bob B

[pocketscience]

Primary is measured across the two outer terminals, secondary between main output and one of the outer connections - shouldn’t matter which, but measure both to be sure they are consistent.

[pocketscience]

Here’s an old coil. Still pretty close to spec but I replaced it as a matter of course when replacing a bunch of other stuff! You can see the reading between both outer terminals and the main is the same (723kOhms), and the primary is 0.8 Ohms.

[SIMI BOB]

Thanks so much for the reply. I am sure that helps a lot of us out here.
Bob B

[zenithblue71T]

Pocketscience, I did this today since I have no spark on my 71T rebuilt to S with carbs. I have a 2 year old Bosch coil, 901.602.502.01, pertronix pointless ignition, Bosch dizzy and Bosch CDI. I tested the coil as you described and found the following readings: I'm getting 1.2 on the primary and 165 on the secondary. What do you think?

[pocketscience]

Did you test it out of the car? Or at very least disconnected electrically from the car? The secondary reading sounds very wrong.

[zenithblue71T]

Nope, Tested in car with car off. I will pull and test and again. Thank you sir!

[zenithblue71T]

Pulled the coil Pocketscience and got the same results. I’m going to have CDI rebuilt and will replace the coil.