Bench testing a coil

[wpsrea]

Any one know of a way to bench test a coil? I have three laying around that I would like to find out if they are any good.

[gordr]

When I have had occasion to do this, I just put a short piece of sparkplug wire in the coil tower, then used a pair of clip leads to connect the coil to the battery. Run a clip lead from the (-) post of the battery to the (-) stud on the coil, and clip it on. Hold the free end of the sparkplug wire near the (-) stud on the coil, and just scratch the (+) clip lead against the (+) stud on the coil. You should have no problem getting the spark to jump 1/4"

If the spark jumps a quarter-inch in this test, the coil should work well enough to start an engine. Whether it breaks down under heat is another question. But this crude test should save you the frustration of trying to start an engine with a dead coil.

Gord Richmond, within Weasel range of the Alberta Badlands

[wpsrea]

Thanks Gordr

[laughinlark]

What Gordr said is true. I don't know about 6 volts, but with a 12 volt watch the color of the spark. Dull orange is getting weak, bluish is hotter, white is the hottest.

Gordon

[2R2]

Slow night around here....I am trying to bench test a few coils I have for my R2 Lark, which is still equipped with the Prestolite dual point distributer. Using an ohm meter, what resistance measurements should I be getting for the primary a secondary windings?

[Alan]

I like to see 1 1/2 to 3 ohms primary. And 20,000 + or -2,000.

[Bob Andrews]

One thing, if there's even the slightest sign of oil leakage, toss them.

[TWChamp]

My Model A's are also 6 volt positive ground, and I made a coil/condenser tester to check the Model A coils and condensers. It will check my Studebaker parts the same. I rigged up a relay to vibrate at a rate the same as the engine turning 2000 RPM, then clip on the coil and condenser to be tested.

Anyway a simple, quick bench test is easy by connecting the condenser to the two primary terminals, then connect the battery + to one primary terminal and touch the other battery wire to the other primary terminal off and on while holding the coil wire 1/4" from either primary terminal. You should get at least a 1/4" hot blue spark. My Model A coils give a good 1/2" blue spark. I haven't tested any of my Studebaker coils yet, but I'd expect about the same. The condenser is very important to a good spark. It does more than just keep the points from arcing.
T

[2R2]

Thanks to everyone who provided input! I'll be checking my coil collection on the workbench this weekend.