In my ongoing quest to "fix"everything possible before I start rebuilding my webers, I figured I'd check out my coil today. I read an online article that said it's better checked out of the car, than in, and gave instructions that have me needing the resistance specs (which Haynes doesn't list).

Then, I started wondering why there was a spare (used) coil in the trunk. The Bosch coil currently in the car has two numbers on it. They are:

0 221 102 076
0 222 905 115

The spare coil lying in the trunk is:

0 221 119 009

Any insight here is appreciated as always...don't know what I'd do without y'all!

0 221 102 076 = VW 022 905 115 B ... All 914 models

0 221 119 009 = Porsche 928 602 501 00 / VW 059 905 105 B, fits BPM Oceanic, Vulcano 450 / 375, V12/570, V 12/620 S

0 22 905 115 doesn't come up in Bosch ESI .. no information

If it fits a 928, don't use it. It's made for Bosch electronic ignition, not points or aftermarket point replacement. The Cap'n

Thanks.

Thanks. Any idea where to find resistance specs on the stock coil?

Between 1 and 15 - 3.4ohm
between 1 or 15 and center 6.8kohm,
hence 2000 : 1 ratio, 12v in, 24,000 volts out -
and stay away from the 928 coil - that puts out around 50k - at least in my 928!!!

Are you saying 3.4 ohm for the primary coil (between the two male posts), and 6.8k ohm for the secondary coil (between the center and the male plug)?

exactly -

Between 1 and 15 ( male posts) - 3.4ohm
between either post and center 6.8kohm,
hence 2000 : 1 ratio, 12v in, 24,000 volts out -
and stay away from the 928 coil - that puts out around 50k - at least in my 928!!!

Thanks...much clearer. The article talks about the coil needing to be within the specifed range. How "off" do you think either of those specs can and the coil still be acceptable?

I would say 3 min- 4 max ohms on the low side, read with a decent digital meter, and the high should be enough to get over 24k volts. I do not think you have a coil problem, but i have been wrong before!
A coil failure problem is more likely to be a dead short ( low side due to shorted points frying the coil) or open circuit than a change in base resistance. The output side cannot generate any voltage unless the points are opening and closing, if they stay closed the coil overheats and fails. If you have a short on the high voltage side it can fail, but less likely.
Have you done the water spray test on the plug leads to see if they are breaking down - sometimes called the firefly test?