Help Junkyard coil for HEI distributor?

KitCarlson said

... The damage danger: it only takes about 3ms to charge the coil fully. In the long term the only current limit in coil is the resistance, that is about 0.5 Ohms. At 12V, the current would be 24A, in a fraction of a second. Since human reaction is typically 50ms, that is 0.05 seconds. So if you want to test, be quick ...

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If true, then I would have damaged a lot of coils (but didn't). I usually ground the negative lead for >1 sec before releasing (thus getting a spark). If 24A flows, the primary coil dissipates 288 W of heat (assuming a full 12 V on coil+). This will overheat it, but it takes minutes. For comparison, a hair dryer is ~1000 W. In continuous running, you do need to limit the recharging time between each spark (i.e. "dwell"), which HEI modules do with smart electronics, and most coils only need 10 msec or so to charge up. The 1970's Mopar ECU's were just a transistor w/ no smarts so didn't limit dwell time and thus still needed a ballast resistor as a kludge, as did the earlier points.

I suspect that the P.O.'s coil test failed because he didn't ground the body (or electrode) of the spark plug he was using. Most official spark testers come w/ an alligator clip to attach it to BATT- (or engine block). The later "HEI distributor doesn't work" conclusion might have been from using the HEI distributor plus an external HEI module, as TrailBeast was smart to ponder that possible FU. The ready-to-run HEI distributor has an internal HEI module, so doesn't need or want an external module. You wire it straight to the coil (hence the name). I don't know where they source that HEI module. It is different than GM's 4-pin one, but probably functionally equivalent. No reason you couldn't install a GM one if you could work it under the cover. I plan to install the better GM 8-pin and hack openings in the cover for it (or since I got a milling machine, maybe purty holes).