several voltage regulator burn

I don't have any idea of the specs on that regulator, a few comments

12 something is not proper charging voltage. Depending termperature, voltage varies, but on a warm day, normal engine temps, charging/ running voltage after the battery has recovered from starting. should be 13.8--14.2

The why of your regulator problems could be.........

1...that there is a partial short in the alternator field winding, which absolutely can and does happen
2...that regulator may NOT be heavy enough to carry the field current of whatever alternator you are using
3...the alternator you are using may have been improperly rebuilt with a rotor which draws excessive field current, AKA out of a heavier duty unit than this one

You want to check that the VR power terminal is not seeing a voltage drop as this will cause over charging, and that the VR is actually grounded to battery NEG potential, which will also cause over voltage

To check this out, get the thing as close as you can to operating temp and the battery "up" and normal. Get the engine running at fast idle and run this test first with accessories off, and again with lights, heater, etc powered on

Stab one probe of your multimeter into the top of the battery NEG post, and the other probe HARD into the mounting flange of the VR to get through any chrome/ rust/ etc. You should read very little voltage, the less the better, and zero is perfect

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To check the power/ field circuit of the VR, turn the key to "run" with engine stopped. Stab one meter probe into the top of the battery POS post. Leaving all wiring properly connected, probe the IGN terminal of the VR. You will again read a little voltage and the less the better. If you read more than .3--.4V (3/10 of one volt) find out why. If your car is factory wiring, the usual suspects are poor terminals in the bulkhead connector, the igntion switch connector, the switch itself, and possibly at the ammeter. This voltage drop when running causes the VR to ramp up to make the IGN terminal 14V rather than the voltage drop it is seeing. THAT causes the battery to see higher voltage. If the VR is properly operating at 14V, then add that to the voltage you measure in both the ground test and this last test, and the total will be close to what you see at the battery.