Charging circuit - reduced load on ammeter circuit

BillGrissom said
67Dart273 PM'ed me about this thread as he recalled mine linked below. The dual diodes allow your dash ammeter to still work at lower currents, but shunts progressively more current straight to the battery at higher outputs. The ammeter is intended to read all current flow in and out of the battery, except for underhood loads (starter, horn) or special cabin loads like convertible motor or spotlight.
Modernized Engine Wiring | For A Bodies Only Mopar Forum

1963 and 1965 have the dedicated buss-bars which 67Dart273 shows. 1965 is better since it has more terminals. In 1964, they moved the large IGN and BAT wires to regular 57 terminals, which might have caused melting issues (familiar?), so apparently walked that back in 1965. In 1966, they moved the wiper motor into the engine bay, so added a 3rd terminal row and put IGN and BAT back to spade terminals, I recall bigger ones but not big enough (hence these hacks). I changed my 1964 Valiant to a 1965 bulkhead from a Fury. I had to cut the square opening ~1/8" taller to fit.

Thanks Bill. For those getting bogged in the convoluted "discussion" in that thread, the gist is that you use those diodes back to back across the ammeter, WHY?

Because if you BYPASS the ammeter with wire it is useless. If you want to do that and use a voltmeter, fine, that is OK too. But if you use those diodes, they have a point at which they do nothing. Because they are doing nothing, the ammeter reads NORMALLY. When the ammeter read more and more current, at some point the voltage drop across the meter becomes great enough to turn on one of the diodes, depending on which way current is flowing. (charge or discharge) This then forms a parallel path across the ammeter which limits the current through the thing.