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On my Dart I used a Napa alternator, it's a mopar "78 amp" unit from a Volare I think, here is a pic showing the part # and the RPM/output relationship. The RPMs there are alternator rpms. I don't recall the ratios, but I think once the engine reaches about 1700-1800 RPM (if memory serves), the alternator is spinning enough to churn out all 79 amps.
Cool chart. Too bad we don't have alternator output charts with engine rpms versus output for all the original Mopar, rebuilt Powermaster, Denso and CS140 alternators. All but the CS140 are notoriously weak at and just above engine idle rpm.
The CS140 altenator I ended up bolting right into my 1970 puts out up to 115 amps at low idle and potentially up to 200 amps above a fast idle with a nominal voltage of 14.4 volts. None of the other popular conversions mentioned even close to half this amount of idle output. Period!
Why did I install so much power? I added several power hungry electrical add-ons and needed the increased idle output, A/C, electric fuel pump, twin fans, power windows, headlight upgrades, line lock and MSD ignition. It's all fed from the engine compartment power distribution lugs, amp gauge is bypassed and the bulkhead modified. With everything on, it still has 14.4 volts at idle. Sweet!
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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