later model 78 amp alternator?

[DaveS]

Hey guys,

i have a ''74 Plymouth Duster

i have a round-back alternator on it right now, but one with the 2 field connectors.

i have seen a new 60 amp alternator on rockauto

but i also saw a 78 amp model a few years later

is it possible for me to put the 78 amp model in my Duster? they're both squarebacks

for the couple bucks of difference i get 18 extra amps, sounds good to me!

also, isnt it weird for a 74 duster to have a round back alternator? werent the round backs discontinued somewhere in the early 70's?

 

[skykeith]

The 78 amp alternator will fit on your Duster. If you buy a 78 amp alt. make sure it has the narrow stator gap between case halves or it ain't a real 78 amp.

 

[BillGrissom]

isnt it weird for a 74 duster to have a round back alternator? werent the round backs discontinued somewhere in the early 70's?

Member 67Dart273 had several posts discussing this. During the transition to the electronic Vreg (1971-72?), some factory cars apparently came w/ round-backs w/ the "isolated field" (2 spade terminals). Also, rebuilders have done their own thing, and selling them w/ isolated field is most general if installers know to ground the extra field connection if the early Vreg.

A 78A alternator will only help if your 60A isn't keeping the battery charged over a week of driving. Otherwise, 60A is probably fine if the factory setup - i.e. no added electric radiator fan or mega-boom audio. The downside of higher amp is your wiring and dash ammeter may not appreciate it, as you get that high surge after each starter use. If you must drive 4 miles to recharge after each start, rather than 3 miles, it doesn't appreciably degrade your driving experience.

 

[DaveS]

Follow up!

i bought the 78 Amp squareback alternator!

bolted it in together with a fresh VR.

needle is smack dead in the middle of the ammeter now, all the time!

battery is basicly only for starting now. i can run all the things at idle, and the engine wont jump and stutter and my radio wont keep dying out anymore

i now have spare amps for other electrical projects

 

[rustytoolss]

Old thread....what year/model had the 78 AMP alternator ??? Thanks

 

[67Dart273]

CAVEAT. THERE IS NO WAY I would install one of these without doing some sort of WIRING UPGRADE. There are many many posts on ammeter/ bulkhead connector failure

"Ma" knew this was a problem which is why Mopar implemented the so called "police / fleet/ taxi" wiring mods for optional 65A alternators, AND WHY cars later (starting with some of the early 70's "big girls" like fury) ---went to an external shunt ammeter, which greatly relieved the bulkhead connector of high current, and ENTIRELY relieved the ammeter

 

[townsend]

Since most alternators on older cars have been replaced over the years, 78 amp alternators can be found on Mopar's from the 60's thru the 80's. The 78 amp alternator was introduced in 1982 on rear wheel drive cars.