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Correct Alternator Size
#1
Randy,

What would be the correct alternator amp size for my 73 Mustang Mach 1, 351C-4V, FMX, non a/c. I'm not sure if it came with a 42 amp or 55 amp alternator.

Thanks Mark

Mark

1973 Ford Mustang Mach 1, 351C-4V, Ram Air, FMX, Wimbleon White
1969 Ford Mustang Sportsroof, 390-4V, T-5, Black Jade
1968 Mercury Park Lane Convertible, 428-4V, C-6 auto, Polar White
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#2
If your car doesn't have power windows or rear window defrost, (and you already said it doesn't have A/C), it would have come with the base 42 amp alternator.

-Travis

- Travis



I'm an analog man in a digital world.
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#3
Thanks Doug. I do not have power windows or rear defroster

Mark

1973 Ford Mustang Mach 1, 351C-4V, Ram Air, FMX, Wimbleon White
1969 Ford Mustang Sportsroof, 390-4V, T-5, Black Jade
1968 Mercury Park Lane Convertible, 428-4V, C-6 auto, Polar White
  Reply
#4
I don't have any information other than what's in the FSM. Sorry.
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#5
Randy, If I change from 42a to a 55a alternator what would be the pros and cons? I have a non a/c, non power windows an no rear defroster.

Thanks Mark

Mark

1973 Ford Mustang Mach 1, 351C-4V, Ram Air, FMX, Wimbleon White
1969 Ford Mustang Sportsroof, 390-4V, T-5, Black Jade
1968 Mercury Park Lane Convertible, 428-4V, C-6 auto, Polar White
  Reply
#6
No cons that I can think of; the only pro would be that if you are drawing more current than the 42a can provide, the 55a would provide it. However, Ford typically built in a 100% margin in their electrical budgets.

Remember, alternators only provide current upon demand: they cannot push current to the system.
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#7
The assembly manual for 1972, dated 04/17/1972, shows 42 amp for Mach 1 302/351 no heated backlite or A/C. Chuck
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#8
Thanks Randy and Chuck. I just remembered that I have changed my headlights over to halogen with a relay. Does that make
any differences?

Thanks Mark

Mark

1973 Ford Mustang Mach 1, 351C-4V, Ram Air, FMX, Wimbleon White
1969 Ford Mustang Sportsroof, 390-4V, T-5, Black Jade
1968 Mercury Park Lane Convertible, 428-4V, C-6 auto, Polar White
  Reply
#9
It changes it a bit...if in doubt, go for the bigger alternator.
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#10
OK Thanks Randy

Mark

Mark

1973 Ford Mustang Mach 1, 351C-4V, Ram Air, FMX, Wimbleon White
1969 Ford Mustang Sportsroof, 390-4V, T-5, Black Jade
1968 Mercury Park Lane Convertible, 428-4V, C-6 auto, Polar White
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