Correct Alternator Size

[Mark73mach1]

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

 

[Doug The Dog]

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

 

[Mark73mach1]

Thanks Doug. I do not have power windows or rear defroster

 

[midlife]

I don't have any information other than what's in the FSM. Sorry.

 

[Mark73mach1]

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

 

[midlife]

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.

 

[c9zx]

The assembly manual for 1972, dated 04/17/1972, shows 42 amp for Mach 1 302/351 no heated backlite or A/C. Chuck

 

[Mark73mach1]

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

 

[midlife]

It changes it a bit...if in doubt, go for the bigger alternator.

 

[Mark73mach1]

OK Thanks Randy

Mark