I JUST GOT MY 51 F-1 THE SYSTEM HAS BEEN CHANGED TO 12V. IT HAS THE ORIGINAL 6V HORN. CAN IT BE USED WITH 12V OR DOES IT NEED TO BE STEPPED DOWN TO 6 V SOMEHOW?

 

the 6 volt horn will work with 12 volts to it......until it stops working.
it may work forever, or burn out after one or two "beeps" it is hard to say, it really depends on the condition the horn is in.

 

I used 12 volt on my 53 for over twenty years no problem.

 

THANKS FOR THE INFORMATION 1970 SOMETHING AND JWC3

 

12 volts working in a 33 woody with out any issues. had the genie rewired for 12 v. changed all the bulbs, reused the 6 v horn and starter . if more info is needed http://www.vanpeltsales.com/ is a good source of flathead info
for a note you can put 12v on 6v wires but not the other way, 6v on 12 v wires will fry them fast