Model A fuse.

Generator output voltage varies with applied load. Higher load, lower voltage. That's why you have to readjust between day and night driving.

If you remove the fuse with the engine running, voltage will go up due to battery charge load being removed. But it will continue to run, perhaps damaging the coil from the higher voltage.

If a 30-amp fuse blows because of a short, then all generator output goes into the short. 0 volts at the coil - engine dies. A good thing, until you remove the short.



So if short is intermittent - possible issue I guess. Possibly would be hard on the condenser and points, possibly pop bulbs?
 
Right-wrong-or-indifferent, I used the starter mounted fuse for years. That was originated when a club member's tudor wiring started smoking. We couldn't get to the battery cable and remove it quick enough. Fortunately, while all the wiring was "toast", the tudor didn't catch on fire.

A few years ago, I put an inline fuse going to the lights/horn. It is less than the one at the starter, neither being 30 amp. Rarely do I drive at night so if there was a short ahead of the inline, I can drive home or get off the road.
 
Hey PalAl, what's that you got coming out of the oil filler tube?

It's an oil breather tube, it can direct fumes and blow by mist to the bottom of the car to help keep the engine compartment cleaner. Complete with flip top to add oil. Bratton's part # 9920
 
I consider the fuse modification a must have on any Model A. It is also a good idea to remove the fuse from the holder and stand it on its head at either end of the holder when finished driving for the day. This will remove power from all the circuits in the car except power to the starter, which is not normally a problem area.

Should there be a partial short circuit somewhere where the current draw is less than the value of the fuse, say it is drawing 20 amps and the fuse is a 30 amp. It will sit there and smolder long enough to light a fire. Removing the fuse will prevent that.

Tom Endy
I've been using a 20A circuit breaker for many years. Never have a problem with it. I also remove it when I'm parking the car for a length of time. Not only will it prevent any current drain from draining the battery, it's a great anti-theft procedure.
 
All Model A I have seen have a glass tube fuse mounted on the starter I replace all of these by wiring in a blade type fuse. The glass tube type fuses have a tendency to cause problems. do not understand your question about the ign switch? The starter is hot all the time are you wanting to cut the the starter through the switch?
 
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