[67johnny]

There are two wires coming into the battery junction block(not counting feed from pos. battery) located behind the battery on my 71 and the assembly manual shows a fuseable link on the black 20 gauge wire that I believe is lighting related but it does not list a rating! I was thinking about putting in a 20 amp breaker like I use on my trailer for the electric brakes but I am not sure if 20A is to big. Does anyone know what the factory rating for this black wire was? Thanks!

 

[John_Muha]

Generically the links are:
A 14 gage fusible link protects the 10 gage battery charging circuit.
A 16 gage link to protect 12 gage unfused wiring. Maybe near horn relay.
A 20 gage link to protect the 16 gage wiring maybe around the idiot light field wiring.
Two fusible links 20 gage protect the ammeter circuit.

 

[67johnny]

Thanks John! So on this 20 guage wire use a 24 gauge link? ... or being this is a lighting circuit can I use the 10A breaker and be safe?

 

[John_Muha]

The breaker idea sounds safe but you may run into some false tripping. Then again maybe not. The headlights draw a lot of current when they first turn on. If the switch is set on high beam, the breaker has a good chance of triping.

 

[Corey872]

I think I read somewhere that a fusible link will generally be 4 AWG sizes smaller than the wire it protects. The numbers John pointed out are right in line with that.