I have read and re-read posts and articles about underhood wiring for my big block project. I am at a point where I think I have everything just about figured out, but I still have a few questions.

I have my starter installed like the MAD Enterprises Startm'up Kit. Basically one large battery cable going to the starter with a jumper wire from the large lug on the starter to the smaller S terminal on the solenoid. That one large wire is connected to the normally off side of the firewall mounted solenoid. The cable from the battery is connected to the other side of the solenoid, that would make that side normally hot. I then have the purple starter wire from the ignition going to the S terminal on the firewall mounted solenoid. I should also have a battery charging wire connected to the normally hot side of the firewall mounted solenoid as well, to charge the battery when the car is on. This wire will be from the new junction block that I installed that has the main feed from the alternator mounted there too, so that I have a constant 14 volts to that block when the car is on. The question then becomes, when the car is off, the junction box and all connections will be hot, since the battery charging wire coming from there is connected to the battery cable, right? Does this pose any risk of battery drainage or system failure?

Hopefully I am making sense and some of the electrical guru's will chime in. Please feel free to ask any questions if I didn't make sense. I could take some pics if needed.

Yes, it will be hot at all times. There is always a very slight danger whenever you have 12 volts hot with as much current as the battery can deliver, but this is why you either use a Maxi-fuse or fusible link in there to protect your car. (you could even use both if you're paranoid)

As for battery drainage, only if you have something "turned on" to allow current to flow. While you are going to be a little different in configuration, the basics of how you are set up is no different than most of the millions of cars on the road.

I think you'll feel a lot better once you get it all installed and working. You have a good plan, now make it happen. Post pics here first if you feel you need to before going live.

Steve

OK, so should I run a 10 gauge wire from the firewall mounted junction box to the hot side of my solenoid to charge the battery, and on that wire should I have any type of fusible link or diode to prevent the battery from sending power back to the junction box when the car is off?

Fusible link yes, diode no. You definately want a fusible link between the battery and the rest of the circuits. Diode will only flow one way so battery can't supply current when alt can't keep up which can happen at idle with lights and other accessories on. You also won't be able to start the car, no current flow from battery to ignition circuit. That's if I understand your wiring correctly.

Junction block and horn relay on A bodies is always hot. Just something you need to be aware of and take the necessary precautions when working under the hood.

OHHHH!!! OK, Finally, thanks, that helps out a bunch, I will install a fusible link on that battery charging wire to protect the system from a battery power surge or short. I read up on diodes, and your right, power only flows one way, so it would be impossible to get power to the ignition circuit with this setup. I got ya.

Thanks for the clarification and thank both of you for staying with my description of the wiring and understanding it.

You're welcome. If you're running a 10g wire from the battery to junction block you'll need a 14g fusible link. Only a couple of bucks at an auto parts store.

HAHA, you beat me to it, I was typing that question next, thanks.