I relocated the battery to the spot of the spare. I ran 1/0 gauge wire to the starter and for the ground and welded a 3/8 stainless bolt to the frame rail for the ground. The positive cable is 13' long while the ground is 32" long. Someone told me that stainless is the poorest conductor out there but when I measure volts (12.54)at the shut off switch to ground by the battery and then measure from the common positive and common ground by the passenger shock tower, I get a reading of 12.51 at the front of the car. That doesn't seem like much of a loss. Do I really need to run another cable for the ground up to the motor?

 

It isn't really necessary, but if I were you, I would do it. The steel in the frame is OK but it isnt as good as a copper cable and you will get some voltage drop at all of your wire runs and connection nodes anyway, so minimizing that is key to having a trouble-free electrical and charging system. If you have too much voltage drop, it will be most evident when you are starting the car because that is when you are using the battery and it will be drawing several hundred amps, making any small resistance a higher voltage drop than you measure with an ohm meter. It is also important for the ignition system which, don't forget, is 20,000+Volts and needs a good ground to the power source and engine, although it is really running off the alternator after the engine has started, and not the battery.

 

I may as well. I put the 1/0 gauge wire in to be on the safe side so I'll run another up to the ground. Probably good insurance anyhow with MSD 6AL ignition