Awesome, thanks for the info!
Ill be removing the 2/0 cable from battery ground to block and use it to replace the smaller gauge, current, ground wire from battery to chassis. Also will be grounding the Holley EFI near the firewall where Ford originally grounded the EEC IV.
And while you're here what kind of/size fuse or circuit breaker do you recommend to fuse the main positive battery lead running from battery to front distribution block in driver fender? Have a 200A alternator if that means anything. Will be using a 200A Fuse in the alternator charging lead.
Also, any suggestion on to exactly where i should solidly ground the cable from battery to on my hatch? its currently just grounded to the floor pan right next to the battery from the previous owner.(pic attached)
Thanks again for the extremely helpful information!
Car wiring is not any different than other wiring, it is common sense. You have to fuse any wire leaving a high current source as close to the source as possible, and that fuse has to be be reasonably above the peak load current and safely below the wire current rating. This is so if that wire is shorted or overloaded the breaker or wire opens and does not cause a fire.
Holly, at least in my installation, fused at the ECU. That means the wire up to that fuse is unprotected.
You should use a similar or just slightly larger fuse or breaker back at the source. Either duplicate what Holley uses or go up just to the next step up in size.
If you use the alternator lead at the alternator, it protects the alternator. But that protection is actually sort of meaningless. If you get a reverse battery or some load fault the alternator diodes or field winding will usually pop anyway. I wouldn't remove the fuse, it isn't bad to use one, it just does not make the wiring safe.
The real place to protect the alternator high current feed is at the battery connection end. The battery can dump hundreds and hundreds of amps for a long time, whether the car is off or on. In a hard short it will run until the battery melts down, a wire burns in two, or the short burns open. This is why car manufacturers use fuse links where they up-tie a branch into a higher current feed.
Be sure you protect the wires at the SOURCE, and that between the protection an the source things are no where a wire fire would cause a car fire. The alternator is a source when running, so it isn't bad to protect there. It just doesn't do much unless the wire leaving the protection is rated way above the protection size. The real issue is the battery. It can dump 10 or 20 times what the alternator can. If you have a wire from the alternator to the battery the fuse at the alternator doesn't do a single thing to make you safer. It just might help the alternator, but it won't stop a fire at all. Any fuse or fuse link belongs near the battery ends any lines or line branches.