47-55.1 Wiring harness question

[TX3100Guy]

I'm finally getting around to running all the wires in my 1953 5-window. I have the full upgrade wiring harness from American Autowire. The question is, where have you located the two "Mega Fuses". I'm trying to find a suitable place to locate it that is convenient to both the alternator and the starter. Thoughts?

[dsraven]

the big fuses should really be placed close to the battery if possible. this is to eliminate the possibility of unfused lengths of wire. I have used the littlefuse holders close to the batteries, some will hold 2 or more fuses and have a rubber lid.
https://m.littelfuse.com/products/fu...81028hxfc.aspx

[Hcb3200]

i concur. Mine is right behind my battery out of the way, hidden and a short run of unfused wire. Not like these things blow on a regular basis. They are the last resort kind of thing when something gets shorted.

[youngrodder]

Originally Posted by TX3100Guy

I'm finally getting around to running all the wires in my 1953 5-window. I have the full upgrade wiring harness from American Autowire. The question is, where have you located the two "Mega Fuses". I'm trying to find a suitable place to locate it that is convenient to both the alternator and the starter. Thoughts?

I mounted mine to the front face of the front cab mount on the Passenger side as it was close to the starter and battery. Hard to see in the photos but it is behind the heater hoses. You can see 2 thick red power supply wires coming in from the top.

If you need a better pic I can snap one.

Marc

[TX3100Guy]

Originally Posted by youngrodder

I mounted mine to the front face of the front cab mount on the Passenger side as it was close to the starter and battery. Hard to see in the photos but it is behind the heater hoses. You can see 2 thick red power supply wires coming in from the top.

If you need a better pic I can snap one.

Marc

Thanks to all. @youngrodder this is where I will look for a location to mount the Mega fuse block. It seems like a good location near both the battery and the starter. Hard to see from the photo, but did you mount it on the frame? If you had to replace a Mega fuse, how hard would it be to get to it? Thanks!

[leegreen]

If you blow a 175 amp fuse it is probably not going to be a roadside repair so serviceability does not need to be set at a daily access level.

I have firewall mount battery, big wire to starter and not quite so big wire to a 80 amp manual reset circuit breaker right beside the battery, everything else feeds from there. I'm HEI, carb and mechanical pump, no amps, AC etc so not a huge current draw.

[youngrodder]

Originally Posted by TX3100Guy

Thanks to all. @youngrodder this is where I will look for a location to mount the Mega fuse block. It seems like a good location near both the battery and the starter. Hard to see from the photo, but did you mount it on the frame? If you had to replace a Mega fuse, how hard would it be to get to it? Thanks!

Yea, I drilled thru the face of the body mount and installed nuts on the backside to secure it. It could be accessed without too much issue. 6,000 miles so far and yet to have to mess with it.

Marc

[mr48chev]

Personally I would want the mega fuses a bit more accessable than what Youngrodder showed. All too often a short that causes one or both of those fuses to blow happens at an inopportune time and place in what often isn't the best weather. As for myself I really don't want to have to jack the truck up and slide under it to reach one of those fuses.

[dsraven]

I assume you will be running the pos cable to the starter and from there you will draw power for the circuits, correct? the same way chevy did it for years except you will use a pigtail cable from the starter over to your mega fuse pack instead of fusible links in the wiring connected to the starter terminal. if thats the case then you will want to mount the mega fuse as close to the starter as possible for the shortest unfused wire from the supply to the mega fuse.
another way to achieve the same result is to draw power for the mega fuse directly from the battery. the later model chevy trucks (mine is a 2015 and I just replaced the battery in early Jan so thats what sparked the thought) come with a battery cable terminal that has an extra lug on the side and that connects to a mega fuse holder connected right at the battery. you could draw power right from the battery that way. possibly an aftermarket supplier could come up with the correct style terminal or cable for your application needs since the GM cable is a little spendy. just a thought. or maybe you could come up with a good used cable and the plastic holder that fits the mega fuse thing from a wrecker. that keeps things tidy. a google search would likely turn up some pics.
https://www.tascaparts.com/oem-parts...cable-23239733

[TX3100Guy]

Originally Posted by dsraven

I assume you will be running the pos cable to the starter and from there you will draw power for the circuits, correct? the same way chevy did it for years except you will use a pigtail cable from the starter over to your mega fuse pack instead of fusible links in the wiring connected to the starter terminal. if thats the case then you will want to mount the mega fuse as close to the starter as possible for the shortest unfused wire from the supply to the mega fuse.
another way to achieve the same result is to draw power for the mega fuse directly from the battery. the later model chevy trucks (mine is a 2015 and I just replaced the battery in early Jan so thats what sparked the thought) come with a battery cable terminal that has an extra lug on the side and that connects to a mega fuse holder connected right at the battery. you could draw power right from the battery that way. possibly an aftermarket supplier could come up with the correct style terminal or cable for your application needs since the GM cable is a little spendy. just a thought. or maybe you could come up with a good used cable and the plastic holder that fits the mega fuse thing from a wrecker. that keeps things tidy. a google search would likely turn up some pics.
https://www.tascaparts.com/oem-parts...cable-23239733

I actually did what you suggested. I mounted the Mega-Fuse blocks on the frame adjacent to the starter. My red (positive) battery cable goes direct to the starter and with the 6 gauge wire supplied by American Autowire, I made a i foot long jumper to go from the started to the Mega-Fuse block. From there a smaller gauge red wire goes to the ignition circuit and the rest of the supplied 6 gauge wire goes directly to the one wire alternator that I purchased. A purple wire from the ignition circuit goes to the other solenoid terminal on the new high torque starter. Now to find a path for the other 40 or so wires....

[dsraven]

how many mega fuses are you running?
if you think back to the old cars that connected all the power at the starter you might remember there were a couple of fusible links in the wires close to the starter. newer cars use the mega fuses, several of the really big plug in fuses with the tangs, plug in fuseable links, etc. if you look inside the relay/fuse center under the hood of a newer chevy you may see all of those being used. personally, I would run power from the mega fuse to the fuse panel and from there to the rest of the circuits. sorta like a house breaker panel. power comes into the house, through a main breaker (your mega fuse) then to the individual circuit breakers and THEN out to the load circuits. that way each circuit has a fuse. a mega fuse of appropriate amperage should be placed inline from the alternator to the battery as well. it protects the alternator from an excessive overload in the truck and it protects the battery and thruck circuits from an alternator problem
anyway, not sure how your wiring will be set up but, you will wanna make sure all your circuits are protected by a fuse rated for the load on that particular circuit.
what amp rating is your mega fuse?

[TX3100Guy]

Originally Posted by dsraven

how many mega fuses are you running?
if you think back to the old cars that connected all the power at the starter you might remember there were a couple of fusible links in the wires close to the starter. newer cars use the mega fuses, several of the really big plug in fuses with the tangs, plug in fuseable links, etc. if you look inside the relay/fuse center under the hood of a newer chevy you may see all of those being used. personally, I would run power from the mega fuse to the fuse panel and from there to the rest of the circuits. sorta like a house breaker panel. power comes into the house, through a main breaker (your mega fuse) then to the individual circuit breakers and THEN out to the load circuits. that way each circuit has a fuse. a mega fuse of appropriate amperage should be placed inline from the alternator to the battery as well. it protects the alternator from an excessive overload in the truck and it protects the battery and thruck circuits from an alternator problem
anyway, not sure how your wiring will be set up but, you will wanna make sure all your circuits are protected by a fuse rated for the load on that particular circuit.
what amp rating is your mega fuse?

The kit from American Autowire comes with two 175 amp fuses. The fuses are side by side, with a heavy gauge plate connected between two of the fuse ends on one side. The 6 gauge wire from the starter gets attached to the side of the fuse block that has been jumpered between. Another 6 gauge wire is installed onto the other side of the fuse block on one of the fuses and then directly to the alternator. Finally, a 10 gauge wire is fitted on the other of the two fuse terminals and that wires goes directly to the fuse panel in the truck.

[dsraven]

looks good, the red 6 ga wire that goes to the main fuse panel, as the supply for the panel, is fused at 175 amps. thas a lot but at least it is fused.
keep in mind that there is a larger size wire needed for a longer run of wire in order to be able to still draw the same amperage. here is a chart that will show you what ga will be required for loads over different lengths. it's always good to figure out what the current draw will be for accesories on the same fuse so that you don't overheat a connection (where resistance becomes heat) or fuse holder (again, heat). I am sure the harness has been built with certain accy circuits labelled for that reason. I have included a link for a chart that is easy to figure out if you plan to modify the plan as to what wire does what or add in an accy that isn't in the wiring diagram.
https://www.crutchfield.com/S-0AbhTP...uge_chart.html

[dsraven]

I was also going to mention that installing the mega fuse on the truck frame is fine and all, but installing it on the body is sometimes better because it allows the body to be seperated from the frame without too much hassle. that was one reason for suggesting to mount the mega fuse by the battery but if the battery is not easily accessed then that is also a pain. if you don't plan to take the truck apart then it doesn't matter. a lot of guys do a full mock up, drill holes where they need to be, install nut serts etxc etc. then the vehicle is taken apart and all the parts get bagged and tagged untill after paint. then it goes together again for the final time.

[dsraven]

it sounds like the new harness is pretty easy to follow along for what wire goes where. bonus. I have seen some guys sell the project because the wiring got started and got too deep for the owner. once wiring is started a lot of shops won't want to take over and continue with that particular harness because they have to warranty their work on stuff they don't have history with.
after having wired a lot of things from scratch I can say you may want to invest in some of those velcro release cable ties. it helps to bundle a harness together so you can easily add a new wire to the bundle without undoing tape or doing an estimated length but then finding out you were too long or short. when done they can be removed after taping the harness in a few spots (or fully) and then running the wires in a loom of some sort before clamping them down to something. if using the plastic split loom there are tools made to help you get the wires inside the split loom as well.
here is a link so you can see what the tool looks like and how it works
https://www.cablesnmore.com/split-lo...tallation-tool
https://nickstruckparts.com/products...plit-loom-tool
there are also different options for loom you may not be aware of as well as clamp styles, tools, fuses, relays, pigtails, connectors, tech articles, etc, etc, which this link shows. check their home page for a drop down
https://www.wiringdepot.com/store/c/...Wire-Loom.aspx
there are also lots of split loom fittings available to make your life easier and help you make a proffessional looking job
https://www.wireloomtubing.com/plastic-conduit

[dsraven]

forgot to add this link for fasteners for split loom
https://srfast.com/type-2/wire-loom-clips-straps/

hope all that helped somebody, haha.
keep posting up pics as you go. its great to see others work get done when my own is not closeby.

[TX3100Guy]

Originally Posted by dsraven

forgot to add this link for fasteners for split loom
https://srfast.com/type-2/wire-loom-clips-straps/

hope all that helped somebody, haha.
keep posting up pics as you go. its great to see others work get done when my own is not closeby.

Wow! That is a whole bunch of terrific information. The tool to insert wires into split loom looks like a winner for me. I bought a Painless Wiring kit of various sized split looms and have found it "fun" to insert just two wires into a small loom. That tool look like the next thing for me to order. Many thanks!

[Rickysnickers]

Dennis, I can only imagine what your bookmark menu looks like, LOL

[dsraven]

haha, thanks for noticing snickers.
hopefully the info makes for an easier job and a nicer looking finish. some of the tech articles are good to read or watch as well. good info.