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The Shop Truck

1971 Chevy C20 with a custom flat bed.
Overview Gallery Discussion
I put the truck on the lift so I could work on the toolbox power distribution. I pulled out the old relay box and got the new one mounted. I made a wire bundle to just wire 7 of the 8 relays to the ECU so adding circuits in the future is easier. I'm not a fan of the differences between the 4 circuit and 8 circuit relay boxes from Leash. On the 4 circuit it has a built in fuse for any negative trigger relays and you can make any relay negative or positive trigger. On the 8 circuit I have to order it specifically with negative trigger relays that can't be switched and I have to run a wire over to power them. This was the cleanest way I could think to do it, but I don't love it.
IMG_20260310_174532640.jpg

I should be able to finish up all those circuits today and get back in the cab doing wiring. Part of the reason I'm redoing so much of this is because I had been using this (what I thought was nice) silicone sheathed electrically tinned copper wire. What I've discovered is that the sheathing breaks very easily so I'm ripping it all out and replacing with either Tefzel for important circuits or PVC for the less important ones. It's a pain in the a$$, but necessary.
 
r3dd0g said:
I put in a Detroit Truetrac torsional limited slip diff. It's awesome.

Zoom in on the alternator. It's the 370 amp Mechman. After I lost a fairly new Power Master on the dyno, I switched to Mechman.
IMG_20260309_140318245.jpg
Click to expand...
I'd get the numbers off it and actually call Mechman.
Their high amp (higher than 300) won't take RPM.
I called them when I got mine and was told I had to go to their 250 for anything that regularly seen more than 5k.
The high amp ones are geared towards stereo guys that idle for long periods and drive around rarely hitting high rpm.
When I asked the tech dude about changing the drive pulley to slow the alt down he treated me like I was a 3 year old moron.
I went with the 250.
I'd call them and verify you'll be ok before you fry that one. Maybe they'll trade it back for THEIR 250. :dunno:
I was told I'd be fine with it going to 7k a bunch.
 
shady said:
I'd get the numbers off it and actually call Mechman.
Their high amp (higher than 300) won't take RPM.
I called them when I got mine and was told I had to go to their 250 for anything that regularly seen more than 5k.
The high amp ones are geared towards stereo guys that idle for long periods and drive around rarely hitting high rpm.
When I asked the tech dude about changing the drive pulley to slow the alt down he treated me like I was a 3 year old moron.
I went with the 250.
I'd call them and verify you'll be ok before you fry that one. Maybe they'll trade it back for THEIR 250. :dunno:
I was told I'd be fine with it going to 7k a bunch.
Click to expand...
Now that you mention it, I remember that from when I bought the other Mechman I have. When I ordered, they just asked if I wanted to upgrade to a Mechman, I didn't realize it was going to be the 370Amp one.
The Wegner drive kit uses a smaller crank pulley than stock, so you actually end up putting a smaller pulley on the alternator. I could set the 370 aside as a spare with the stock pulley to underdrive it and put my 250Amp one back on.
 
On their site it had the option of 250 power Master, or 370 mechman. I remembered you saying Mechman, so figured I'd mention it lol
 
I missed the amperage ratings on that, I just saw "Mechman upgrade" and went with it.
 
It doesn't look like much progress even though I spent the entire day out in the shop, but here's the picture.
IMG_20260311_110636520.jpg

I re-ran all the wires for the triggers and loads coming out of the rear PDU, it took a lot of time, but it looks better and it has better wires.
I'm down to three pass through areas that I need to finish cleaning up and replacing wires.
-The back of the cab has a pass through that is 90% finalized, I'm going to move the wiring for the flex fuel sensor here when I re-wire it, then I can install the grommet and call that done.
-The transmission tunnel has the transmission wiring, one O2 sensors wiring, and the flex fuel sensor wiring going through it. I'm going to reroute the O2 sensor through the firewall and the flex fuel through the back to finalize that one.
-The final one is the firewall pass through where all of the engine wiring will go through. This is the part that needs the most work, I have all of the wiring loom and electrical tape removed from the Holley harness as I am making a ton of changes. I'm really dreading this part as it's very uncomfortable working in the cab with the seats out. I also don't have everything I need to wire up installed yet, so I have to try to think ahead.

I got the o-rings from Whipple and the fuel injector adapters from Amazon today so maybe I'll play with that stuff tomorrow to take a bit of a break from wiring.
 
I was sitting at dinner last night and I remembered that I didn't run the wire for the intercooler pump, good thing I already set up the other 4 relays to run to the ECU for the signal wire. Now I just need to pull the harness going back to the fuel tank and add another 12ga wire to run the pump.
Babaganoosh said:
What pass through you running? I need to do some, I welded all the holes closed in the cab.
Click to expand...
I'm using this style in the toolbox, the trans tunnel and on either side of the firewall by the fenders:

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I like that you can cut off as much as needed to fit your wire bundle, but it won't work with the main engine harness as it's too large.
For the engine harness I got one of these:
The main harness will go through the bigger hole and I'll use the smaller one for the EGT thermocouple wires.
At the rear of the cab I'm going to use this one:

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This one is nice and rounded on both sides, which is good because wires go both directions once it goes out of the cab.
 
I love the end result is always cool. But getting started is like pulling teeth for me lol.
Love the way that relay panel ended up
 
I will say that it was very easy to add another circuit to the relay panel. It only took me about 30 minutes to pull all the fuel pump wiring back and add the wire for the intercooler pump.
IMG_20260312_093003671.jpg

The only wiring going through the transmission tunnel is for the transmission now, O2 has been rerouted out the firewall with the other one and the flex fuel is going out the back of the cab, but I still need to finish that wiring.
 
I took a break from wiring today and worked on plumbing. I made up new power steering lines and routed them much cleaner than before.
IMG_20260313_145630613.jpg

IMG_20260313_145622958.jpg

IMG_20260313_145613565.jpg

I'm happy with how they came out and it gives more clearance for changing plugs.
The next problem is the supercharger intake. I realized today that they only gave me the o-ring that was pinched, they didn't send me the one that was missing (it was a kit with multiple o-rings, I just assumed it had both). The other problem is the fuel rail. For some reason they designed it to use LS3 style injectors, which are super short. I already have 2 sets of LS1 style and don't feel like spending $1600 on another set of injectors.
IMG_20260313_171623638.jpg

It's kind of hard to see with the black on black, but you can see how far the mounting brackets are from the manifold. The LS3 injectors are over an inch shorter, but I have the brackets on the lower hole which I believe are for truck injectors. the brackets are just steel so I'm going to cut them up and modify them to work. I don't know why they don't just make a few different brackets.
 
This is a universal "hot rod" kit, not a bolt on kit. While they do make application specific bolt on kits (newer Camaros, Silverados, Mustang's etc), they don't make a specific kit for an LS with rectangle ports installed into a '71 C20, not surprisingly.
After doing a little research I believe the reason is that using that intake with one of their low profile inverted blowers requires the use of the super short injectors. I'll just make new brackets.
 
Set the upper on before you make brackets.
They may have to be short for clearance :dunno:
Couple of the SC pics I seen the actual head went over the injector rails.
 
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