FiTech Install on 72 C20 w/ 402 and TH400

[sophistical]

Background:
I've had my 72 C20 for about 15 years and I haven't been driving it much (sadly) in the last several years. However, recently my daily driver (newer BMW Sedan) was destroyed in a flash flood in a parking lot. I hadn't planned to buy another vehicle for a couple years at least so decided I'd make the 72 my daily driver.

The carb was a mess anyway (from sitting) so I decided if I was going to make it reliable I might as well do EFI. This forum has been helpful so I wanted to share my experience.

What I had:
72 C20 with Holley Street Avenger on 402 w/ TH400 Trans and later model Chevy HEI and an Air Gap intake.

Parts I had to purchase:

• 1/4" brass tee (for fuel return)
• 1/4" and 3/8" fuel hose
• new 1/4" and 3/8" clamps
• some 3/16" x 1-1/2" strap steel to fabricate command center mounting
• Jegs Part 55-15269 1/2" to 1/4" ball carburetor linkage bushing
• Flat bottom 14" air filter base
• 5/16" to 1/4" air filter stud adapter

Fuel Return:
I hadn't figured out how I would do the return before I got the unit and this was my biggest concern starting the project. To my surprise the 72 system has a 1/4" return line. I called FiTech to see if it would be ok to tap into that and they said sure. I just Tee'd into it where the rubber line goes between the factory fuel pump and the hard line.


Command Center Installation:
I decided to install the Command Center behind the passenger side headlight between the battery and the fender. Note, this may not be ideal as the Command Center can collect water from rain or washing the car when placed here; plus it's a tight fit for connecting wires and hoses during the install. However, it's on the same side of the vehicle as the fuel lines so routing is simple and easy. I routed the vent/return line and input up from the passenger frame rail under the battery box to the Command Center. I used existing bolts and holes to fabricate a mount for the Command Center in this location (see pictures).





Fuel Supply:
I routed the fuel supply from the mechanical pump up through a filter into the Command Center, then from the Command Center under the battery and up over the back of the A/C pump into the front of the throttle body.


These images are with the battery box removed.


Wiring:
I soldered the tach wire into the existing wire coming from the tach. I ran the ignition wire into the cab and connected to a wire that was hot when the ignition is on. I routed the pump and power wires through the fender to the Command Center location which is right next to the batter (for constant power).



Throttle Connection:
I just moved my 1/4" ball to the FItech linkage and it started and ran but didn't have full throttle. I have ordered Jegs Part 55-15269 1/2" to 1/4" ball carburetor linkage bushing which should give me a longer throw to increase leverage. The throttle is very stiff in the current location.


Control Unit:
I ran this through a grommet into the cab and suctioned it below the dash; works great.


Everything Else:
Everything else (coolant sensor, vacuum lines etc.) was all so self explanatory I didn't include details here. I did not use the fan control or ignition control.

Issues:
I only had two issues, neither related to FiTech. First, the ignition wire I tried to use was the one that had been run to the choke. It turns out it wasn't hot when cranking (the handheld unit showed 0 rpms). A quick call to FiTech figured this out. I also had issues with my factory fuel pump failing during this process but once I replaced that all worked as planned. I did have to order a different base for my air filter as mine had too much drop but that wasn't a real issue.

Performance:
Once I had primed the system, entered 402 for the engine size (it reset to 401 for some reason), set the cam to 1 (stock) I cranked it for a bit and it started right up. I've been driving it ever since with no serious issues. The only thing I need to tweak is that when I take my foot off the gas and brake around a tight corner, when I get back on the gas there is a small stumble. That's exasperated by the stiff throttle cable. If it's still a problem when I replace the throttle linkage I'll dig into the tuning but it's so minor it's not a concern. I had a business trip this week and drove the truck to the airport. When I got in to go home at 11:15PM it was 38 degrees; the truck started with just a single turn of the key. That was rewarding!

All in all I highly recommend this product! I have no fuel smell in the cab or anything like that to deal with. I think my stock tank (non-ECC btw) vents out around the cap, it works well, and makes your engine start and run like something much newer.