'72 GMC K25 build 454/4L80e

[FRENCHBLUE72]

Awesome looking truck it came out very well... Whats the total build time?

[superchevy]

Thanks guys. It's been 4 years of off-and-on work. I haven't done much since this past Spring because it's just been too damn hot. I did get out there yesterday and today to install a new tierod centerlink...the old one had a slight bend in it and was causing some alignment issues...MUCH better now, and today I installed some 6 degree axle shims in the rear to correct a slight pinion angle vibration...again, much better now.
I snapped a couple of pics of her sitting there in all her dusty glory.
With the alignment and pinion angle issues corrected, I can now take it out on a long shakedown cruise...hopefully at least a 100 miles or so. As it is, I've only put 31 miles on her so far in some shorter runs around the neighborhood.
Sorry about the pics...it's hard to photograph in the dark barn.
Just a couple very minor things to do now.
Casey

[superchevy]

Well I finally got a chance to take the K25 out for a long drive. I washed the thick layer of dust off...her first bath by the way...and took her for a nice 35 mile run through the back country roads to Wimberley and back to the shop. Wow. What a difference in steering and handling that new steering link and alignment made...very nice. She rides so smooth, and loves 70-75 mph on the freeway thanks to the 4L80 overdrive.
You might also notice I put on a new set of black step bars. I didn't like the small aliminum steps that I had installed...they looked to dainty for such a big truck.
She still hasn't gone a 100 miles yet, lol.
Here's some pics.

[superchevy]

more

[mjensen]

I love the look of that truck!

Great job!

[71sierragrande]

Unbelievable!!!!!!

[Mr Chevorlet]

I can only say one thing. BEAUTIFUL BUILD and TRUCK

[CHEVY072481]

what stand alone computer harness do you use fo the 4L80E/np205?
I would like to use that setup on my truck.

[superchevy]

Well, the last test drive revealed that the rear end gears were shot...the high-pitched whine was a dead give away, so after some more testing and confirmation, it was time to install some new 4.10's and a new TracLoc posi unit. I am lucky enough to have a good friend who sets-up rearends all the time, so I bought the parts and he did the install.
There's not any pics of the set-up as I was out of town during the install and my buddy didn't take any snaps. He left the rear open to show me the test pattern on the gears and backlash, so I do have a couple of pics with the case spreader installed.
Here ya go: First pics are of axles pulled, draining the rear end gear oil, the case spreader installed, the new 4.10 gear set and TracLoc posi installed, and the rear end cover reinstalled.

[72LSK10]

Sweet looking K25, I love the way these trucks look in black.

[allchevy58]

You did a nice job, looks great!

[superchevy]

Well, while the new rear posi/gears were being installed, I decided to install a FAST EZ-EFI fuel injection and replace the first-gen TCI trans controller with their new EZ-TCU controller and harness.
That's right, I pulled off a perfectly good running Sean Murphy built/tuned quadrajet with only 80 miles on it to try out a fuel injection set-up I scored from a friend of mine who sold the project he was going to use it on... I MUST BE CRAZY!
So follow along while I do the install.

Here's a shot of the carb before removal. Because the FAST tb uses a Holley square flange, I had to install a 1" adapter to the Edelbrock quadrajet intake. A couple of shots of the FAST tb sitting on the intake...looking good!

[superchevy]

FAST recommends using an aftermarket ignition for a hot spark and most importantly to pull a clean rpm signal from. I have a custom-curved DUI HEI already installed, so I bought an MSD 6A and wired it in. Because I am really trying to keep the engine bay fairly stock looking...like a '70 Chevelle SS lets say...I wanted to try and hide the big red MSD box. The only spot I could find that I liked was on the driver's side of the core support, so that's where I put it.

[superchevy]

Now for the fuel system. I bought the FAST 600hp fuel pump kit. I needed to put a bung in the rear mounted suburban tank. I dropped the tank, drained the fuel, rinsed it out with water about 5 times, then let it air dry for a couple of days. I marked where the bung needed to go, then filled the tank with water again and drilled a hole for the fuel line bung. After installing the bung, I attached a small piece of fuel line, blocked that, and filled the tank to check for leaks...no leaks. I then painted the top of the tank with a black satin finish to match the frame...I didn't paint the bottom yet, because I knew I would scratch it putting the tank back in, and I'll just paint the bottom half after it is installed.

[superchevy]

It was time to mount the FAST electric fuel pump. FAST recommends to mount the fuel pump as close to the tank as possible and as low as possible. I decided on a spot on the passenger's side frame rail right before the kick-up over the axle.

[superchevy]

I ran the fuel line from the pump up the frame rail to the engine compartment and then up to the throttle body. For a return line, I used the fuel line I had already run as the carb's inlet line...the fuel will return to the tank through the stock pick up on the top of the tank.
I had to remove the mechanical fuel pump, which made a great place to mount the FAST fuel pressure regulator and gauge. If you look close at the pic, down near the A/C compressor bracket, you can see the regualtor and gauge. Again, I'm going for as stock appearing as I can, and I fabbed up a custom bracket to locate the regualtor and gauge in a bit of a hidden spot.

[superchevy]

It was time to break out the wiring harness and start wiring this badboy.
I welded the O2 sensor bung in the driver's side exhaust pipe about 25" from the rear of the cylinder head...FAST recommends no closer than 21". After screwing the O2 sensor and routing the wiring connector, it was time to try and hide the mounting of the FAST ecu. The relative shortness of the wiring harness and the need to reach the battery, O2 sensor, and other wiring concerns, led me to choose a spot on the driver's side firewall behing the hood hinge mount. This spot is relatively hidden, and since the ECU itself is black it sort of blends into the backgtound...sort of. After mounting the ECU, i was able to attach all the sensor connections.

[superchevy]

Because the EZ-TCU shares a tach signal and tps signal with the EZ-EFI system, to facilitate wiring them up together, I needed to remove the old TCI transmission control unit and wiring harness. I have the tcu mounted in the stock center console, and the harness routed through a hole in the floor. I removed the old tcu, then the console, and then pushed the old harness through the hole and disconnected it from the 4L80e tranny. Here's a couple of pics of the old tcu and old harness connected to the tranny.

Because I am such a stickler on hiding wiring and trying to make everything appear as factory as possible, these pics are over several weekends of work. My buddies are calling it SLOW EZ-EFI because I'm taking so long to get it finished, LOL.
Anyway, 98% of the wiring is finished, and I just have a few loose ends to wire up in the cab...mostly the new TCU, and then it will be time to fire it up.
Hopefully in the next couple of days with a little effort after I get home from work. I will keep ya posted.

[mjensen]

Love it! Looking great!

[kamikazekyle05]

Great build. How do you like the the ez efi? Im really contemplating getting one

[superchevy]

I haven't got the efi fully installed yet, so I don't know how I like it. I do know it is a lot of wiring, lol, and I hate wiring.
Here's a couple of pics of the new air cleaner I am going to use. For those of you following the build, I had originally been using a '72 Corvette dual snorkle cleaner. With the 1" carb adapter plate installed and the relative flatness of the Corvette cleaner base, I didn't like how much of the throttle body and injectors I could see. So, I bought a GM restoration '67 big-block Chevelle air cleaner that has a deep dropped-base that hides most of the throttle body, injectors and sensors. I think it looks great.
Here's a couple of pics of the new air cleaner, as well as a few pics of the new TCI tcu harness being installed and run down through the hole below the console.
Fist pic is looking forward drivers side frame rail...you can make out the O2 sensor way down the exhaust pipe. The second pic is looking forward down the pass side.
Still have a few wires to connect, then I can power it up.

[superchevy]

Well, a little more progress on the EFI and TCU install today. I got the wiring finished up under the dash...you can see the extra fuseblock I installed a while back for all the accessories I have installed on the truck. That extra fuseblock is an NOS 64 Chevy truck accessory block I got on ebay... it matches the factory block pretty well.
You can see the computer cable from the EZ-EFI computer on the firewall routed through the steering column grommet...this is the cable you attach to the EFI hand-held unit to manipulate the EFI settings.
I also got the new EZ-TCU controller and hand-held mounted in the factory console.
Only a couple of loose ends to finish up now...hopefully by Christmas day.

[67HEAVEN]

Very nice build. You shoul be proud of your vision and of the results.

[superchevy]

Thanks 67HEAVEN.
I read through your '67 Vette build and I'm still drooling! That car is gorgeous!

[turp mcspray]

Nice looking truck! Any updates? What did you use for a cam?