8.1L and 4L85e swap into a 1972 Custom Camper 4WD

[edgooch]

I hit a couple of snags. I managed to get the truck running and was able to see the potential it has. However it was plagued with electrical problems. I have almost no experience in automotive wiring, but for some reason decided to rewire the chassis and dash at the same time that I installed a complete new aftermarket A/C system AND converted the truck to a modern computer controlled vehicle. The four systems weren't designed to go together so I had to figure out how to mate then. That task proved to be over my head. My son, who lives in Alaska, is a wiring wizard, with years of experience. I also had a vacuum leak in the engine that i couldn't diagnose until the electrical problems were resolved. So, my son now has the truck in Alaska. He plans to have it running next spring. I am not sure if he will participate in this forum.

[SS Tim]

Originally Posted by edgooch

... So, my son now has the truck in Alaska. He plans to have it running next spring. I am not sure if he will participate in this forum.

Any good news?
Is your son a forum member?
Do you have any more pictures you can post?

[Spalding]

Hi Tim,

So, as Dad mentioned above, I had the truck shipped to Alaska last spring. I got the truck tucked into the garage and then my wife and spent the summer camping and riding UTV's like we usually do. When fall arrived I dug into the truck and got started. Been making pretty good progress as of late, but still a ways to go. Suffice to say the engine is back out and the front clip removed so I could notch the frame for the OEM exhaust manifolds I want too run.

I don't usually participate in forums, but this seemed like a cool opportunity to continue the build thread so I figured I'd give this a shot. Once I figure out how to post pictures I'll get started with updating the progress.

[SS Tim]

Welcome to the forum!
Posting pictures isn't difficult for the most part.
Start with the "Go Advanced" button and use the paper clip link or the attachments button to upload pictures. Keep them small and please avoid linking to an off site host, all too often this results in broken links and missing pictures down the road.

[Spalding]

Tim, thanks for the tips.

Here's a photo of the truck when I picked it up at the Anchorage dock in early spring. Dad did a nice job packing the bed full of parts I might need.

[RRR18]

Following.

[Spalding]

Here about a couple months ago I started by surveying the truck and making a list of things that needed to be done. As I started stripping the front clip I started looking for any problems areas that I wanted to focus on. I knew the exhaust manifolds were going to be the toughest problem to deal with and I wanted plenty of room to work on that issue. I don't have a lot of welding experience so the more room I could make for myself the better my chances at quality.

[Spalding]

I decided to start with the hardest item, replacing the exhaust manifolds. Dad had installed 454 manifolds because they fit within the existing frame rails, and I've read this is commonly done with 8.1's in tight spaces. However, the driver side exits in bad spot, and the OEM manifolds are just plain bigger and would appear to flow better. Dad had shipped me the OEM manifolds with the truck so I fitted them on the block so I could see where the cuts would be required.

I paused before going forward with the cuts. I was a bit nervous about cutting the frame and I didn't have torch. After reading and researching other builds where this was done, talking to a few people that have fab experience and shopping for a plasma cutter I was finally ready. After making the cuts I could start figuring out how I was going to box in the frame at the area of the cut.

[Spalding]

After I cleaned up the reliefs I made some cardboard templates of the pieces I was going to use to box the area of the cuts. I cut the pieces out of some 3/16 steel plate (same thickness as frame) and then welded them in place. My welding skills are not great but I got better and better as things went along.

[Spalding]

At this point I decided to set the engine back in and see how well things fit. I learned my driver side was a bit too tight. Everything fit, but I could tell removing the down pipe at the manifold collector would be tough it I ever had to take things apart. I figured now was the time to make it right so cut part of my box back out and lengthened the relief a bit on that side.


Finally I ground all of the welds and generally smoothed things out a bit. Then some paint and undercoating.

[sdwolff98]

Looking good Spalding nice welding work Waiting on my body guy to get finished so I can get my 8.1 beast up n running soon.

Sean

[MMcMasters]

Very cool!! A few years back I had a 2wd 2002 Dually with an 8.1/ Allison and that thing was a horse. That should be a fun truck!

[Spalding]

Thanks guys. I'm pretty happy with the way those reliefs turned out. We'll see if the exhausts fit like I think they should when I get the motor back in.

Before wrapping up the frame work I welded up a few holes in the frame and crossmember that had been added but I will not use during my reassembly, and I installed a steering box brace to help reduce frame racking while turning (previously I noticed the front crossmember was starting to come loose where it is riveted to the frame rails and the steering box mounts were all loose too). I bought the frame brace from ORD and it fit well with only a minor amount of modification where the brake lines pass between it and the frame. That plasma torch has made things like that really easy. I also checked to make sure the harmonic balancer was going to clear the new brace the last time I set the engine in place to verify exhaust reliefs.

Since my fab work on the frame appears to be done I masked off some areas that needed paint from firewall forward, including the frame.

[72 tigger]

Nice work! Glad you can help your dad out!

[Spalding]

It's been a while since I updated this post. Been making steady progress over the last several weeks and the list of to do's will keep my occupied for the rest of the winter I suspect.

I decided to give the engine block a new coat of paint and while prepping it I noticed some things that I needed to investigate. I remembered Dad had noted that after he had the intake manifold powdercoated there was an abundance of blasting media inside the manifold that was tough to get out. I noticed more of it in the intake plenum after I removed the throttle body and decided to remove the intake to look further into it. I found signs of media in almost all intake runners and when I removed the rear vacuum port plug on the intake I found gobs of media/sand.


I know Dad had spent hours flushing that intake when he got it home so I wasn't confident that more flushing would ever get all of it out. I also knew that Dad had only run this engine for about 20 minutes so I figured there shouldn't be much damage internally but I decided to pop the oil pan off and look at the rear main bearing (closest to oil pump) for damage. Thankfully it looked perfect.

At this point I mapped out a scope of work for the engine and ordered up a rear main seal, pan and intake gaskets (updated GM intake gasket 89017539), injector o-rings and I also called a friend of mine who has a few 8.1's and he gave me one of his intakes. I also ordered a new A/C pump bracket the locates A/C pump to top of driver side but still has provisions for std power steering pump, not the larger Kodiak chassis pump (I noticed this bracket while looking at the 8.1 in my Winnebago).

I cleaned up the block and parts and put a new coat of paint on block, pan and intake and then assembled.

[Spalding]

I set the engine back in the chassis to see how things fit and it looked pretty good. I couldn't wait to see if the Hydroboost mount bracket I found on Ebay, the P/S pump I ordered from Rock Auto and the hydroboost hoses I ordered from the local GM dealer were all going to play nice so I mocked it up with success.

The newer o-ring style power steering hoses from the pump wont fit into the older steering gear box but I read somewhere that I could swap out the gear box with a 86 K20 which will accept the newer lines. It will also tighten the steering from 4.5 turns lock to lock to 3.5 turns. I picked up the new gearbox the other day and will post install pics soon. Suffice to say it all fit great, only added piece I needed was a new rag joint for the new gearbox since it used a smaller input shaft diameter.

[Spalding]

The original core support was rusted through in a couple of spots near the battery tray so I ordered a new one a couple months ago. Now that the engine is back in I got the chance to mock it up with the radiator and electric fans that Dad had purchased. Found a few conflicts and I made some mounts to adapt the shroud to the radiator. I also had to drill out the spot welded lower radiator saddles and recycle them to the new core support. Looks like the new core support was set up for a 3 core radiator where this truck has a 4 core.

I made some reliefs on the lower corners of the shroud where the bottom radiator saddles where hitting it and changed location of the fan circuits so they existed the shroud closer to where I plan to mount the relays.


Radiator and fans painted and installed. Now I'm into wiring.

[Spalding]

Speaking of wiring, here's a tip that might be useful to some members. If space permits, sometimes it makes life easier to joint the two wires you are soldering with a piece of wire wrapped around the overlap, like this:


Then solder:


Then heat shrink:

[Spalding]

Made good progress on wiring this week. Still much more to go inside the truck but the driver side engine bay is taking shape:

[SS Tim]

Great progress! Thanks for taking the time to post and just as importantly photo documenting the hurdles as you overcome them.

[Jason7121]

Great idea on holding the wires together I'll have to use that trick!

[Campbel45]

Any more updates?

[edgooch]

A lot has happened since our last post on this truck project. The good news is that the 72 K20 Custom Camper is done. The 2004 8.1L was completely rebuilt and a mid-range Competition Cam installed. I had it dyno-ed in Seattle. 450HP at the rear wheels and over 600 ft/lbs.

Just a quick review. I started the swap in 2014 after acquiring the engine, transmission, ECU and a variety of other parts from a 2004 Suburban. I determined the basic architecture of the new setup - mounts, crossmembers, firewall mods, etc. However, I quickly figured out that I was over my head when I tackled the wiring (New harnesses throughout, new Vintage Air A/C, moved gas tank.) So I shipped it to my son. He is a detail wizard. Thanks to him, the finished product looks, runs and drives like GM did it. In particular, the steering box made a huge difference. It has won a couple of trophies in the Seattle area and now resides here in Wasilla, Alaska where it is lurking in my garage, waiting for clean dry streets.

[Spalding]

Campbel - I'm glad you asked about progress. I've been meaning to update the project thread for a long time, but work just keeps getting in the way it seems. Like Dad said, the cool part is that's its finished and being enjoyed. Makes me pretty happy to see Dad take it to shows and generally having a good time in it. Engine runs real strong and the 8.1 quickly identified a need for a posi in the rear axle (an HO52 no-spin or an axle swap might be in the truck's future). Doesn't take much to light up those tires and driving it around the engine makes it feel like the truck weighs about as much as a Volkswagen.

Here are some more photos of the project in final stages.

[notsolo]

Wow, beautiful truck nice complete build. Good things take time, well worth the wait.