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

After thinking it about for 8 years, the swap has begun. My '72 looks good, but it has the original engine in it. The odometer shows 02,XXX miles. I don 't know how many times it has rolled over, but that old 350 is tired. The 8.1 and 4L85 are out of a 2003 3/4T Suburban. The engine has 80,000 miles on it and the tranny has 10,000 miles on i.

I have checked the engine carefully and while doing so, installed a new mid range Comp Cam and lifters. The ECU is off at Howell Engine Development to be reprogrammed.

After assembling parts, the first step was to move the gas tank out of the cab and put it behind the rear axel. I pulled the bed off using an engine hoist and a 4x4 timber "H". Two bags of fertilizer provided the needed balance weight.

The tank is for a 72 suburban. After removing the spare tire brace, it fits right in. The third brace from the back under the bed has to be cut down (up?) to fit over the tank.

More Pictures tomorrow.

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

Lifting the bed off was a one person operation, with the use of an engine hoist and 4x4 frame.

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

This is my plan too, but I was figuring on 2x4 instead of 4x4. Now I'm second guessing that. Short/wide box, wood bed.

I'm looking forward to the progress on this thing. That 8.1L is huge!

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

The fuel tank (from LMC Truck) is installed, ready for plumbing. Couldn't have done it without the excellent help of my grandson, Zach. A significant modification is the addition of an electric, in-tank fuel pump. It is an Airtex 3501M and is the specified replacement pump for the engine/tranny donor vehicle. It is spring loaded, so it fits perfectly (height wise) in the LMC tank.

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

I would worry about the 2x4 twisting or bending.

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

The bed brace has now been cut to accommodate the tank. I marked the cut line with a Sharpie then cut it out with a cutoff wheel on an angle grinder. Then I welded the bottom of the brace back on. Note the 2" hole in the brace to the right of the bed bolt. The hole is angled up and to the right. It is lined with 2" tubing and both ends are welded all the way around. The filler neck hose will go thru the hole and up to a new door in the side of the bed just behind the left rear wheel well.

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

I'm gonna watch this one

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

Just a thought but, -- DONT ruin your bed by cutting a hole in it for the filler neck -- put it behind the marker light. I put mine in a stepside and it was super easy, a fleet side will be a little tougher because its a little tighter but definitely doable. Search "gas filler marker light" - there are several threads on here.

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

Tommys72,
I am looking for input and ideas as well. I have never done a project like this before. Thanks for you service.

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

I am working on "the right solution" for the filler door. I saw this truck at the Good Guys show in Tacoma recently and loved it. It sort of makes you say, "did that come that way?". I have delayed that decision while I look at alternatives. Thanks for the ideas!

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

Personally I don't think it's "ruining" the bed because there is nothing done by adding the fuel door that can't be undone at any time by a good fabricator.
I agree though that on a 68-72 truck the marker light approach is a good one.

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

I have made some progress since my last post. The gas tank is installed, including fuel lines and fuel pump wiring. I may have to move the wiring around when I put the bed back on, but that will be easy.

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

While I was working around the back of the frame, I installed some new Monroe Gas Magnums.

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

I have also been busy at the front of the truck. The bumper, grille, hood, fenders, radiator and radiator support have all been removed. The old engine is ready to come out.

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

I have decided to solve the new engine crossmember problem by purchasing the DIY4X crossmember kit. A link to the product is below. The picture on their website is old. The kit one includes a removable center section. That section is the only thing that will have to be modified to fit the 8.1 oil pan. Here is a picture of one done for a 72 Blazer. You can see that build on the CK5 forum. Look for Igor.

http://diy4x.com/cart/index.php?rout...&product_id=80

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

As I took the front clip off of the truck, space quickly became an issue. I had no where to store the big body parts. I was also concerned that moving them around was going to surely result in damage. The simple solution was to store the fenders, hood and other parts in the bed. I built a wood rack the allowed the parts to be stacked. So far, it has worked well.

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

Very sharp looking truck.
Great build you have going here.


If you ever need info on the 8.1 swap,
DirtyLarry is sort of a guru on these swaps.He posts alot in the 4x4 section.Very smart guy.

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

Time for an update. I have managed to make a little progress on this swap. As shown below, I finished installing the new fuel tank behind the rear axle, including the fuel line, return line, wiring for the in-tank pump and a wire to the original fuel gage in the truck.

I also swapped the original vacuum boost Master Cylinder out for the hydro boost MC from the donor 2003 Suburban. It took a little welding and grinding, but in general, it fit in nicely.

Spend some time contemplating my choice to use the original drive by wire throttle body, which requires the use of the also original huge accelerator pedal. After studying the pedal assembly, I determined that it did not need to be huge. the bulk of the pedal assembly is dedicated to the ability to perform an adjustment of the pedal height (in Suburbans with "Driver 1/Driver 2 systems). That feature is not applicable to my 72, to I cut away the unnecessary pedal mechanism and grafted the original pedal onto the now much smaller assembly. It is installed and feels just right.

I also finished striping away the parts on the frontend that were either in the way or being replaced. She is ready to begin reassembly.

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

Quick update. This build is going slow but steady. The 8.1, 4L85e tranny and NP241C transfer case are all mounted and aligned with the diff. No drive lines yet. Working on linkages and accrssories. Transmission shift is hooked up and works perfect. Looking for a shifter stick for the transfer case so I can finish fabing linkage.

I have run into two issues not solved yet - exhaust and power steering. Stock 8.1 exhaust manifolds won't fit. I tried a pair of new stock spec reproductions of 70's era 454 manifolds and they are not close to fitting. Now I am looking for a pair of good used original 454 manifolds.

Power steering - the truck is a factory air original so it is important to make it work with the new motor. Taking Dirty Larry's advice, I installed the accessory brackets on the front of engine from a 2004 Topkick 4500. That also requires switching to the water pump, harmonic balancer, tensioner, A/C compressor and power steering pump from the Topkick. So far, I have found everything but the power steering pump.

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

A couple more pictures. I can't seem to post more than one photo at a time so I'll do a couple of posts.

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

Exhaust clearance

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

Motor mount and crossmember

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

looking good

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

I have a brand new power steering pump for a topkick hahaha

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

Hey Ed,
Any more updates that is looking good!!!!!

Sean

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

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.

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

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

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

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.

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

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.

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

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.

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

Following.

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

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.

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

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.

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

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.

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

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.
Attachment 1599269

Finally I ground all of the welds and generally smoothed things out a bit. Then some paint and undercoating.
Attachment 1599270
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Attachment 1599272

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

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

Sean

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

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!

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

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.

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

Nice work! Glad you can help your dad out!

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

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.
Attachment 1609866Attachment 1609867

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.
Attachment 1609870Attachment 1609873
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