The Camp 4x4 Bus - 1973 Suburban 8.1 Swap & Build

#1
A few have asked for a build thread on my upcoming project, so, here it is. :wings:
I'll also be posting photos regularly on my Instagram account - @Camp4x4

Background

For the last few years I've been building a 1987 Chevy Suburban into a fantastic truck for camping and moderate to extreme off roading. This, is Boom Boom:



For quite a while I've been unhappy with how the 350 TBI handled the big truck, especially when it was full of camping gear. After reading Larry's 8.1L Vortec swap thread on CK5.com I got it in my head that that's what I wanted for Boom Boom. One $500 Chevy 8100 later and I was well on my way. Now, this being California I was well aware that getting such a swap by the CARB refs was going to be tricky. But, it was a challenge I felt would be worth it. After talking to a ref last summer I was confident that I could eventually jump the many, many hurdles they were going to put in my path. Until...

Having secured a motor and a Howell flashed PCM, along with and the VIN that was programmed in to it, I called up the ref's again to get more specifics. Unfortunately they offered not hurdles, but a complete and total wall. I was told that there was a new memo that had been passed down at the beginning of the year, which stated any OBDII engine swaps must be accompanied by an invoice from a dealer stating the PCM had been flashed to OEM specs. The effect of this is that all OBDII swaps into vehicles other than the make and model the PCM originally came from would be impossible.

For those unfamiliar with swaps of OBDII engines, here's the short version of why: there's 2 things that primarily need to get flashed out of a PCM when doing a swap into a vehicle for which the PCM was not original. 1) The Vehicle Anti-Theft System (VATS) - this is the system that reads the chip keys used in newer vehicles. 2) Nuisance codes - these are check engine light inducing problem codes that come on because of things other than an engine problem. These can be things like your tail light is out, or other body related issues. Since the vehicle receiving the swap would have neither the correct key, nor all the various body sensors required to not trigger these nuisance codes, the vehicle wouldn't start, and if it did the check engine light would come on. That's an immediate fail for the refs.

Now, yes, there are VATS bypass boxes, so that's potentially not a deal killer. But the nuisance codes... I have yet to find anything that can emulate the various sensors to bypass those.

"What if you just get the PCM flashed by a dealer, then send it back to Howell to get re-flashed," you ask? Well, if I'm a ref I know that an OBDII swap won't work without those things. So my FIRST question when the truck starts up and doesn't throw a check-engine light is, "how'd you get that to work without re-flashing the PCM (which you're not supposed to do)?" Without a good answer I'd be hosed.

So, I figured, if CARB wants me to keep that crappy old 350TBI in there, fine. I'll just find a truck they don't care about and do the swap in that.

Now, I'm in no position to simply sell Boom Boom as it sits and redo all the work and money I've put into it on another truck, plus I love the square body 'Burbs. So the best thing, I figured, would be to find a truck that I could swap most of the good stuff onto. Since Boom Boom is an '87, that left a 3-year period of Chevy Suburbans that are in both the smog-exempt category and the '73-'91 generation.

The search began pretty much as soon as I found out the bad news from CARB. SearchTempest.org is a fantastic resource if you're trying to search Craigslist across multiple states. I found a few trucks that met most of the criteria: '73-'75, barn doors, minimal rust, hasn't yet been modified a bunch, and under $2,000. But, none totally fit the bill. I came close to pulling the trigger on one, but the rust was just a little too much for being right at the top of my budget.

In the mean time I'd been messaging back and forth with Larry, from the CK5 swap thread, about my whoas. Recently I happened to mention that I'd decided to go the route of finding a good '73-'75 'Burb. He quickly said he may know a guy with one for sale in AZ - one of his wheeling trip buddies - but he was 99% sure it was a tail gate version. Well, its a good thing Larry isn't a gambler, because it turned out that not only was the truck a barn door model, but it had factory AC, totally manageable rust, was a '73 and the guy only wants 1500 for it. Not only that but the interior was immaculate!

Turns out this particular Suburban had been in Larry's friend, Don's, family from day 1, and they've taken terrific care of it through the years. Though he didn't have it listed anyway, I guess word had gotten around that he wouldn't mind parting with it. Good thing for me!

Within a week of talking to Don I was in a dually with a trailer in tow headed to pick up The Bus. 1500 miles later I've got her sitting in the shop ready to get to work! :victory:



The Plan

Of course, as soon as I'd hung up with Don and new I'd be buying the truck I started ordering parts. I'd already amassed a pretty good cache of stuff to go with the 8.1 but I'd sort of stopped buying things when I'd got the bad news from CARB. But now, game on! So, here's the plan:

Engine: 8.1L from a 2006 Chevy Suburban that'd been in a front end collision. Oil pan was cracked but everything else looked good.
Trans: 4L80E - perfect upgrade for the TH400 that I'm used to and that I'm geared/tired for. I picked this up on my way to AZ actually. Rebuilt by ATW in Rancho Cordova with a shift kit and all the good beef-up stuff. Plus an HD torque converter with stock stall.
Axles: I'd just put together a bad *** Dana 60, so that'll come over from Boom Boom, along with the 14 Full Float rear. The Dana 60 has ORD high and crossover plus hydro assist. Both axles are geared at 4.56, and the Dana 60 has a torsen LSD while the 14 still has the stock gov-lock. Discs all around.
Transfer Case: I'll probably just be keeping the NP203 that I expect is in the '73... budget is getting a little tight, so for now I think it'll be fine. Magnum Box and NP205 are probably in the future.
Radiator: 4-Core replacement for a Big Block equipped '80s Chevy. This will of course have an e-fan. I decided to go with a single 16" fan. Still have to figure out the shroud.
Suspension: I'm using ORD's shackle flip in the rear with new, stock height 8+1 HD springs. In the front I picked up some Pro Comp HD lift springs. With the heavy *** big block I wanted to make sure it wasn't under sprung and mushy. I'm equally if not more concerned about on road driving as offroad. If I have to sacrifice a little flex for control on the highway I'm okay with that. The Pro Comps have a spring rate of 526 lbs./in which may be a bit stiff... but we'll see. I'm also using ORD's HD shackles front and rear.
Engine Crossmember / mounts: ORD's high clearance crossmember and HD motor mounts
Transmission Crossmember: I figured I'd match the tube look of the ORD engine crossmember with a tube trans crossmember. I'll have to move this anyway since the 4L80E is quite a bit longer than the TH350 that I think is in the '73 now. Classic Parts Online has a tubular crossmember that seems like it'll be perfect.
Steering Column: I like cruise control, and I like the u-joint only steering shaft options available for the late '80s steering columns, so I'm going to find a used one in good shape from Craigslist or Pick-n-Pull so I can have those niceties. Should swap right in.
Shift linkage: I'm going to try using the Lokar Steering Column Cable Shift Linkage ACA-1804 rather than try and hack up the stock linkage bars.
Speedo cable / VSS: Since I'm not changing up my gauges, but the PCM is going to need a VSS signal out of the transfer case, I'm going to try Dakota Digital's solution: Their cable pass-through pulse generator paired with their Universal Speedometer Signal Interface. The pulse generator should thread on to the t-case, then allow the speedo cable to thread onto the other side of it. In the middle it uses the rotation to generate a VSS signal. From what Dakota Digital told me the PCM is expecting a 24,000 pulse-per-mile signal, while this little guy only does 8,000. That's where the USSI comes in. It acts as a signal multiplier to give the PCM the right number of pulses so everything works right.
8.1 Accessory Brackets: I'm going to be following Larry's advice of switching up the accessory brackets to the Workhorse configuration so I don't have to do any frame chopping. I'm not 100% sure I have all the right ones, and probably won't be until I have them all on but that's the plan. I'll post part numbers as I find out what works.
Gas Pedal: According to Raylar Engineering and Wikipedia the accelerator pedal from a 1994-2000 K2500 6.5 Turbo Diesel will work with the drive-by-wire throttle system. I'm keeping this rather than going cable because I'm not a huge fan of the kind of klugey nature of switching the 8.1 over to a cable throttle body. Though with the pedal assembly being $250 on Rock Auto, and none of these trucks showing up in wrecking yards around me... I'm kind of re-thinking that.
Other stuff: I'm sure I'll be modifying the driveshafts' lengths to patch the new driveline. I'm going to leave the interior alone for now except to put in a proper modern head unit and amp. Eventually, though I hate to do it, I'll be putting in some bucket seats and a center console. The bench is just not safe. Electric door locks, windows, etc are all in the plan for "sometime". And I'll definitely be swapping over the roof rack, RTT, ham radio, CB, antennas, lights and winch bumper.

The goal is to keep Boom Boom operational so I can sell it for something instead of just scrapping it. Hopefully someone will want it... :-/
 
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#4
Picking up the project gallery

Here's a bunch of photos from picking it up in Flagstaff. That was a hulluva trip. Drove out from San Jose on Saturday. Picked up the truck and trailered it back on Sunday. 14 hours each way. Sheesh. Still less of a headache than dealing with transport brokers. Screw them.

Don was a really great guy, and I hope to join up with him and Larry for a trip once The Bus is ready.

















 
#7
Wow, this is going to be a great build. Would a diesel version have been a viable option to avoid California smog checks since once you registered it, you don't have to have it smogged again?? I'm assuming this is still in effect but who knows with CARB.

I will say that the old body style with the round headlights looks the best of all Subs. I know my 1985 with the 4"x6" headlights had some of the worst light output of any vehicle I own. Even my 1991 Sub with those skinny little headlamps had better lighting. But nothing beats the big 7" round lights, especially if you upgrade to the Hella Vision Plus DOT legal versions, had those on my Jeep and they were awesome for the price.

I also have a spare set of rear barn doors should need them....I'm in Vacaville.

Good luck with the build.
 
#8
As you are from California - I'll help you understand what you're looking at



that is a thing called "rust" - it's a terrible affliction that everyone else has to deal with and has been known to poison marriages, cause children to start cussing, and bankrupt entire families. While it appears all innocent on the outside of that panel, if you see it there, you should know that you will start finding it throughout the vehicle and it will jump to other, otherwise pristine vehicles.

I'm surprised they didn't turn you back at the agricultural station on the Cali border. With that said, it is good that you've brought that plague into California - they need a little rain with all that sunshine.

joking aside, since your parts-rig is 3/4 ton - you may be better off 'simply' swapping the running gear from one to the other. 3/4 ton frames are heavier-duty - add to that the 1/2 frames are prone to cracking at the steering box and it's an even better upgrade
 

locrwln

Expedition Leader
#10
Nice survivor. It looks like it has the stock Spicer front hub-locks. If so, it most likely has the NP205. The NP203 had drive slugs and not dials.
.
Also, can you take a picture of the SPID? I love seeing how they came optioned from the factory.
.
Jack
 
#11
As you are from California - I'll help you understand what you're looking at



that is a thing called "rust" - it's a terrible affliction that everyone else has to deal with and has been known to poison marriages, cause children to start cussing, and bankrupt entire families. While it appears all innocent on the outside of that panel, if you see it there, you should know that you will start finding it throughout the vehicle and it will jump to other, otherwise pristine vehicles.

I'm surprised they didn't turn you back at the agricultural station on the Cali border. With that said, it is good that you've brought that plague into California - they need a little rain with all that sunshine.

joking aside, since your parts-rig is 3/4 ton - you may be better off 'simply' swapping the running gear from one to the other. 3/4 ton frames are heavier-duty - add to that the 1/2 frames are prone to cracking at the steering box and it's an even better upgrade
As the shirt attests, I'm a Chicagoan, so I've seen rust! :Wow1:

But yeah, it is definitely something I'll be looking out for as I start taking things apart. As for what I can see now, it is all in the white area of the paint and not really to the point where panel replacement is needed. So, my plan is to fully clean the infected areas, anti-rust primer it, then paint the whole white section with bed liner to seal it and toughen it up against the inevitable branch hits it'll be taking. That should pretty well hide any bumps and bubbles left from the cleaning.

I have heard that the 1/2 tons' frames were slightly thinner... and I'd considered doing a body swap... but that would basically mean 2 engine swaps if I wanted to keep the '87 running. Or... scrapping the '87. Which I don't _want_ to do. I have a steering box brace from ORD I'm going to put in. No boxing is in the plan at the moment... ugh... decisions.

Wow, this is going to be a great build. Would a diesel version have been a viable option to avoid California smog checks since once you registered it, you don't have to have it smogged again?? I'm assuming this is still in effect but who knows with CARB.

I will say that the old body style with the round headlights looks the best of all Subs. I know my 1985 with the 4"x6" headlights had some of the worst light output of any vehicle I own. Even my 1991 Sub with those skinny little headlamps had better lighting. But nothing beats the big 7" round lights, especially if you upgrade to the Hella Vision Plus DOT legal versions, had those on my Jeep and they were awesome for the price.

I also have a spare set of rear barn doors should need them....I'm in Vacaville.

Good luck with the build.
Sooooo... diesel and smog... I want to start by saying I wanted this truck to be completely out of any grey areas in the smog laws. What I could have done is grab a pre-85 diesel 'Burb to do this all in. Pre-85 diesels are also smog-exempt. HOWEVER, you can only swap like for like engines. So you aren't supposed to swap a gas engine into a diesel truck and vise versa. But, since pre-85's don't actually get smog checked, the likelihood that anyone of authority would ever notice is minimal. Should you want to sell the truck, however, you'd need to find a buyer who's also comfortable operating in that grey area and continuing the registration as a diesel. I'm sure that isn't too hard, but... you know...

I'll check out those Hella replacement lights... definitely something I've loathed about the '87.
 
#12
Nice survivor. It looks like it has the stock Spicer front hub-locks. If so, it most likely has the NP205. The NP203 had drive slugs and not dials.
.
Also, can you take a picture of the SPID? I love seeing how they came optioned from the factory.
.
Jack
I will be PUMPED if it has the 205! I honestly didn't look underneath or at the RPO codes. Happy to snap a pic of those when I check it out. MF4 would be 205 and NP8 is 203, yeah?
 
#14
Nice survivor. It looks like it has the stock Spicer front hub-locks. If so, it most likely has the NP205. The NP203 had drive slugs and not dials.
.
Also, can you take a picture of the SPID? I love seeing how they came optioned from the factory.
.
Jack
Okay, so here's the original build sheet. Was in the original owners manual in the glove box. No RPO code sheet in the box though. My buddy who's at the shop and took the picture didn't poke around many other places so I may have to hunt a bit to find more.

 
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