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Discussion Starter · #1 ·
Been wanting to tackle this sort of project for awhile and finally pulled the trigger. Picked up the suburban a week ago and my 4BT arrived late last night. This truck will be primarily for driving around town and very little light towing. I chose the suburban because the price was right and I figured the drivetrain, radiator, suspension, etc. are already beefy enough for the 4BT as it had the 454 stock. The 4BT came from a chevy step van with the TH400 still attached.

It seems like the gearing will make or brake your performance and mileage on these conversions. I've been working through the gear calculations and making sure I'm on the right track. I've spent a lot of time reading all the info on here but I'll throw out some questions that I've been contemplating as I begin this journey...

1. AFTERMARKET TRANS CONTROLLER Which aftermarket trans controller is the best? Compushift, TCI, Baumann, etc... Or are they pretty much all the same?

2. TORQUE CONVERTER - Will a torque converter from a 6.5 Chevy Diesel bolt up to my engine with the bread truck adapter plate and the 4L80E? What is the best option for a TC for this 4L80E setup. What's the ideal stall speed?

I know a lot of you guys have a wealth of experience and I appreciate your feedback. I'll try to get some pictures up here later this week.
 

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Discussion Starter · #2 ·
Road Speeds with Stock 4.10 gearing

The truck has 4.10 gears stock and 285/75/16 tires. It seems like this will work out ok with the trans ratios but probably better to swap in some 3.73 gears later (or it seems that 3.42's may be available?)
From the gear ratio calculator on grimmjeeper.com here are the speeds I am coming up with for the 4L80, 4.10 axles:

Road Speed at Given RPM in Miles Per Hour
Gear 750 RPM 1750 RPM 2500 RPM 3000 RPM
1 7 17 24 29
2 12 28 40 48
3 18 42 60 71
4 24 56 79 95
 

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If it had a 454, it should have the same converter the 6.5 used, it should work fine with the 4bt. Does your th-400 converter bolt up with six bolts, if it does the 454 converter should bolt right up?

I think I'd leave the 4.10's in there, especially with those tires and driving around town.
 

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Discussion Starter · #4 ·
I need to take a look at the converter on the 400. I haven't separated the TH400 from the cummins yet to take a look.

I guess I just assumed that the 454 TC would have a higher stall speed than TC for the 6.5 TD? I've read that anywhere from 1100-1400 is good for the 4BT.
 

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Discussion Starter · #6 ·
The motor

Here's some shots of the engine I plan to put into it. Still has the TH400 attached. This one came with the water intercooler. I haven't seen many with this, will have to see if it will fit under the hood. The guy i bought it from drove it back from the factory 70 miles or so and said it had a slight miss at idle that smoothed out once it was up to speed. He thought it may be an injector or head gasket. Does this sound right?
 

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Looks like a great project. Water to air aftercoolers aren't too rare. You have a 4bta which should be 120hp. If hood clearance isn't a problem you should be ok. Otherwise change to an air to air unit mounted in front of the radiator. Your engine speed calculations appear to be right on. If most of your driving is city then the 4.10 gears won't be an issue. The overdrive probably won't be used much for that. If you were doing a lot of interstate driving then you might want a high rear gear. The sweet spot for these engines seems to be around 1800 rpm. As for the engine, it seems to be a good practice to at least partially tear it down to make sure there are no unpleasant surprises. Want to fix the KDP and put in new gaskets and seals. Check the head for cracks, bent valves, and make sure there is no cylinder wall damage. Also check the main and rod bearings. It's a lot easier to do this with the engine out than after you've got it all installed. Might want to have the injectors rebuilt. CrewCab59 is good at that. Once you get it in the vehicle it is nice to only change oil and filters for the next couple hundred thousand miles.
 

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I am currently doing a similar swap. I am putting a 4bta into an 88 suburban 2wd. My aftercooler is not going to fit so I am turning the hood into a cowl. I actually rebuilt the whole thing and having it running on a strand in the garage. I am going with the 4l60 (non electronic) for now and want to upgrade to 4l80e in the future. I will probably get the Baumann control due to price and people seem to like them. You got a pretty burb. I just like how handy they are and I want respectable gas mileage. I have bracket for the ac to use my compressor that I purchase from autoworld. It ran about 300 bucks and I am going to use the liquid filled mounts. I have smaller tires, but I have 3.42 gears. I have a few pics up and a thread started of my own. I bought a 1200 stall from PATC. Sounds like people are going from 1000-1200 with these. Are you going to use the hydrobrakes? I don't even have my lines primed yet and they feel stiff. It's probably my imagination. These engines seem to be readily abused. When I got mine it would start but not throttle up and just belted out smoke. The head gasket seemed very worn and there were large grooves in the cylinders. Now after a total rebuild it puts out some grey smoke but it starts to clear once it warms. Well have with it. I am getting excited about the install tommorrow!
 

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Discussion Starter · #9 ·
Update... The grille and front end are off. The 454 is out. I set the 4BT in there initially to check the clearances. Good news is that it looks like the chevy bread truck mounts are going to pretty well line up with the angled mounting plates in the Suburban. I may need to space them up 1.5 to 2" or so. Want to get my pretty much trans level. I had to cut the lips off of the suburban mounting plates (about 1" or so) to get the block to set down between them. Bad news is that the oil pan is going to need some serious modifications to clear the front differential. Saw that another guy on here was able to do it on his 4x4 IFS Suburban so it is possible. Just going to take some more time I guess. Will have to start cutting on the pan and get it to clear. Does anybody have a template for modifying the pan?
Engine - I pulled the head off the engine to take a look and found some scoring on the front cylinder, also noticed that it has a different style injector in it. The other three have three little ribs on the inside where the fuel line connects where this front one just had a regular hole. The scoring is bad enough that I might need to bore this cylinder. I need to pull the piston and see what it looks like. Don't see any marks on the deck or head gasket so at this point I am assuming it is stock bore, will measure to make sure. Been reading some other posts that some guys are able to smooth the grooves out enough with a rigid hone depending on how bad they are.
Will try to post some pics next time.
 

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Discussion Starter · #10 ·
Update... Ended up using the other engine I had. Pulled the heads to check it out and it looked much better than the first.
Got the injectors cleaned/rebuilt.
Had the head checked out and the valves ground.
Cutting and welding the oil pan to clear the 3rd member and diff proved to be one of the most time consuming challenges on this project so far.
Mounts were surprisingly close to the stock mount pads, just had to space the drivers side up about 2 inches to get the proper tilt to match the bread truck adapter plate.
Wired in the compushift controller. Using the stock converter from the 454 in the 4L80E for now.
Sorting out wiring to try and get the Tach and gauges working.
Hope to fire it up for the first time later this week.
Looks like the intake horn may stick up past the hood an inch or so. May have to cut down the spacer a little bit or put a cowl induction hood scoop on this thing....
 

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BigSlim, I doing the same with a 97 2500 4x4 Suburban and a 6bt. I'm on the north side of Austin. Keep up posted on progress.

Greg Youens
 

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Discussion Starter · #12 ·
Update... Got it fired up and moving under its own power in the last 3 days. It sounds great and is surprisingly smooth. I was expecting the worst from what I have read about the things vibrating with an automatic trans, but its really not bad at all so far.
Trying to get it ready for a 900 mile drive to IL leaving on Wed morning. Had to modify the firewall slightly with the sledge to get the down pipe to clear. Haven't got the tach or coolant temp gauge hooked up yet. The alternator on the 4b has a wire for the tach signal but I'm not sure where to hook it up to the stock harness. Have to find the wire in the old harness for the coolant temp sender too.
Looks like i've got a drip of fuel coming from the back side of the pump closest to the block. Will have to deal with this after the trip I think.
Need to play around with the compushift programming and try to get it roughly tuned in for the drive north.
Its coming down to the wire here...
 

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Hi Greg, how far along are you on your suburban project?
I pulled the frame out from under the Suburban and have been cleaning the frame up, cutting all the front suspension brackets off for Solid axle swap. I orginally planned on using an NV4500 but now thinking about going back with the Automatic. So I hadn't really made a lot of progress on engine swap.
 

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Discussion Starter · #15 ·
We made it to IL!
I put about 30 miles on the rig before heading 900 miles north in it. We had it loaded completely full and pulling a 4x8 trailer. It ran smooth and lulled my baby girl to sleep. I played around some with the settings on the compushift on our way to get the tcc to engage when I wanted but I still need to take some time and figure out what all the other settings do. We ran 70mph more or less the whole way on interstate. Coolant temp didn't move from ~185. EGT cruising about 800-900 and up some long hills in Missouri it peaked at 1200. Boost on those stretched maxed at 15psi. The only trouble we had was when one of the rear tires threw the tread off in the middle of missouri. Thankful that we got stopped safe and it didn't tear up too much, just dented and scratched the rear quarter panel a little. Mileage was a little lower than I was hoping for at 18.5 average. I'm curious to see what it will do without the trailer behind it. Seems like she really would have rather been running around 60-65mph than 70. We are really pleased with this truck so far and looking forward to a completing a few more things on it this summer. Again, I gotta say, this is smooth, no issues with the vibration at idle that others have had. Here's the to do list between travels in the rig this summer.

-Mount the intercooler
-Figure out how to mount the AC compressor
-Clean up the wiring harness
-Fix the damage from the tire blow out
 

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We made it to IL!
I put about 30 miles on the rig before heading 900 miles north in it. We had it loaded completely full and pulling a 4x8 trailer. It ran smooth and lulled my baby girl to sleep. I played around some with the settings on the compushift on our way to get the tcc to engage when I wanted but I still need to take some time and figure out what all the other settings do. We ran 70mph more or less the whole way on interstate. Coolant temp didn't move from ~185. EGT cruising about 800-900 and up some long hills in Missouri it peaked at 1200. Boost on those stretched maxed at 15psi. The only trouble we had was when one of the rear tires threw the tread off in the middle of missouri. Thankful that we got stopped safe and it didn't tear up too much, just dented and scratched the rear quarter panel a little. Mileage was a little lower than I was hoping for at 18.5 average. I'm curious to see what it will do without the trailer behind it. Seems like she really would have rather been running around 60-65mph than 70. We are really pleased with this truck so far and looking forward to a completing a few more things on it this summer. Again, I gotta say, this is smooth, no issues with the vibration at idle that others have had. Here's the to do list between travels in the rig this summer.

-Mount the intercooler
-Figure out how to mount the AC compressor
-Clean up the wiring harness
-Fix the damage from the tire blow out
I get about 19mpg in the city with a 2wd suburban 4bt zf5 unloaded. It seems no matter my driving habits.
 

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Discussion Starter · #17 ·
Wiring Questions:

1. If I connect the Compushift TSS signal replicator wires to the connector that I unplugged to connect the TSS sensor to the compushift will my speedo work again?
2. Where did the ECM get the original signal for the tachometer on the 7.4L? Crank position sensor? Can I connect the alternator R wire from the 4b alternator to this or do I need some sort of signal converter?
 
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