97 454 L29 Vortec into a 80 K25

[Bextreme04]

Finally getting around to working on this project I've had going for a while so I thought I'd get a thread going. Bear with me for a while as I get this caught up with some pics and descriptions of where I'm at already.

I found a 1997 K2500 Suburban with a 7.4L/4L80e combo at 288,000 factory miles listed locally for $800. It started right up and drove under it's own power... sounded decent, and they had a clean title. I offered them $500 and drove it home.

 

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Here’s the donor truck. It was an original Montana truck and looks like it has never had the engine or trans out.

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Here’s the mighty 7.4L Gen VI 454... dirty but complete and running

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[Bextreme04]

First things, first... Everything I think I will use is yanked out including the whole drivetrain including intake, wiring, fuel tank and lines, hydroBoost system, fuse box, windshield washer tank and second battery tray, and a bunch of other stuff.

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[Vbb199]

I've been waiting



Subscribed.

 

[Bextreme04]

The engine/trans will be replacing the original tires 350/TH400 combo currently in my truck

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I’ll be keeping the factory NP205 and just rebuilding it. The tail shaft housing will get modified by Behemoth Drivetrain to accept a tone wheel and 90’s Chevy VSS sensor.

I sourced a longer 2wd slip-joint output shaft for the 4L80e from Global Transmission parts and the figure-8 adapter index ring on the 205 will get machined down by a local machine shop to accept the 4L80e index ring size. It basically needs to be turned down from a little less than 4-7/8” to a little more than 4-3/4”...

 

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I disassembled the engine and sent it out to the local machine shop to get cleaned and inspected back in May or June I think. Also sent the heads to a local builder to get rebuilt as the compression tests and leak down test showed low compression in some of the middle cylinders and leaking intake/exhaust valves on most of the cylinders.

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[Bextreme04]

I've been waiting


Subscribed.

Haha, your patience is about to pay off today! I figured since it was so slow I might as well throw some content out there for us Big Block guys instead of just picking on the diesel guys

 

[Bextreme04]

Heads got cleaned and inspected. Then they installed new guides, did a valve job, surfaced them, machines the guides for positive viton seals and installed 454HO springs with rotator eliminators.


I ended up with just a little more spring pressure(about 30lbs more than stock) and can now clearance up to .620” of lift. The heads don’t really flow any better above .500 though, but that works perfect for the cam I went with. Apparently I didn’t take any pics of the heads, so I’ll have to add them later.

I sent the stock cam out Delta Camshaft in Tacoma, WA for a regrind. It should be fairly mild, but definitely wake up the engine quite a bit.

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[Bextreme04]

Also, while the heads and block were out getting worked on I started working on the wiring. I decided to do an 0411 swap to make the engine run better and allow me to tune it easier. I started to pull apart the factory harness and re-pin to the 0411 computer. I sourced an 0411 computer and pigtails from eBay for $50.

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The 0411 swap wiring came from lextech... he is well know if you are doing these kinds of swaps and shares the pin outs for free with the caviat that you not hand them out to anyone. You can find him and ask for your own info on almost any of the forums like LS1truck.com or gearhead-efi.com

I’m planning on using the factory fuse box from the 97 and combining it with the 1980 cab wiring. I’m going to work up a wiring schematic before I start on that mess though.

 

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I got the engine back from the machine shop a few weeks ago.

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Bored and honed .020 over. New speed pro pistons and Hastings rings. New harmonic balancer, and the whole rotating assembly balanced. The crank was fully in spec, so it just got a polish and I am re-using the rods. Also got a big pile of new parts.

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I started to assemble the engine and check the main bearing clearances with plastigauge(just as a check on the machine shop).

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Turns out they were way too tight. All of the bearing manufacturers list the same bearings for all 454’s. Turns out Gen VI are actually different and have a different clearance on #1 and #5 while keeping 2,3,4 tight. Here’s what I got...

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2,3,4 are tighter than you would normally want on an old school BB, but right in spec for a Gen VI. #1 and #5 should have been around .0025-.0030. I ended up just ordering the factory GM performance bearings for #1 and #5. They won’t be in until next week though, so engine assembly is on hold until then.

 

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So, while I’m waiting on those parts I started working on the intake manifold. I’m not going to run EGR or the Evap canister since my truck doesn’t have any of that now. Those two bosses are big and ugly on the stock manifold and I’m planning on painting it anyways sooo....

Here’s what it looked like originally

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you can see where I started to cut. After lots of cutting, grinding, and smoothing, I’m down to this.

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The threaded hole on top is for a fitting for the vacuum output to the vehicle systems. The pressed fitting next to it is for PCV. The two holes left at the bottom will be either welded shut and then smoothed or I’m thinking of using some POR-15 epoxy putty I have to fill them. They are tapered on both the inside and outside so I won’t have to worry about an epoxy plug getting sucked into the motor or pushed out.

 

[Daveo91Burb]

Definitely following. I'll be interested in seeing how the 0411 conversion works out for you. I'm sticking with a TBI 7427 ECM for now, but if that ends up being too much of a pain I'll consider going the 0411 route.

Apparently there's a guy on Gearhead EFI that's working on a setup to allow easier tuning on the '96 - '99 black box PCMs. No idea where he's at with that yet, though.

 

[Catbox]

I will be watching for sure.
I have already learned something about the engine bearings I did not know.

Plus you have an avitar now.
So grown up...

 

[Bextreme04]

Definitely following. I'll be interested in seeing how the 0411 conversion works out for you. I'm sticking with a TBI 7427 ECM for now, but if that ends up being too much of a pain I'll consider going the 0411 route.

Apparently there's a guy on Gearhead EFI that's working on a setup to allow easier tuning on the '96 - '99 black box PCMs. No idea where he's at with that yet, though.

The biggest issue is definitely tuning. I was originally planning on using the 2156 Express Van OS and doing my own modifications using TunerPro. Then, I ended up remembering that I had a buddy that built an 8.1L and didn't use the factory EFI system. When I talked to him, it turned out he still had the entire factory 8.1L truck coil set and wiring harnesses sitting in his garage and he was happy to send them to me to get rid of them. So then I decided to run the 7.4 as a CNP setup with a 24x reluctor.

Unfortunately that means I need to do some more surgery on the OS. Currently I'm hoping to start with a 2002 12212156 Silverado 6.0L manual trans 4x4 OS(I couldn't find a 6.0/4L80e/4x4 2156) and segment swap the Express van 4L80E trans segments in. Alternatively I can start with the express van OS and copy in the 6.0L engine segment. Then I have to copy all the 8.1L engine calibration tables values over from a different OS, since they never had an 8.1 in the 2156 OS.

I'm using the OBDX Pro Vt tool, PCM Hammer, and TunerPro RT for all of this, so other than buying the programming tool for $69... it's all free. We'll see if the amount of time spent on using the opensource tools makes up the difference in cost from just using HPTuners or EFI Live.

The other nice thing with this setup is that it will be fully OBD2 and customizable, so I can use the same tool to datalog, tune and send data to a tablet or my phone so I can monitor everything I need to while driving without needing to install extra gauges.

 

[Bextreme04]

I will be watching for sure.
I have already learned something about the engine bearings I did not know.

Plus you have an avitar now.
So grown up...

haha, thanks catbox.

All my pics are on my phone, but I'm usually only on here from my computer while I'm supposed to be working... so when I finally got on the site from my phone to upload pics for this thread.... I figured it was probably the right time to update the avatar too!