88GMCtruck's 98 Silverado Towpig Build: "Black Fox"

[DanteGTZ]

Finally making some actual progress as best as my schedule allows. First picture is the Cummins all done, less the accessory bracket. I'm very happy with the way it turned out. Can't wait to see how much power it actually makes with all of the upgrades.

Got the 454 out last Monday, sold it today. The clutch, flywheel and bellhousing are available if anyone needs them. The clutch is still in fantastic shape.

I need to make a couple modifications to the truck in preparation for setting the engine in. The factory mount pads needed to be trimmed down a bit to make room for the oil pan. I also had to countersink a few of the front diff bolts to make room. I also had to make a few relief cuts in the trans tunnel/firewall and fold back the seam where the two come together.

I still need to drop the transmission and then degrease/paint the bay and frame before I start fitting the Cummins. Once the motor is sitting where the mounts locate it, I'll get the transmission bolted up to it and see how far back it will need to go. I'll have to drill new mounts for the trans/xfercase crossmember and extend the factory shifter hole back a little bit.

That's where I'm at currently. I'm very happy that much of the wiring mess won't be reused. I labelled everything as I unplugged things but I believe I'll just reuse the oil pressure sending unit and coolant temp sensor plugs.

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[Supercharged111]

I remember welding the bits into my truck that you removed. My flipper was an incompleted Cummins swap. I remember there was an issue with the NV4500 interfering with the floor, the way it was set up they couldn't get it up all the way. Could have been the engine hit the cowl, I forget.

 

[DanteGTZ]

Attempted a test fit of the Cummins tonight. Left and right fitment are good as far as space is concerned but the bellhousing and trans tunnel are definitely going to be a tight fit. So far I've not had to cut out any of the "V" bracing at the front of the frame and it looks like I'll have decent clearance.

The SSOR mounts haven't quite fit as well as I'd hoped (especially for the cost!). If one side is bolted down to the frame, the other side is about an inch off from lining up. I messaged the manufacturer so we'll see how it goes.

I've still got to order an AC conversion kit and will likely go with Adventure Vehicles NW. I wanted to wait to see exactly how the stock Dodge setup would work but there really isn't any room for the compressor in the stock Dodge location in the GMT400 frame.

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[DanteGTZ]

Quick update. Progress has been very slow. I had a hell of time trying to get the SSOR mounts to fit and eventually gave up on them. I contacted Joel @ Adventure Vehicles NW and ordered a set of his conversion mounts. They went in quickly and the engine is finally bolted in and supported by the chassis.

The transmission had to move back 4" and therefore I had to drill new holes in the frame. The transfer case is going to be very close to the torsion bar crossmember. I'm going to pull it down tomorrow to gain clearance for the transfer case to go in. We'll then find out if it has to be modified at all.

I still have a laundry list of items to finish up including throttle cable, starter, oil and temp sensor, fitting the radiator & intercooler along with exhaust. I cannot wait to drive this truck again. It's been way too long.

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[Supercharged111]

It's so tight in a stock CCLB with that transfer case you'll probably need to gain yourself 4" of clearance or drop the member to get the case in.

 

[DanteGTZ]

Made some more progress on the Cummins swap recently. Had to remove the torsion bar crossmember to get the transfer case back in.

The entire drivetrain moved back 4" overall which made the xfer case contact the torsion bar crossmember. I had to extensively clearance the crossmember and will be reinforcing it before reinstalling it.

I got the driveshafts back today and will install tonight. New u-joints and carrier bearing as well.

I started on the wiring this past weekend and unpinned the unused wiring (MAP, MAF, O2s, etc). I'll have to lengthen a few wires/plugs but that'll be easy. All in all I think I removed ~35 wires from the harness.

I replaced the GM throttle cable with the one from the donor truck and it bolted up no problem. It's a little bit long, but it'll do. Same with the cruise cable. I was able to reuse the original GM cruise cable on the Cummins linkage.

Also removed the in tank fuel pump and replaced it with a section of submersible hose and a right angle elbow to act as a draw straw from the tank. Shortened the hard feed & return lines between the engine and fuel filter, flared the lines and used a small section of rubber hose to connect the lines to the engine. Came out really nice and clean.

Word to the wise, fluid for an NV4500 is EXPENSIVE. I paid ~$35/qt (needed 4.5) from my dealer. I know Redline, RP and Amsoil all make equivalents, but I didn't want to risk any synchro damage. If I'd have known how expensive the fluid was, I would have saved it as it looked decent when it came out.

After the fuel system was all done, we hooked up the starter and solenoid wiring. The engine fired right up, no problem. I still need to install a downpipe and exhaust (which will arrive tomorrow). I went with a 4" Cummins downpipe and a 4" complete system for a 6.5 GM from Diamond Eye. I'll have to do some modifying to get it all liked up,but once the downpipe connection is made, the rest should bolt up w/o modification.

I still have to work on the clutch hydraulics, intercooler (or temporary bypass), cooling system and AC setup. I'll also be building new battery cables to accommodate 2 batteries. Dave gave me an additional battery tray for the driver side, so that was a bonus.

For the clutch, itd be ideal if I could use the complete Dodge setup including master, slave and clutch hose. I'm not 100% sure if the Dodge master can be mounted to the existing GM style twist lock in the firewall. If not, I may buy a newer (smaller bore) Dodge slave cylinder and run the OEM GM master. I know people have had mixed results with it, but the newer Dodge slave bore is just slightly bigger than the GM master, whereas the 94-98 style Dodge slave has a much larger 1" bore. I think that's where most people have run into trouble.

Anyway, that's where we are at so far. I cannot tell you how excited I am to get this truck running again. I absolutely love this truck and it's been wayyyy too long since I've gotten to enjoy it (mid-November).

Brian

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[Supercharged111]

Have you sourced a diesel filler neck yet? I'm hoarding some piddly crap like that from the flipper that seems like I'll never finish in hopes of swapping mine over.

 

[DanteGTZ]

Have you sourced a diesel filler neck yet? I'm hoarding some piddly crap like that from the flipper that seems like I'll never finish in hopes of swapping mine over.

I am still looking for the diesel filler neck. I've been unsuccessful in finding on locally.

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[Cokeman95]

Have you sourced a diesel filler neck yet? I'm hoarding some piddly crap like that from the flipper that seems like I'll never finish in hopes of swapping mine over.

What's the difference on the filler necks?

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[OutlawDrifter]

What's the difference on the filler necks?

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Bigger hole for the fuel nozzle.