7.4 Vortec help??

[Kapote]

Im new to this whole idea of a 7.4 swap... I have a 2000 bus with a 7.4 Vortec in it. really low miles on the bus, and now im thinking of putting it into my 1984 K20. I need to know what is the biggest things I will run into... I feel that wiring is gonna kill me.... So what all do I need from the Wiring harness so I can run the fuel injection??? any help will be appreciated.

[BR3W CITY]

The 7.4 your talking about I assume is the "Vortec7400"...which was a medium and heavy duty gas truck engine that was in stuff like c3500's. In your case, a bus (Bluebird, Navistart etc had GM contracts for these engines, as well as diesel options).

Its not really an LS motor of any sort, its a fuel-injected 454 which exists on the classic big block chevy architecture (sorta like the 8.1's that were popular in the same segment, and in some cases still are). I've never swapped a 7400 into anything, but since its on the bbc platform, the 8.1 swap info on the web is probably our best start.

lt1swap.com has an 8.1 section with pics and descriptions of his project. He also is a great resource for wiring and ecm pinouts.

In terms of putting one into your truck thats possible, and will provide the big torque I assume you might want in a 4wd heavy truck. IMO, when swapping any obdII engine (and wanting to keep the computer and efi), its worth having a harness made. Starting with a clean new harness makes terminating every connection much easier, and the added costs are usually offset by the lack of wasted time, redoing things, wasted material etc. If you have it in the budget, its worth it.

If your running and o/d trans then take a look at some of the LS swaps that are 4wd. While the engine wiring etc will be different, they also will be running overdrive trannies. The extra length, vss wiring with the transfer case and some other 4x4 specific things have been addressed and those guys can save you the headaches. All swaps have tight header clearances, 4x4 guys get it tough as well.