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Old 12-21-2015, 02:00 PM   #1
Ackattack
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Join Date: Aug 2002
Location: Valley Center KS
Posts: 3,525
5 day ls swap...can it be done

I'll be embarking on putting a 4.8L engine into my 1990 K3500 ext cab over the next few days. I have a "plan" on a spreadsheet and I hope to be able to complete the project in 5 days of work (Christmas will be in there, so it won't be 5 consecutive days).



Currently the truck is has a 454 in it, TH400, transfer case (don't know which one...not part of the build), and 4.10 gears.

The 454 runs like an absolute turd. Even with the 4.10 gears I can barely spin the tires on GRAVEL. I've checked and checked the sensors and everything else and there doesn't seem to be anything wrong with the engine from a control standpoint. It just seems that the engine is shot, blowing a bunch of blue smoke out, etc, etc. Not to mention I don't really like the TBI engines.

You may be thinking that a 4.8L is kinda small for a 1 ton truck, and you're probably right, but I got is for $300 buck, so why not. We recently started a metal cutting business (www.AckermanMetalDesigns.com) and bought this truck cause it has a flatbed on it to go get sheets of steel. I may pull a trailer with it occasionally, but I'm not overly concerned with towing performance.

However, stock for stock, the 4.8L has about 30 more HP than the 454 does, though it is down on torque. However, with the 4.10 gears and no OD, I don't think it will be a problem, and the 4.8L should like the extra rpms. I'm hoping to go from 7.4mpg to something a little more respectable like 14, but we'll see.

I do have a 4L80E, but I would have to get new driveshafts and I really don't think it will be that beneficial considering that it is only a 4.8L in a relatively heavy truck.

This isn't the first engine swap I've done, so I don't expect any issues, as long as I'm not waiting on parts. I am going to make the motor mount adapter plates, exhaust flanges, and EGR blockoff plates. Not too hard when you own a CNC plasma table
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