Going to try to address specific build items now that the stress of getting it running again is past. Today, I’m going to focus on the engine layout. With the hole cut in the hood, I’m guessing there are some raised eyebrows amongst the society members.
So. The details: Motor: this is a 1999 LM7 (8th digit “T” in the VIN) GM 5.3L V8. While it’s called an LS, there are lots of variants. This motor was typical in the base Silverados, Yukons, etc. the LS motors in Corvettes, etc. is shorter but wider- this is taller and narrower, from what I understand.
Adapter: Mark’s 4wd LC bell housing to LS adapter, purchased in conversion kit from Advance Adapters, along with clutch plate, pressure plate cover, and engine mounts. The Mark’s 4wd adapter includes the outer housing, a sleeve for the throw out bearing/clutch fork pressure bearing, and a splined adapter to go from the 10 spline H41/H42 tranny input shaft to the GM spline on the GM clutch plate. This adapter is a bit shy of 5 inches deep and mounts between the bell housing and the engine block. The extra depth pushes the engine forward in the bay to move the engine out of the narrow indent in the firewall, meant to accommodate the narrower inline 6 F series motors. By using this, the rest of the drivetrain can stay where it is, and driveshafts don’t need to be re-sized.
Engine brackets: these are a 2-part universal mount from Advance Adapters. They allow for about 3” of play side to side depending on which hole you run the bolt through. Vertically, there isn’t any adjustment, but they come with (2) bolt holes for placement.
When we got the motor positioned in the bay, we noticed a couple things:
1. Motor is not centered- it is shifted to the driver’s side. Not sure why that was the case with the 2F, but with the 8” deep oil pan on the LM7, we needed that layout to avoid conflict between the pan sump and the front drive shaft mounting flange off the back of the differential (4th photo with motor centered- not good!).(5th photo with motor shoved as far to the left as possible- better but still close!)
2. Motor mounts needed to be mounted as close to the bottom of the frame as possible. The bottom of the bottom bolt is pretty much touching the inside face of the bottom of the tube. Even so, when we bolted up the bell housing, we had to put spacers between the bell housing mounting brackets and the bearing bushings. Good thing the kit came with solid spacers that were about 1” tall, exactly how much we had to raise the tranny up to meet the engine, like they knew this was going to be the case!
In order to raise the bell housing up, I had to cut out a portion of the fire wall. Right now the bolting flange of the tunnel cover touches the pan floor, but the top of the tunnel cover is sitting right on the tranny housing. And I have to re-fab the initial part that was not removable. I’ll also be fabricating a riser to lift the tunnel up a bit for clearance.
So…knowing that I have a big hole in the hood to deal with, I am wondering if I could have done things differently: fabricate additional frame structure below the existing frame to mount the engine brackets lower? Might have saved me the Mad Max hole in the hood, but I think it would have exacerbated the oil pan /drive shaft proximity concerns and would have made the power steering pump and AC harder to deal with (real tight clearances here as is). I think the engine is where it needs to be and I just need to get creative with my hood scoop. I wonder if people using this Advance Adapters kit for an FJ40 LS swap have run into the same issue.
