Typically when LS swapping the GMT400 you'll need to adapt your fuel system to the LS's required 58 PSI fuel needs, engine, wiring harness to include the transmission and then have it spliced and ran into the original harness and modified to what the truck can utilize for gauge cluster readouts. I just finished LS swapping my friends 96 C1500 and we used a 2002 Yukon LM7 engine. I'd recommend the following on your current situation.
Verify if the donor L92 has AFM system and lifters. If it does, then you need to plug off the oil galleries underneath the solenoids of the AFM valley cover. Once you get that taken care of you'll want a stock type LS oil pump, plug the secondary oil pressure relief valve in the oil pan and either make the decision to keep VVT or not. If you do then Texas Speed has some good grind cams to get you around the 400+HP level without boost. This will in short "delete" the AFM system as they're and terrible engineering project form GM and pulling heads off to replace AFM lifter is a pain not to include the oiling issues that plague the AFM engines. If you have and delete the AFM be sure to also put a new/used driver side PCV valve cover form a non-AFM era engine. The PCV covers on later Gen III engines and some Gen IV's have a tendency to suck a lot of oil onto the intake and use about a quart or more of oil between oil changes.
If you go the route of omitting VVT then you'll need a non-VVT cam, Non-VVT Cam gear (either a single bolt of 3 bolt pattern one) and you'll need to change you CAM sensor pick-up to the appropriate cam sensor for the cam gear. This requires that you re-flash the ECU to a different file/format for that cam pick up and probably a few ECU pins need to be moved. You can find all the information for the AFM/VVT delete off of LT1Swap.com There's a very helpful link under the AFM delete section of that page. You can send them your ECU and have everything flashed and deleted to your liking.
This leads into the next step, the swap misc. items: I'd recommend deleting your post cat O2 sensors as many of us run a performance exhaust and have no need for a post cat O2 sensor since there's not one there and it reduces less codes for you to worry about. The engine mounts can be readily found off of dirtydingo.com They work great but there's multiple options in mounts. I prefer the dingo slider mounts because it allows quick adjustments when instilling the engine and trans. Run a corvette inline fuel pump with a return to the tank. The wiring harness can be re-loomed to the trucks needs in the garage but that's a fight I'm only going to fight once with this 96' Impala SS LS1 swap. All others I send out to a guy in Houston, TX. He re-wires the harness and bends it to the style of the original harness I.E. your engine harness will go up your finder down and under you brake booster and along your fire wall. Instead of the LS harness where the wiring jumps across the fender over the exhaust to the top of the intake. It looks tacky in my opinion and we can hide 90 % of the wiring along the fuel rail or behind the engine. It really gives the engine bay a professional wireless look. It ran the customer $600. I installed the harness and crimped in some E85 injectors wires for my friends swap and we threw in the donor LS1 cam from the Impala SS project. I built that LS1 engine to run a Sloppy Mechanics stage 2 cam for the sound that the customer wants. The LS1 cam works well with the trucks swap and the stock converter that came with the donor 4l60e. As for conor tansmissions we did install a corvette servo in the transmission, filter, pan gasket and flush but all other things where left as is until we either grenade that trans or feel the clutch packs slip.
For the exhaust we piddled around with the donor exhaust trying to get it to work but we decided t send it to an exhaust shop as we wanted a professional look for the truck and not that cheap welder best effort look. It'll be $400 well spent and less stressful. The final hurdles are the cooling system. We used the donor radiator and transmission cooler lines on our project. We were able to bolt everything up as you see from the original 02' Yukon and only found that the radiator shroud cover is the speed bump in that project. We're cutting out a sheet metal as a cover and painting it black to cover the radiator brackets ect. We wanted to run electric fans on the truck so we found a 2008 pick-up and pulled those e-fans. We lopped off the round upper radiator mounts at the top of the fans and mounted them onto the 02' Yukon radiator. The high speed and low speed circuits and relays where purchased from the wiring harness builder and only require you add on green wire to the ECU harness. It cost an extra $60.
Engine health: I've rebuilt/currently rebuilding many engines (LS/ GM/ FORD/BMW/ IMPORT/DOMESTIC ect) so please take my opinion as you like. IF you take that engine apart, please do yourself a favor and get a complete gasket kit, head bolts, and if your not going to machine the block please at least ball hone it and place new rings on the pistons. This is what I'd recommend at a MINIMUM. If you install a new cam, do your self a favor and spend the $34 for a set of Durabond cam bearings and install them. Run a set of PAC1218 springs if you go with a bigger cam and a set of LS7 lifters. Be sure the springs match the spring rate and seat pressure of the cam though. Now when/if you go about mic'ing the engine out: Start with the crank shaft end play and rod clearances before you disassemble that rotating assembly. It'll give you a better read on the rods-to crank clearances before you take the engine assembly apart and forget to add that factor into the overall health of the engine. If anything falls our of taper or out of round consider a complete rebuild if time and money allows it. I highly recommend any street engine that gets taken apart to be rebuilt. I.E. cross hatched for new rings or better yet bored for new pistons and ring, crank polished or ground, heads resurfaced and valves and valve seats reground. On average I spend about $500-$750 a the machine shop, $800 on a cheaper rebuild engine kit and out the door break in of around $1,500 to $1,800. That virtually a brand new factory spec LS engine completely rebuilt with appropriate bearing clearances built in.
Excuse my rant and I hope this helps. BUT if you listen to anything I say, please listen to this: DO NOT PULL THE ORIGINAL ENGINE! Keep driving her until you have everything ready. Engine is complete, wiring harness has arrived, all parts, ECU is flashed and you have all break in fluids, oils and filters at the ready. That way it's a seem-less project to swap it. In some families yard ornaments become junk yard finds or someone else's yard ornaments and that's where I hunt for my projects. Unfinished projects save me money that the original owner has spent and many times you just need to finish where they left off and many times that only about a couple thousand dollars away form making there project a dream come true for the thrifty buyer.
That is all INCREDIBLY helpful.
I’m on the fence about keeping the vvt or not. I did plan on new rings, full gasket set, and trunions a minimum “refresh”, bit had overlooked honing. I probably would have looked at the cylinder walls while doing the rings, but a hone is one of the things I'd have to buy, so I would have probably skipped it unless they were rough. I was planning on getting rid of the pcv system and going with a catch can instead. Not really going to change oil consumption, but at least it’s not going through the intake
For the fuel system, I was going to get a delco ep381 pump with the an adapters. But I really decided on that for no particular reason. Are there any benefits to either the corvette system vs a pump?
Part of me doesn’t want to dig too deep into the engine, but I think that’s because I REALLY want a 427, so if I replace much of the rotating assy, may as well do all that, which would change what I’d do with the rest of the truck.
Thanks for the tip on waiting to garage the truck till everything is READY to go in. I was probably going to start once I got the engine ready to go in, since I currently need it for school, but that’s changing soon.
So basically a Gen IV LS swap? Probably best bet is to get the entire engine/harness/tranny/TAC module/gas pedal. Check out LT1Swap.com. If you can hear an engine run, just drop it in and move on. Don't open it up and mess with it. If you want to swap the rear end, might as well get the entire vehicle as a donor. But rear end is not as easy swap from the SUVs, because those had coil spring/4 link rear suspension, and you have leafs.
A truck rear end is a better candidate. 99-02 had rear discs. 03-07 classic had drums, and I think they went back to disc again after that. Yes, I think you are correct as far as what needs to be modified to the axle. For some reason, I don't see this a lot. Seems pretty easy to me.
Good luck.
Oh, good point on the coil over vs leaf. But yes, a gen IV LS is what I’m after.
I’ve got a “working” spreadsheet with a list of what I think I’ll need w/ links that I might post once I get it more complete and get feedback on all that, but once I get it more complete
How much power could a 6l80 handle, and what's a swap like? New holes in the frame for the cross support and a custom driveshaft? I kinda like the idea of the extra gears to get better mileage, even though you don't drop in a 6.2 expecting great gas mileage.
Oh, and I really would like DBC. My dad has a G37 that's dbw and you step on it and it thinks for a second if it should let you have full chooch or not. I told you to go full throttle, go full throttle. Just do it, don't think. I believe it's a pretty simple swap, if I get one that's dbw, right?
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