Hello all! I'm pretty new to the forum here. I've done some searching but I haven't found exactly what I'm looking for yet. I've got a 1992 Buick Roadmaster estatewagon with the TBI 5.7 in it and all the options. And I've acquired a 6.0L lq4 from a 2005 Chevy 2500 with the throttle by wire and DOD. I want to start planning the swap. I want to keep all the functionality of the car but I'm hitting a hang up with the Cruse control, and trans kick-down since there is no throttle linkage to attach it to. Has anyone on here heard of someone that has done this swap? Even if not, it would be really helpful if someone could send me a good factory wiring diagram for this wagon so I can start finding and figuring what I need to make everything jive. I'll be deleting the DOD and VVT so that won't be an issue but the rest I gotta make work. Any and all help with this topic would be awesome! Thanks in advance
Firstly, you need the trans from the truck to go with the engine. Your Roadmaster has an older-style valve body that requires a throttle valve cable, whilst the truck's trans is a fully electronic trans, using shift solenoids. So if you desire to have the drive-by-wire throttle, that electronic trans is completely necessary, otherwise, you'll have to backdate the engine's setup to have a mechanical throttle body, which means an older harness that doesn't control an electronic trans.
That's how my son does them, engine, tranny, all wiring, and every nut and bolt that you can get off the donor car. Also the 2005 Chevy 2500 complete rack and pinion set up would be nice.
Oh yes that's something I forgot to say Is the engine I got is from a fella who was going to put it in an old Camaro and he already flashed the ecm to run a turbo 350 so I can't run a electronic trans even if I had one :/ i wonder what it would take to back date the engine to a throttle cable setup? I suppose I could sell this ECM and the other extra parts and use the money to get what I need... That would simplify everything actually, because I would be able to use the old Cruse control as well.
That's a good idea. I read somewhere about the stock steering box interfering with the swap. Is the rack and pinion swap something that's common on these B-bodies? I think I would like that.
I have no idea if it clears everything. When I had my UltraVan RV some owners were doing this swap. Seems like a nice rack setup.
Yes, I had big plans for it. 22'long and unibody like an airplane. Corvair set up in the rear. They actually ran fairly well and got decent mileage but not many Corvair dealerships left. With a GM truck rack and pinion and a Chevy V6 it would have been perfect. Got old, sold it cheap, and moved back to beautiful Illinois.
Since your trans is going to be a T350, you need a correctly-sized 6.0 TB (and possibly the intake) from the first years they were installed. However, the one thing I don't know, is whether all automatic-equipped LS-series engines used electronic transmissions, or if the first ones out (in the Corvette) had non-electronic transmissions. That, you will have to research.
The LS has 2 options automatic, or stick. Since you are going with an automatic, and have already had the computer tuned, you can use your 4L60. It will facilitate two things. I will give you overdrive, and the VSS will work with your speedometer. As long as you do not change rear ratios, or tire size, you can leave the VSS alone. If you change axle ratios, or tire size you will need a different driven gear, and possibly a new drive gear. The 350 may be a little weak for the LS, and the 400 is stronger, but still only a 3 speed (no overdrive). The 4L60 is an overdrive transmission. If you use a mechanical throttle pedal you should be able to get an adapter for the linkage to use the transmission, and the cruise control. The computer may have an input for the VSS signal, to facilitate cruise control with no cable or separate control box, but you would still need a cable actuator arm for the transmission. I have the specs somewhere for the cable end by the throttle valve. You need dual electric fans with the LS engine, because there is no mechanical fan that can be adapted to the engine. I suggest a 4 row radiator, especially if you are going to put a hotter cam in the engine. The hoses will be somewhat bastardized so expect to fiddle with them. I used aluminum connectors of the proper size to allow me to twist the ends of a hose to make them fit with my OCC 454 installation. You should consider a connector/bleeder for the upper hose. You need a set of adapter engine mounts. They are readily available. The engine with the FEAD will fit except for the back of the AC compressor bracket, and that can be ground to fit, for a bolt in installation. The steering will fit without modification. I would not use any rack and pinion steering unit from another car or truck, because the pivot points for the inner tie rod ends may not line up with the pivot line of the lower arm bushings. The only PS unit I know that will fit properly is: https://sweetmfg.biz/home.php?cat=22. The inner tie rod end attachment points are in the same position as the cross link, and you can use a couple extra universals to get the steering column attached to the input shaft. You still must make a bracket to bolt it to the engine cradle at the proper height, with the inner tie rod ends in line with the centerline of the lower arm pivots, both vertically and horizontally. You may be able to leave the ABS installed as well. The RM wiring is specific to 92 and 93. It also includes the 92 OCC. I teased out the wiring for the functions I wanted to keep, and whatever was left I cut, except the red and black wires. They are key on power, and can run a number of relays to operate things like fans and other neat functions. The idiot lights may or may not work properly. If they are on all of the time remove the bulb. There is a box under the dash that you can disconnect (I will have to look it up for you if you decide to disconnect it). I removed the ABS on mine because I did not have the room to keep it. The ABS on these is not really that good, and I can out-brake the ABS. You may have the programming for the vapor recovery system, and then must keep the wiring. If you need to reposition the vapor canister, you can get the bracket from a 94-96, and attach it to the frame on the right side behind the bumper cover with accompanying hose and extended wiring. The computer for the LS can then use that space for its home. The wiring that goes under the front of the LO5 will probably have the insulation fused into a lump with numerous wires running through it. The LS computer probably requires 2-4 O2 sensors. Have it programmed for the 2 in front of the cats, even if you are not running cats. Remember to hook up your heater vacuum line to the plenum, so the HVAC valves will work. The LS should have an almost autonomous wiring system, and all you need is power, ground, and sensors. I also used a separate temp sensor like the one on the left side of the LO5 (you can use the one from the LO5) for the temp gauge, just save the wire from the pass-through connector block at the firewall. Here is a thread on a forum where someone did basically what you are doing. (http://gmlongroof.4umer.com/t10158-92-olds-lsx-swap) You can join the forum, and ask him questions. I have seen his car, and it runs really good. He drove it from Connecticut to Daytona Beach FL last March for the Wagonfest. There is another one coming on Match 23-25 2018, and he will probably be there. There are details for the Wagonfest on the same forum as the thread. We expect 20-30 wagons at Daytona. I know the above is a lot to digest, and there is probably a lot more than I stated. If you have questions, you may call me at 727-692-5510. I am in Largo FL.
I added the referenced thread on the Longroof forum that I forgot to in the last post. His swap should be almost exactly the same as the OP. You can often get the factory service manual on ebay for cheap. 10~25 plus shipping.
