Gbody LS Swap Info

Zippymac

Not-quite-so-new-guy
Aug 18, 2021
41
33
18
Dripping Springs Tx
Mostly a walk through of a basic LS swap. nothing fancy - a 2002-2005 Monte Carlo or Impala has pedal that works gas pedal DBW.
I used the 2-pin alternator
ECM inside passenger area
Hooker headers with clam shell mounts H3 hummer oil pan and pickup tube relocation kit
4l65E with z-pak clutches and corvette servos
just added 3/16th angle iron to frame rails and slide the stock cross member back a bit and shorten dirve shaft.
9 inch Currie with wider track and 4 wheel disc brakes
added a lot of interior customization
Hooker truck A/C brackets with sorren A/C compressor - Original '86 A/C condensor or one out of a 2002 trans am or camaro work well too. dual fan set up from the Impala 2005.
Keyless entry / push button start
 

Zippymac

Not-quite-so-new-guy
Aug 18, 2021
41
33
18
Dripping Springs Tx
For those that hang out here and can use this, this is from my Facebook LSx GBODY page.

********THE PINNED POST.********

Putting the LS Engine in a Gbody can be done many different ways, there is no one set procedure or exact part numbers that I'm going to have here unless it's for a specific part. There are thousands of different parts out there for LS Swaps. This post is a GUIDELINE with a ton of information to help you get in the right direction and make it happen. I am not responsible for your technical abilities to be able to build a car, you need to have this knowledge on your own.

COMMON QUESTIONS THAT KEEP GETTING POSTED

RADIATOR & HOSES:

Many different Radiators will work with this swap, it doesn't need to be a fancy aftermarket one, there are factory radiators from multiple different vehicles that work for this. Any electric fan that fits on the Radiator will work and can be wired in.

For the Hoses measure out what you need and go to the store and see what fits, it's that simple. Use a coat hangar and get an idea. No set part number for "what works" because it depends on what Radiator you use.

ENGINE MOUNTS:

Many different mounts are available to mount an LS Engine into a Gbody, let alone any other car, truck, boat, airplane, and anything else. Given it's 2018 and the LS swap is pretty much the norm, every major aftermarket company has a kit of some sort. Hooker, Holley, BRP, Dirty Dingo, probably a dozen more and alot of little guys too..below is a link that is a google link showing you how to search for them. If you don't know how to use google, this will show you:


TRANSMISSIONS:

Pretty much any older GM automatic and some manual Transmissions fit in the Gbody behind the LS Engine. The 4L80E fits in the tunnel when you cut the ears off of the case, both sides. You need a 32 Spline Slip Yoke and the proper FULLY SPLINED 2wd Output Shaft for it to work correctly. The T56 6spd Manuals fit with a little tunnel work and cutting the hole for the shifter. The 6spd Auto (6L80E/6L90E) needs major tunnel work to fit. Driveshaft length depends on the setup, measure it.

TRANSMISSION MOUNTING:

The older Transmissions (TH350, TH400, 700R4, early 4L60 & 4L60E, 2004R) WILL bolt to an LS Engine, the easiest way is to use the factory GM Flexplate & Spacer from the 1999-up GM Vehicles that have the 4L80E in it. Just oval out 3 of the holes to match the Convertor bolt pattern on the older transmission. 4L80E is a direct bolt up with these parts..before anyone asks. Look in the comments of this post for further info.

TRANSMISSION CROSSMEMBER:

Many companies make these now, search for them (google). Some are direct bolt in, some are not. Think outside the box here and make it work if need be, or build your own. You are putting an engine and transmission in a car that did not come with it from the factory. Some stuff may not line up directly so troubleshoot it and see if you can make it work by possibly drilling more holes in the frame or slotting the crossmember.

DRIVESHAFT:

Depending on what mounts you use the stock one may work. Stock one is 30+ years old and not rated for the power that some of these engines make stock. If you want to run the stock one and it slings it breaking parts, that's on you. I would have a drive shaft custom made, it's not much money to get a good one and have a smooth ride. Make sure you measure correctly to get the correct driveshaft.

HEADERS:

Several companies make a set of Headers that will fit a LS swapped Gbody, search for them(google). LS Fbody Headers WILL WORK with little modification to the drivers side collector, pics in comments below.

OIL PAN:

The most commonly used Oil Pan is the GM Muscle Car Pan, also known as the H3 Oil Pan, GM Part number 19212593. People have also used the LS1 Fbody Pan, and CTSV Pan for good fitment. The Holley Swap Pan also works and works the best for clearance.

THROTTLE CABLE:

Stock factory Truck Throttle Cable works from the 1999-2003 Cable V8 Iron LS Engine trucks, before they went drive by wire. Bend the gas pedal in the car to make sure it moves the throttle body correctly. Make sure you use the proper cable stop with the plastic clip on the gas pedal side in the car.

For the DBW setups you will need the correct TAC Module, PCM, and Electronic Pedal. Some PCM's can run both, here is some info to go from DBW to DBC:


FUEL SYSTEM:

Common used is the GM Factory Gbody EFI Tanks & Sending Units, this will be from a Grand National, 1986-up Monte Carlo V6 TBI, Buick T Type, 1986-up El Camino V6 TBI for the El Caminos, or any of the aftermarket companies selling these. Rock Auto sells them. I suggest an in tank pump. Some people use external pumps on the factory tanks, you need to have a sump and plumb it correctly. Depending on what Fuel Rails you use (regulated/non-regulated) you may need to use the 1999-2004 C5 Corvette Fuel Filter/Regulator or another regulator that does the same to make the system have at least 58psi at the rails. Stock fuel lines on the Gbody WILL work, 3/8" feed, EVAP 5/16" converted to the return, and the 1/4" at the sending unit as the vent. You will need to modify the sending unit if using an in tank pump, the build threads below have information on this.

AIR CONDITIONING:

Many people have gotten the air conditioning to work quite a few different ways, with and without turbo setups.

GAUGES:

Stock Gbody Gauges will work with LS Sending Units.

Fuel gauge and Volt gauge are in the car wiring and works.

Oil pressure: hook up the Sending Unit from the Engine to the wire for the gauge in the cluster.

Tach: wire PCM Red/Green Pin 10 in the LS Engine Harness to the Tach in the Cluster, set the pulse correctly in the tune.

Water Temp: You need 1998 3-wire Temp Sensor GM Part # 12551708, wire Pin C to the Temp gauge in the cluster.

Speedometer: if using an electronic transmission, convert the speedo gauge in the cluster to electronic. Wire the VSS from Red/Green Pin 50 in the LS Engine Harness, can be calibrated correctly in the tune.

Monte Carlo SS Electric Speedo Conversion thread:


WIRING INFORMATION can be found here: http://www.lt1swap.com/wiringharness.htm

Use that page to find your harness and build what you need.

Factory GM Truck Intake and Alternator WILL FIT under the factory hood of a Gbody depending on the mounts used...there are dozens of builds on the page that show this. Search for them.

TRUCK SMALLER POWER STEERING PULLEY: DORMAN 300-201, 300-202 is the metal pulley.

Some very good LS info here:


Build threads for my 1984 SS:



T56 6spd install into a Gbody:


Those threads have plenty of information for you to research, lots of pictures and things explained.

FORD 8.8 REAR INSTALLED INTO A GBODY

You have ALL the mechanical stuff here, but its the electrical that bites most people. I was able to get things wired in and it works, but its not clean... https://lt1swap.com
One thing I would do if I had it to do all over - GM performance connect and cruise its all set up just basically bolt it in - still need fuel delivery, engine cooling, and figure out how to run the wiring. along with rear end and suspension items.
 

Built6spdMCSS

Geezer
Jun 15, 2012
5,695
9,502
113
Florida Beach
You have ALL the mechanical stuff here, but its the electrical that bites most people. I was able to get things wired in and it works, but its not clean... https://lt1swap.com
One thing I would do if I had it to do all over - GM performance connect and cruise its all set up just basically bolt it in - still need fuel delivery, engine cooling, and figure out how to run the wiring. along with rear end and suspension items.
Electrical definitely gets people, you can either do it, or you cant.

I made sure to mention that site, great info.

Capture.PNG
 
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Northernregal

Sloppy McRodbender
Oct 24, 2017
3,359
12,826
113
Red Deer, Northern Montana territory
Mostly a walk through of a basic LS swap. nothing fancy - a 2002-2005 Monte Carlo or Impala has pedal that works gas pedal DBW.
I used the 2-pin alternator
ECM inside passenger area
Hooker headers with clam shell mounts H3 hummer oil pan and pickup tube relocation kit
4l65E with z-pak clutches and corvette servos
just added 3/16th angle iron to frame rails and slide the stock cross member back a bit and shorten dirve shaft.
9 inch Currie with wider track and 4 wheel disc brakes
added a lot of interior customization
Hooker truck A/C brackets with sorren A/C compressor - Original '86 A/C condensor or one out of a 2002 trans am or camaro work well too. dual fan set up from the Impala 2005.
Keyless entry / push button start

That build isn't my cup of tea but it's pretty cool what you have integrated into the car. Is that a VW BCM for the keyless start and security? Pretty cool idea indeed. If people knew how simple the German electrical stuff was to re-purpose it would be interesting to see what they came up with.
 
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Zippymac

Not-quite-so-new-guy
Aug 18, 2021
41
33
18
Dripping Springs Tx
its based on the VW system, has the passive key - had too many Monte Carlo's stolen so got rid of the keyed ignition. without the BCM there is no power to ECM computer so no way to start the engine. if hot wired it will just turn engine over no injectors or ignition modules to run engine.
The setup was not too bad- just wire in off the switch on the column for accessory, switch power and then tie in the BCM for the locks, trunk, and ignition.
got the kit for around $150.00 - took a few afternoons mapping out against the wiring diagrams in the manual then making the proper connection preparations and a day installing it. has a wire into the horn and lights to flash lights and honk horn - can do same with a viper system too. The tesla panel was tricky because it needs a PWM for the BCM bypass since its made to fit into a 2012 La Crrosse. The panel has an ODBII input from the serial CAN BUS on the ECM trip mileage and navigation.
1. engine harness and relays current performance wiring - I used this one since the complete engine harnesses were not fully available - https://www.currentperformance.com/shop/stand-alone-fuserelay-module/ - this is more complete - https://www.currentperformance.com/product-category/stand-alone-wiring-harnesses/truck-engine/
2. body relays for doors, trunk and windows and tesla panel - this is the next level from what I have: https://www.amazon.com/dp/B011HOJRME/?tag=gbody-20
3. lights wiring set up for headlights tailghts etc...
4. A/C s run through the current performacne engine relays with input from the tesla panel is the plan still figuring that out.
5. cruise control wring is labeled just have not connected it up - basic Top brake light to TCC torque convertor lock up disconnect, cruise connector on ECM and then to the column cruise switch. basically 3 wires with an on indicator to the Dakota digital Dash input.
 
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87National

G-Body Guru
Apr 15, 2009
661
679
93
eastern SD
Im swapping my 85 cutlass Supreme brougham. going with 5.3 4l60e. Will need to change the original shifter to work with the 60E? its my first swap go easy please lol
Floor or column shifter?

I swapped a 4.8/4l60e into my 86 442 and retained the factory floor shifter. Here is how I did it:

I used a B&M shift lever:
https://www.speedwaymotors.com/B-M-...oAVeD8dN8uS1GqNJo_KEYkIA-WrD-nHoaAtRKEALw_wcB

......an fbody 700r4 shift cable and an fbody 700r4 trans bracket:

You have to modify where the cable snaps into the gbody shifter (it will be a few inches forward of where the 200r4 cable attaches). I don't have pictures of my setup......but I did something similar to the attached link:
https://gbodyforum.com/threads/shift-cable-for-4l60e-swap.52071/
 

Jaybo78

n00b
Apr 5, 2022
3
2
3
5.3 drive by cable, stage2 cam, headers, mated to th400 in an 81' Monte Carlo. I have stock harness and ecu. Will mega/microsquirt work with swap/cut down harness? Any extra tuning required? First Ls swap, so I'm trying to do my homework. Thanks
 

Wraith

Royal Smart Person
Jan 13, 2013
1,599
4,747
113
DFW, TX

64nailhead

Goat Herder
Dec 1, 2014
5,659
1
12,059
113
Upstate NY
Yes a Mega/Microsquirt will work. And there will most definitely be tuning required. But there is tuning required for all swaps regardless ECU brand.
 
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