Gbody LS Swap Info

Built6spdMCSS

Master Mechanic
Jun 15, 2012
305
63
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

 
Last edited:
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JAMCAR223

Royal Smart Person
Jun 6, 2014
1,722
113
Houston, TX.
Good info right there! I saved it for future use. Thanks for posting.
 
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Reactions: 1 user

Built6spdMCSS

Master Mechanic
Thread starter
Jun 15, 2012
305
63
Flexplate diagram I mentioned, bolting up a older style SBC Automatic Transmission behind an LS Engine. 4L60E or 4L80E Flexplates, need the longer 4L80E bolts for both.

FLEXPLATE%20SPACERS_zpsicy5j730.jpg
 

81cutlass

Comic Book Super Hero
Feb 16, 2009
3,519
113
Western MN
Lower radiator hose out of a 88 f150 I6 300 van works perfect.

Upper, stock 99+ chev 1500, 2500 whatever works great but is ugly.
 

Built6spdMCSS

Master Mechanic
Thread starter
Jun 15, 2012
305
63
I used LS1 Fbody upper and fit the lower, there are a bunch that will work, just depends on the Radiator.
 

Rollingmullet82

Not-quite-so-new-guy
Feb 28, 2017
23
3
This might be a dumb question but I was going to order my engine mount adapters today but most of what I've seen specifically says for original sbc cars. Is there a difference in the mounts I need for my car it's originally a 3.8 car ?
 

Regalman08

Apprentice
Oct 19, 2015
73
33
Canada
This might be a dumb question but I was going to order my engine mount adapters today but most of what I've seen specifically says for original sbc cars. Is there a difference in the mounts I need for my car it's originally a 3.8 car ?

You can use all the stock small block Chevy mounting hardware as if you had a small block to start with but you will have to move the clamshells that are mounted to the frame forward and you will use only three of the mounting holes just like the V8 cars
Some of the V-6 cars did not have the third hole drilled in the frame where the clamshell would mount on a small block car so you may have to drill one more hole
 

Rollingmullet82

Not-quite-so-new-guy
Feb 28, 2017
23
3
You can use all the stock small block Chevy mounting hardware as if you had a small block to start with but you will have to move the clamshells that are mounted to the frame forward and you will use only three of the mounting holes just like the V8 cars
Some of the V-6 cars did not have the third hole drilled in the frame where the clamshell would mount on a small block car so you may have to drill one more hole
Thank you just wanted to be sure my buddy says he used these but I'm not sure if I want to use them
Camino-C10-SBC-/401263368951?nav=SEARCH
 
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