LS swapping the 1978-87 GM G-Body and A-Body (photos)
These last of the rear-wheel drive intermediates were distant cousins to the muscle cars of the 1960s, but in most cases lacked the muscle. Swapping an LS motor into a Monte Carlo, Cutlass, Grand Prix, Regal, or El Camino is an easy fix for that.
1. Last of the Real Muscle Cars?
Although the A-body/G-body cars were mid-size vehicles produced with the classic body on frame, front-engine/rear-wheel drive layout, new vehicle fuel standards and emissions regulations took a major toll on their power. Even the fire breathing Buick Grand National only had 245 hp and 355 lb-ft of torque, and that was the fastest of the bunch. The A/G platform was the backbone of GM during the late 70's and through the 80's, thus there are plenty of cars out there just waiting for performance upgrades. These cars are still popular platforms for performance enthusiasts, featuring a modern chassis and brakes, fairly light weight, and a size that fits into modern traffic. It is no wonder why the A/G-body cars, not to mention the El Camino and GMC Caballeros trucks, are the perfect foundation for a hot-rod LS build.
2. Engine & Transmission Mounts
Properly placing an LS-based engine and your choice of transmission into a G-body chassis is the first step of the conversion process. With the popularity of LS swaps at an all time high, companies such as BRP Hot Rods and Holley Performance are offering complete kits to transplant them, including engine mount plates and transmission mounts/crossmember. If you're are budget minded, individual components can be pieced together to save a few bucks. Companies such as UMI Performance, Hedman Perfomance Group, and Spohn Performance produce quality engine mounts plates that bolt directly to the frame to ensure proper driveline angles. Similarly places like G Force Performance and Speedtech Performance sell transmission crossmembers to accommodate just about any transmission, though many have reported that the stock crossmember can be used by drilling new holes in the frame rails. Whichever mounts you use, be sure to install a proper high clearance oil pan that will not interfere with the crossmember or hang below it. Holley makes a good retrofit pan that fits most cars.
3. Exhaust & Accessory Drive
There are numerous exhaust options when performing an LS swap in the G-Body. Any of the stock exhaust manifolds (except LS truck manifolds) as found on the Corvette, CTS-V, GTO, and even F-body cars will easily fit and provide plenty of clearance. For a bit more panache and performance, consider one of the many header options provided by Hooker and BRP Hot Rods. Hooker takes things a step further by offering both a 2.5" and 3" complete exhaust system designed specifically for an LS swapped G-body.
The accessory drive setup has caused a number of headaches during LS engine installations, but the G-body platform is straightforward. A stock truck accessory drive setup will clear the hood on the G-body, but will require slight notching of the passenger frame rail for the AC compressor as well as a smaller power-steering pump pulley. The F-body drive setup gives additional hood clearance, but will also require minor notching of the passenger frame rail. For those wanting a setup that will fit right out of the box, consider the offerings from Concept One and Billet Specialties that eliminate the AC clearance issues by moving the compressor.
4. Fueling & Cooling
The fuel system components for an LS conversion will vary depending on if it is going to be running a carbureted setup or the stock fuel-injection system. Edelbrock sells a complete kit, sans a carburetor, for the carb conversion, but many agree it can be pieced together for less money if buying components individually. Then you can reuse the factory tank, and plumbing, though you have to add a low pressure electric fuel pump. An EFI setup requires plumbing a return fuel line, and a high pressure electric pump. Fortunately, BRP Hot Rods and G Body Parts offers several options to simplify the conversion, like the BRP in-tank retrofit fuel pump that utilizes the stock fuel tank. Additionally, both companies offer complete fuel tanks with accompanying in-tank fuel pumps for your particular LS engine output.
Depending on the power output level of your LS engine, the stock radiator may be adequate for your needs. A number of individuals have reported that the stock G-body radiator can be used by simply being creative with the coolant hose routing and fan. For those who either plan on making tons of power or are simply in need of a new radiator, drop-in radiator units specifically designed for a G-body LS swap are available from places such as RnD Fabrication and Griffin Thermal Products.
5. Wiring & ECM
As previously mentioned, using a carburetor can eliminate additional wiring harness and ECM hassles. A stand alone ignition box operates the ignition coils, like MSD's 6010 or 6012 box (depending on reluctor wheel tooth count) which simply connects to the coils, camshaft, crankshaft, and MAP sensors with an included harness to quickly get you up and running.
Injected applications are a bit more involved as they will require the installation of an ECM and appropriate wiring harness to tie everything together. Fortunately there are a number of companies such as BP Automotive, LSX4U, Hot Rod Harness, and PSI who offer standalone systems, custom wiring harnesses and ECM kits that are plug-n-play. Custom wiring solutions allow owners to configure a harness and ECM tune specific to their application. On the other hand, individuals have created their own wiring harnesses at a fraction of the cost. If you start your swap with a running donor vehicle, and use DIY instructions that are readily available from internet sources, it really isn't all that much work.
For help with service and maintenance of your car, check out the how to section of LS1Tech.com