LS Swap Guide by LSX Innovations

INTRODUCTION

This guide will assist you in making a seamless LS engine swap. Since every LS engine swap is a little different and there are lot of choices to be made, you can use this guide as a reference for ideas and part numbers as you move through the process. You will find options and recommendations for motors and motor mounts, transmissions and flex plates, accessory drives, wiring and computer systems, oil pans, steam tubes, gauges, fuel systems, exhaust systems and carb conversions. We hope that this guide will make your LS swap as simple as possible.

Disclaimer: This guide is intended for informational purposes only. You will need to verify everything for your own specific needs and the vehicle being worked on. The information here is for general application. With that in mind, there is no guarantee of fit and/or function for a specific vehicle.

MOTORS AND MOTOR MOUNTS

An “LS swap” is an engine switch and installation. The “LS” can mean any engine made by GM from a factory truck 4.8 to GM’s popular LS3 or LS7. The specific LS engine you choose to start with will depend mostly on the budget you have to work with.

Choosing an engine all comes down to what your particular goals are in making an LS swap and how much you want to spend.

JUNK YARD

For most, a junk yard 5.3 or 6.0 is the target engine to swap if you aren’t concerned with having an all-aluminum block. They can usually be had from $500-$1,500 depending on displacement and mileage. They are cheap, readily available in any junk yard, and you can make decent power with just a cam swap.

ALL-ALUMINUM LS1 ENGINES

The next step up in price is the all aluminum LS1 engine. This LS engine was first released in the 1997 Corvette, and is still a popular option because of the design which makes it small, durable and light. Complete with all accessories, this engine will typically run close to $2500.

The LS3 and LS7 engine models from GM are the next step up. The LS3 was first released in the 2008 Corvette and was the most powerful Corvette engine to date. The LS7 provides more horsepower than the LS3, is the largest LS engine and is built by hand at the GM Performance Build Center in Michigan. The LS3 and LS7 engines run anywhere between $7000 and $12000.

MOTOR MOUNTS

The motor mount adapter plates are the foundation to a successful LS swap. Adapter plates bolt onto the LS engine block, allowing you to bolt the engine securely to the crossmember. There are adjustable and stock location adapter plates available (also known as 1-inch setback plates). Stock location refers to the point where the transmission meets the engine.

When mounting the engine, keep in mind that the mating point for an LS engine has a different distance from the transmission than the mating point for a SBC engine. Most car applications require the LS engine to be moved forward due to firewall clearance issues with the passenger side cylinder head.

For more details about LS engine sizes and codes, look here.  

At LSX Innovations, we offer adapter plates for both of these applications.

We offer adapter plates for both of these applications.

LOW MOUNT AC COMPRESSORS

What if you want to keep your factory low-mount AC compressor? Is this possible?

The answer: Yes. You can keep your factory low mount AC compressor. However, no adapter plates on the market will fit properly. To use the factory low-mount AC compressor you will have to notch the crossmember frame to make it fit.

This is because the LS AC compressor and bracket hang directly in the way of your factory crossmember. This is the case on all GM car applications.

Notching the crossmember will require a welder and a cut-off wheel.

TRANSMISSIONS

After choosing which LS engine you will be using for the LS engine swap, you need to pick which transmission you want to run behind it.

Some people like to use the older GM TH350, TH400 or 700R4 transmissions. These are economically adequate choices. However, these transmissions require a flexplate adapter to work with the LS series flexplate. We offer this adapter in our carb conversion section of our store. Check out the flexplate section below for more information on this.

AUTOMATIC TRANS

We highly recommend the GM 4L60E transmission over a traditional 3 speed automatic. The 4L60E transmission provides an ideal driving experience to match the price point.

The 4L80E and 6L80E GM transmissions are fantastic choices as well if your budget allows. Usually they are not needed unless you have a built engine.

All three of these GM transmissions can be sourced easily from a local junkyard.

MANUAL TRANS

For those of you who want to bang through the gears for an exciting driving experience, we recommend the T56 or TR6060 transmissions. With the correct flywheel and clutch (sourced from the donor vehicle of your transmission), either of these transmissions can easily bolt up to any LS engine you are using.

Other popular options are the TKO500 and TKO600 transmissions. Many carbureted cars have already been converted to these modern 5-speed transmissions, however the input shaft isn’t long enough to reach the crank. To get around this, just swap the old bellhousing out for the GM 621 bellhousing. To do this you will also need a pilot bushing (GM Part Number: 12557583 or its equivalent) and an LS flywheel (Part Number: 12561680 or its equivalent). This particular flywheel is .400 inches thicker than the standard LS flywheel, which makes up for the difference of the LS crank being .400 inches further behind the bellhousing.

Adapter brackets are available from Street and Performance and Detroit Speed for mounting the hydraulic master cylinder to the firewall behind the brake booster. Or, with a drill press and some simple tools, you can always check out YouTube, get adventurous and make your own.

There are a lot of different ways to go about setting up your hydraulic clutch system, but some examples below will get you started in the right direction:

Hydraulic master cylinder adapter bracket

Or complete kit with master cylinder: Mcleod part number 1434002

FLEX PLATES

Flex plates may or may not be a concern when making your LS swap. If you are using a modern transmission (4L60e, 4L80e 6L80e or newer) there won’t be a problem. You can simply use an LS flexplate.

If you are trying to mate an older transmission, such as the TH350 or TH400, etc., then you can still use the LS flexplate, but you will need a flexplate spacer to make it work. We offer this spacer in the carb conversion section of our store.

The flexplate spacer will work to provide support for your torque converter hub, and align it with the crank.

ACCESSORY DRIVE

The accessory drive propels the accessories that work in tandem with the engine.

There is no “one size fits all” when choosing an accessory drive to use in your LS swap. You will need to do some additional research about your specific LS swap application with your specific needs and what will fit in mind.

Below is some basic information to get you started:

There are three basic accessory drive spacing layouts. Corvette, Camaro, and Truck/2010+Camaro spacings.

The Corvette spacing is closest to the engine block, while the Camaro spacing is 3/4 inch farther away. The Truck/2010+ Camaro is 1.5 further away than the Corvette spacing.

We offer a variety of accessories drives to get your LS swap going. Check out our LS brackets section to see them all.

A variety of companies sell factory and aftermarket solutions to these accessory drives. There is no “1 size fits all”, you will need to research your specific swap application to determine what system will work best for you.

WIRING & COMPUTERS

The engine wiring harness is an important component of your LS swap. It can be intimidating to some, but it really is pretty straightforward and simple.

When doing an LS swap, you have three options in integrating the engine wiring harness successfully. You can buy a stand-alone harness, have a new harness custom built or rewire the harness that came with your LS engine.

In most cases, people end up having the harness that came with their LS engine rewired. This option is cost effective and can be done easily by a professional who has experience with these harnesses.

Though doing the wiring for the harness yourself might be tempting as it can save money, we strongly recommend having the rewire service done by a professional, unless you already have experience in proper wiring techniques.

If you are still determined to tackle this task on your own be sure to do your homework. You can find some helpful videos on YouTube to help get you through the process.

Easy EFI Solutions is a great company to work with when working on your engine wiring harness. One desirable service they offer is in taking out all of the unnecessary wiring from your current harness and converting it into a three-wire hookup for the power lead, fuel pump lead and ignition lead. They also provide drop-in engine packages and PCM flashing to help you get your project going.

OIL PANS

The oil pan seals off the bottom side of the engine and houses oil that is not currently being moved through the engine as lubrication.

Because the clearance beneath is different for cars and trucks, different oil pan applications are required.

CAR APPLICATIONS

For car applications, there are many options out there, but at LSX Innovations there is only one we prefer. We highly recommend going with Holley’s 302-2 oil pan. We prefer this oil pan because we have yet to find a classic Chevy car application that it won’t work with. The Holley 302-2 oil pan runs around $350, and is well worth the investment. In our experience, other oil pans tend to be hit or miss in quality and fitment.

TRUCK APPLICATIONS

Truck oil pans are a bit easier, as most stock truck oil pans typically fit well into classic truck applications. They do however, tend to hang a little lower than the factory SBC pan, but this can be worked around. If you are looking for a specific recommendation, we prefer the Hummer H3 oil pan, as in our experience it works well on all truck applications.

STEAM TUBES

Steam tubes are the tubes at the top of the heads in the engine. They keep the heads from overheating by allowing hot spots to clear and escape. They are essential, so do not cap them off unless you have completely bled off all the air in the coolant system. Capping them off will cause problems down the road, creating hot spots around the top of cylinder 1 and cylinder 2 if there is any air left in the system.

When doing your LS swap, you want to make sure that the tubes connect somewhere that the air can escape safely. Some people connect the steam tubes to the water pump spacers or the water pump housing and some connect them to the radiator.

We offer a variety of fittings to assist in your steam tube routing.

WATER PUMP SPACERS AND HOUSING

If you are using water pump spacers you can run your line right into them. Another option is to drill into the top of your water pump housing, fit a 1/8 barb fitting inside and connect it there.

RADIATOR

You can run a line into the top radiator hose, or you can drill into the high point in the radiator and connect there.

YOU CAN FIND A LOT OF TIPS AND TRICKS ON HOW TO DO THIS PROPERLY ON YOUTUBE.

GAUGES

Your gauges provide you with valuable information about what is happening inside the car, so when doing an LS swap you want to choose carefully and install them correctly.

MECHANICAL GUAGES

The temperature gauge mechanical senders can be installed directly into the LS engine block with an adapter fittings from LSX Innovations. The adapter fitting is inserted right into the LS engine head. We have a bunch of different styles of adapters to all gauge probe types.

Visit our store for your mechanical oil pressure or oil temp gauges.

If you are using an older transmission you can use a factory speedometer. If your transmission is modern, then you will need a gear housing that will accept a mechanical speedometer. Advanced Adapters is a company that makes a great gear housing.

Another option when ensuring speedometer compatibility is to use a Cable X  to run a mechanical speedometer cable to the transmission. The Cable X will convert your transmission Vehicle Speed Sensor (VSS) to drive the cable correctly.

ELECTRONIC

If you want new electronic gauges, there are several aftermarket manufacturers, such as Auto Meter, VDO and Dakota Digital, that make electronic gauges and senders. These electronic gauges and senders can be wired into your LS wiring harness.

FUEL SYSTEM

For the fuel system when doing an LS swap, the most common approach is to use a C5 Corvette fuel pressure regulator along with an electric fuel pump that has adequate flow, such as the Walbro 255. People also typically use Russel fitting adapters with this combo.

If you don’t already have a fuel injection rated fuel line, you will need that as well. In a fuel inject setup the system needs consistent pressure to operate.

If there is no baffle in your tank and the fuel moves away from the pickup tube when you are cornering, your engine will die. However, this is typically only an issue if you run your tank below ¼ full.

External pumps do work, but an intake pump with proper baffling is recommended to avoid fuel starvation when you reach low gas tank levels while cornering. This is not an issue with a carburetor, as the bowls have enough in them to keep the engine from running out.

To sum things up, if you don’t plan on using a baffled tank, then we recommend not letting the tank get below ¼ full to keep your engine from dying.

LS1 Tech is a good source to find fuel system setup diagrams and part numbers that you will need.

EXHAUST SYSTEM

The combinations and options are never-ending when it comes to exhaust systems. From the get go, you should expect that no exhaust system is going to fit right out of the box. At the very least, you will need to have your factory pipes lengthened or shorted, depending on the car’s current exhaust system.

Are you going to use headers or stick with factory LS manifolds?

Switching to headers will help you gain top-end horsepower, while keeping your factory LS manifolds will retain low-end torque.

Headers do a great job of waking up an LS engine and they also sound great. Since this has become a popular swap, many big header manufacturers make swap headers. Doug Thorley and Hooker both offer LS swap headers that work with a variety of applications.

If you want to keep things quiet and you are not concerned with squeezing out all of the horsepower you can get, then the factory manifolds are a good option. Most factory manifolds will fit any application.

CARB CONVERSION

If you have decided to use a carbureted setup, you will need a carburetor LS intake manifold. There are a lot of options available. Edelbrock and Holley both provide a variety of options.

If you are switching to a carb, you can delete the unnecessary knock sensors and wiring that sit in the valley cover. LSX Innovations has a carburetor conversion valley cover to help you easily delete these sensors. The LSX valley covers are lighter than factory units and they look much better as well.

Since there is no provision for a distributor, you will need a control box to run the ignition system on an LS engine. We recommend checking out the control box made by MSD.

LSX Valley Covers are lighter than factory units, and look much better too.

REVIEW

LS swaps will save you a lot of money over the long run in fuel mileage. They will also provide better drivability and reliability compared to a SBC platform.

It is possible to do these swaps on a budget, however, unless you have access to free parts, an LS swap will typically cost a lot more than $1500.

We hope you have found this LS swap guide helpful. Please feel free to send us any comments or suggestions you may have.

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