12-Valve Cummins Swap: Everything You Need To Get It Done

There are several reasons why someone might want to do a 12-valve Cummins swap in their truck. First and foremost, the 12-valve Cummins diesel engine is renowned for its reliability and longevity, making it a popular choice for those who need a truck that can handle heavy loads and/or long hours of operation. Additionally, the 12-valve engine is known for its simplicity and ease of maintenance, making it a favorite among DIY mechanics and truck enthusiasts.

Another reason why someone might choose to 12-valve Cummins swap their truck is to increase its power and torque output. The 12-valve Cummins engine is capable of producing impressive amounts of both, making it a popular choice for those who want to upgrade their truck’s performance capabilities.

cummins swap

But how do you start? Where do you go to get parts? Well, to complete a 12-valve swap in a truck, you will need to source several parts, including the engine, transmission, wiring harness, and various ancillary components. A swap like this can be done with professional results or if you are so inclined, a “good enough” finish that simply gets you running. That, though, is completely up to you. Depending on how much money you want to spend and the time you want to impart into the project.

Where Do I Go?

  • Many salvage yards specialize in diesel trucks and probably have a 12-valve Cummins engine or other parts you need in stock.
  • Online marketplaces such as eBay, Craigslist, and Facebook can be good sources for used parts.
  • There are many specialty suppliers that offer 12-valve swap kits and other components specifically designed for this type of project.
  • Cummins is a well-known diesel engine manufacturer, and their authorized dealers may be able to help you source the parts you need.
  • Online forums, Facebook groups, and local diesel truck clubs can be great places to connect with other enthusiasts who may be able to help you locate the parts you need.

Cummins swap

It’s important to note that a 12-valve swap might not be the best choice for everyone. Depending on the specific vehicle and driving needs, there may be other engine options that are better suited to your needs. Additionally, swapping an engine can be a complex and expensive process, so it’s important to carefully consider all the factors before making a decision. However, if you’re here and you’re still wondering, the rest is for you.

12 valve Cummins Swap: What Do I Need?

First and foremost, you are going to need to source an engine. This is the heart of your swap and you need to find a mechanically sound unit. As mentioned, you can find one of these almost anywhere. Next, depending on the year and model of your truck, you may need to source a compatible transmission to mate with the 12-valve engine. Two of the more common transmissions used in these swaps are the Dodge NV4500 or the 48RE.

If swappers are craving a 4R100 transmission, Destroked offers a 12-valve and 24-valve Cummins to 4R100 adapter plate that would allow that to happen. For those who are deadset on the Allison-Cummins conversion being the best-of-the-best, CA Conversions makes a complete kit to bolt a five or six-speed Allison transmission that includes a flexplate and adapter plate. This is compatible with any of the Cummins engines, 12-valves included.

It is a rarity that you transplant an engine into an engine bay and it bolts right up. With a 12-valve, it really depends on what the donor vehicle is. Over at Diesel Conversion Specialists, they offer pre-made mounts for a 1967 to 2010 Ford, 1973 to 1999 Chevrolet, and more. Or, if you’ve got a friend who can fabricate, you could modify a set of factory mounts to close the gap between the engine and frame rails.

With the engine in, the wiring will be a vital next step. You will need to acquire a wiring harness that is compatible with the engine and truck. This can either be a handmade harness or a pre-made harness. The harness can be sourced from the engine you bought, a salvageable one from a local junkyard, or a pre-made harness meant for swaps from shops like Gray’s Performance & Off-Road.

Depending on how you’re planning on venting this engine into the atmosphere, you’ll need to source an exhaust system. Again, this all depends on what your plans are for the build. While a prevent exhaust might not be an option, you can purchase some kits and even sections of tubing to create a custom exhaust from Flo~Pro Performance Exhaust.

More than likely, the factory cooling system, alternator, power steering, and air conditioning that is existing will not work for this engine. You will need to outfit the truck (or vehicle) with parts that are compatible and will safely make this engine perform. There are many companies that offer parts for 12-valve engine swaps, and the specific parts you need will depend on your vehicle and the swap you’re planning. Here are a few companies that offer a wide range of parts for a 12-valve Cummins swap.

Industrial Injection of Salt Lake City, Utah offers a wide variety of parts for 12-valve engines. You can lean on them for parts like a P7100 injection pump, pump parts, and even engine upgrades. For example, depending on what you want out of this engine swap, Industrial Injection offers a remanufactured P7100 injection pump, a 12mm Dragon Fly pump, and even a high-horsepower 13mm Dragon Flow pump capable of 1,000-horsepower+.

PureFlow AirDog would be an excellent resource to use when it comes to a reliable fuel system. The AirDog 4G FP-150 GPH is the original proven Air/Fuel Separation Cummins lift pump or Fuel Preporator. A lift pump system is a must-have for your 1994-1998 12-valve Cummins diesel. The fuel system on a Cummins diesel truck is the heart of the vehicle’s performance and reliability. This low-pressure Cummins lift pump mounts to the inner frame rail using the supplied sandwich plate mounting system. Lines and fittings are included to connect the injection pump return, which would normally recirculate through the factory fuel filter housing, to the injector return line and is returned to the tank.

If you mention mechanical diesel power, Scheid Diesel will enter the conversation every time. You can rely on Scheid when you’re looking to upgrade to larger delivery valves, injection pump lines, and even larger fuel injectors. With the listed items above, you should have everything you need necessary to repower your vehicle with the 12-valve Cummins engine.

It’s important to do your research and find a reputable company that offers high-quality parts and good customer service. You may also want to consult with the professionals when upgrading because they’ve got the experience to know what recipes work best for the end goal you’re looking to achieve.

For more information about these companies, be sure and check out their websites and social media pages. Stay tuned to Diesel Army for more industry news, event coverage, and truck features.


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About the author

Artie Maupin

Artie Maupin is from Southeast Missouri and has an extreme passion for anything diesel. He loves drag racing of all kinds, as well as sled pulling competitions.
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