Jeep Wrangler driving off-road with a 4BT Cummins engine
Call us

Cummins 855 Engines

Replacement Cummins 855 Big Cam Engines For Sale

We offer a couple of different solutions when it comes to the legendary Cummins 855 Big Cam: long block and remanufactured extended long block options. All of our Cummins 855 Big Cam engines are built back to OEM specs or offered as direct replacements, complete with new castings. 855 Big Cam engines are primarily suited for industrial and agricultural applications, but can also be used in over the road truck applications. Usually, long blocks are better options due to their ability to be retrofitted with an existing fuel system governed for on-highway use (i.e. variable rpm).

Cummins 855 Big Cam Long Block

855 Big Cam Long BlockLong blocks are a good option for both on-highway and off-highway industrial use. At Big Bear Engine Company, our long block 855 option (50-percent to 75-percent assembly) is a suitable replacement for an existing engine that has experienced catastrophic failure but that still has ancillary components in good working order. That means if you spun a bearing, threw a rod through the block or dropped a valve, our long block is a more cost effective alternative than a complete engine. Ensure that the turbo, fuel pump, manifold, fuel lines and accessory drive components are undamaged before looking at a long block option. Metal shavings and lack of oil pressure can oftentimes leave unseen damage behind. Cummins 855 NTC, NTA, NT and NH versions can be built to spec either as an extended long block or long block option to an ESN and CPL Number. Check with your sales representative for lead time and availability for custom engine orders.

Long block castings are new replacement assemblies. A long block includes:

  • Block
  • Cylinder Head
  • Camshaft
  • Followers/Lifters
  • Pistons
  • Gaskets and Bearings
  • Piston Rings
  • Plugs and Bolts
  • Pushrods
  • Thermostat
  • Connecting Rods
  • Front Cover
  • Timed Front Gear Group
  • Crankshaft
  • Oil Pump
  • Water Pump
  • Oil Cooler
  • Freeze Plugs
  • Oil pickup tube
  • Oil Pan
  • Standard 6 Months Parts Replacement Warranty
  • 1 or 2 Year Extended Warranty Available


Cummins 855 Big Cam Remanufactured Engines:

Cummins NTC 855 Big CamOur Cummins 855 reman engines are regarded as "extended long blocks," which are effectively whole engine assemblies. The Cummins 855 Big Cam complete engine is considered a more complete option for re-powers where an old, worn out assembly is being replaced. We offer Cummins 855 Big Cam III and Cummins 855 Big Cam IV options up to 400 hp, depending on fit and application. These engines have gone through a complete overhaul process at our facility and have been remanufactured with roughly 90-percent new Cummins parts and 10-percent aftermarket components. The remanufactured NT 855 engine comes with a new block, PTG Pump, pistons, piston rings and bearings, liners, camshaft, turbo, valves, rocker arms and more. The majority of its parts are brand new, especially critical wear parts. In most cases, the cylinder head and injectors are remanufactured, as is the block (if required). Remanufacturing means to bring an engine back to OEM spec, which is not the same as a lesser "refurbishing" or even "rebuilt" classification. Remanufactured engines are "like brand new" and configured to exact tolerances. The engine does not include the starter, alternator, flywheel or flywheel housing, as those components are typically retained from the old engine. A build sheet and run test video can be provided upon request.


NTC 855 Extended Long Block Engine Includes:

  • Block (3081283)
  • Cylinder Head (4915442)
  • Camshaft and Lifters (3253960)
  • Pistons, Rings, Bearings
  • Rocker Assemblies
  • Injectors (3047991)
  • Connecting Rods
  • Crankshaft
  • PTG Fuel Pump (3021966 -With Additional VS Throttle)
  • Turbocharger (3048808)
  • Vibration Damper
  • Water Pump
  • Oil Pump
  • Oil Cooler
  • Accessory Pulley
  • Air Crossover Tubes
  • Starter (Not Included on Standard Builds)
  • Alternator (Not Included on Standard Builds)
  • Flywheel (Not Included on Standard Builds)
  • Flywheel Housing (Not Included on Standard Builds)
  • Oil Pan and Pickup Tube
  • No Core Charge
  • Comes with 12 Months Parts Replacement Warranty
  • 1 or 2 Year Extended Warranty Available

NTC 855 Engine Specs:

  • Model: NTA855-C400
  • HP: 400 hp @1,800 rpm
  • CPL: 3554
  • Fuel Pump: 3021966


Cummins 855 Big Cam History and Specs

Cummins NT855 Big Cam EngineWe here at Big Bear Engine Company are proud to be able to offer replacement options for the Cummins 855 Big Cam engine. The 855 Big Cam (coined “Big Cam” due to its larger-than-conventional, 2.5-inch camshaft diameter) replaced the Small Cam 855 of the 1960s and was the first engine designed to meet the emissions regulations mandated in the Clean Air Act of 1976. The 855 Big Cam is regarded as one of the last true variable timing mechanical engines on the heavy-duty side of the trucking industry, before electronics came into play with the N-14. The engine was first introduced in 1976 and mass produced up until 1985. Then following its high production days, the engine was still supplied by Cummins up until 2000, with significant engineering supersessions occurring between 1988-1991.

Owning The Class 8 Segment

The 855 Big Cam was the driving reason behind Cummins’ share of the over the road engine market growing from 29-percent in 1975 to 63-percent by 1983. It enjoyed tremendous reliability, was powerful and—thanks to peak torque being produced at very low-rpm—yielded best-in-class fuel efficiency. No wonder why old school truckers and farmers loved the Cummins 855 Big Cam. The over the road truck application is designed to run for 700,000 miles before a major overhaul becomes a consideration.  Outside of tractor trailers, the Cummins Big Cam 855 can be found in combines, tractors, harvesters, swathers, seeders, balers, excavators, dozers, compactors, rollers, pavers, loaders, large skid steers and track loaders, industrial forklifts, motor graders, cranes, dump trucks and more.

Demand Flow Cooling System And Big HP Fueling

Notable aspects of the 855 Big Cam design is its demand flow cooling system. Highly innovative for its day, the demand flow cooling system only cools parts of the engine when cooling is needed. This saves energy, allowing more horsepower to be used for the task at hand. The additional horsepower is also what made the 855 Big Cam so popular over the previous, small cam models. Its bigger camshaft diameter and larger, top-stop injectors improved the performance of these engines substantially. Top-Stop Injectors are all mechanical but are designed to use a zero lash setting on the base circle of the cam injector lobe. This zero lash setting became known as the Inner Base Circle or “IBC,” and it increased fuel flow significantly over small cam models.

Durability And Horsepower Go Hand-In-Hand

Thanks to the Cummins 855 Big Cam, producing 400 hp (or more) is attainable, but it can also be made reliably and without having to perform any upgrades on the fuel pump. The one drawback to the 855 Big Cam’s fuel injection system is the lower 2,200 psi it operates at. The relatively low injection pressure negatively affects power to the oil pump, water pump, variable timing system and valve spring pressures. In cold climates, the engine can be difficult to start. However, this can be solved with the use of block heaters or oil immersion heaters. Despite the hard starting when cold issue, you’re not likely to have a whole lot of issues with this legendary diesel engine.

Cummins 855 Specs

Engine Data

Engine TypeFour Stroke, Six Cylinder, Inline
Displacement856 ci (14.0 L)
Bore5.50 in
Stroke5.98 in
Compression Ratio10:1
Max Horsepower605 HP @ 1800 RPM
Max Torque Ratio1,118 ft-lbs @1800 RPM
Governed Speed1800 RPM
Cylinders6 Inline
Cylinder Head MaterialCast Iron
Engine Block MaterialCast Iron, Removable Liners
Camshaft DriveGear Driven
CrankshaftForged Steel
Fuel SystemPT Self Adjusting System, Direct Injection
Starting System24 Volt, negative ground
Emission AbatementEarly Versions N/A, Later Tier II, Tier III
TurboHolset or Aftermarket
Oil SystemWet Sump
Oil System Capacity38.6
Cooling Capacity45.0 L
Cooling SystemWater-Cooled
Control SystemMechanical
Dry Weight3,150 lbs.


Give us a call today at 844-340-4114 for immediate sales and support for our Cummins Big Cam Engines for sale, Cummins 4BT, Cummins 6BT, 6CT, ISC, 855, QSB 4.5 L or CAT 3306. If you have any questions check out our FAQ Page. We are always ready to help or just listen to your crazy off-roading adventures!

Request A Quote

Cummins 855 Engines Gallery

855 Big Cam Long Block 1
855 Big Cam Long Block 2
NT855 1
NT855 2
NT855 Engine Assy  1
NT855 Engine Assy  2
NT855 Engine Assy  3
NT855 Engine Assy  4

Request a Quote

Please fill out the form below with your information and request. A member of our staff will be with you shortly.


Got an Engine Down?

Discover your best options!
Get our FREE 8-Page Diesel Engine Replacement Guide

    I am looking for an