Description

The Cummins 855 Big Cam was the company’s last mass-produced real mechanical variable-timing engine in 1976. The Big Cam engine, which replaced the small cam 855, was Cummins’ first to comply with the Clean Air Act and noise regulations of the time. The Cummins Big Cam 855 engine was built in four generations and was replaced by the N14 in 1985. The 855 Big Cam is a favorite of ours because of its raw horsepower and dependability. A Cummins 855 Big Cam will comfortably run 700,000 miles before needing to be overhauled. The Cummins 855 Big Cam was the company’s first engine to use demand-flow cooling, which cools the engine only when it requires it. The saved horsepower at the crankshaft is then used to put more horsepower into the project at hand.

By incorporating pulse manifolds into the engines, the Big Cam II greatly improved performance; these were a big selling point for these engines at the time. The overall horsepower of this engine was the key reason it outsold the small cam ones. The Cummins 855 Big Cam featured top-stop injectors and one of the largest camshaft diameters on the market at the time. Any old school truck driver from the 1970s will tell you stories about how the Cummins 855 series was the king of the road. It’s difficult to leave these engines off every list of the best diesel engines of all time. The 855 had some flaws, especially when it came to starting the engine in colder climates. The 855 utilizes a lower pressure fuel injection system with 2,200 psi to control the injectors and varying timing specs, oil/water pump, and valve spring pressures. However, a glow plug or a shot of ether should be enough to fix this minor issue, as this engine is otherwise fantastic.

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