A 600 horsepower 14, 15, or 16 liter diesel engine requires 1600 CFM. The 15-inch diameter filters are 1700 CFM each giving the engine 3400 CFM of air. We all know the duel Vortox polished stainless-steel air filters equipped on the newer Kenworth, Peterbilt, Western Star, and Freightliner Classics are beautiful, but they are also functional. The older J series Cummins, 237 Mack, and the 671/8V71 Detroits all required less than 800 CFM. The small cam Cummins engines that were 335 horsepower and lower only required about 850 CFM. Please keep in mind that the older low horsepower and smaller cubic inch engines do not require a lot of fresh air measured in CFM (cubic feet of air per minute). This article will be about a commonly overlooked problem when installing a newer diesel engine into an older truck.

There’s something special about the rebuilding of “Old Iron,” a Class 8 truck from the mid 1970’s and older. You can’t have a reliable high performance diesel engine without this extra attention to detail.Many of us who have been in the trucking industry all our lives, and even some younger people, have a fascination for antique trucks. They are then tested, checked for leaks, and calibrated to match flow. If the customer wants to keep their original set of injectors, we can perform what we call a “clean and check” where they are disassembled, cleaned, and reassembled with new O-rings. Now the owner-operator has a blueprinted set of injectors all match flowed. First we do the leakage test to check the barrel and plunger tolerance, check the plunger to injector cup for leakage and seating, and then the recalibration to increase the flow for more horsepower, and then adjust the top stop setting. Our new injectors are from Cummins ReCon. For injectors, we like to setup and blueprint every set of new injectors. We work with the customer to pick the best code for each application and set it up according to their needs. There are thousands of pump codes for different horsepower and torque curves.

It then goes on the pump stand to be tested. We then reassemble the pump with new springs, gaskets, seals, and O-rings. With the pumps we start off by disassembling them, cleaning, and replacing all worn parts. Many ask us what all goes into rebuilding fuel pumps and injectors.

350 big cam cummins