Custom Harley Davidson Evo Engine - 96-Inch Evo Build

This month we are ready to pick up right where we left off on our 96-inch Evo build project. When we last worked on the motor, Eric Bennett of Bennett's Performance had just finished installing a set of JE Pistons, Axtell iron cylinders, and some high-flowing STD heads. For this installment we will be working with TP Engineering Pro-Vent billet rocker boxes, roller rockers, Andrews Products adjustable pushrods, and AB Tech pushrod covers. By the time we finish up today we should have the motor complete with the exception of the Compu-Fire charging system, Mikuni carb, Dyna ignition, and pipes.

We chose to go with the TP Engineering Pro-Vent rocker boxes (part No. 250-20; MSRP: $875) for a few different reasons. First and foremost, Evos are notorious for oil-carryover problems. If you are not familiar with carryover, see HOT BIKE, Vol. 38, No. 5, p. 107 for a detailed explanation. TP's engineering staff took a long, hard look at carryover and designed the company's Pro-Vent rocker boxes to, if not eliminate, certainly reduce the effects of carryover. They accomplished this by designing a series of passages and holes in the rocker box that separate the oil from the air, allowing the oil to flow back down to the bottom of the engine. Not only do the Pro-Vent rocker boxes deal with carryover, they are constructed of billet and are very stout. This lends itself to better control of the valvetrain due to decreased flex when compared to stock pieces. The sturdiness of the boxes also helps isolate valvetrain noise to the interior of the boxes, translating into a quieter ride. And if that weren't enough, we liked the fact that the boxes, along with all of TP's other components, were made right here in America. TP's roller rocker arms (part No. 45-0245-23; MSRP: $339.99) were a perfect choice to complete the top end. The pieces from TP's Pro Series line include a forged 4140-steel design and roller tips designed to reduce friction in an effort to free up every drop of horsepower hidden inside the motor.

Since Harleys ship with non-adjustable pushrods, we tossed the stock ones in favor of a pair of Andrews EV80 EZ-Install pushrods (part No. 292245; MSRP: $120) when we disassembled the motor. In addition to ease of use due to their adjustable design, the Andrews pieces are manufactured from chrome-moly steel for superior strength and rigidity, while still remaining lightweight. Considering how good-looking the motor will be when we are finished with it, we wanted to go with trick pushrod covers that would add to the overall look of the motor. While there are many choices out there, we decided to go with a set from AB Tech (part No. 10-22C; MSRP: $235). Not only do they look great, but they are also sturdily built from solid aluminum rod, then polished and chromed for a brilliant finish.