One of the great aspects of the Advanced Engineering Technology Conference is the relaxed atmosphere of both the engine builders in attendance and the engine builders presenting. The engine builders in the crowd can sniff out an advertising sales pitch in a second, and the presenters know it so instead we simply get the hardcore truth.

Dan Jesel started Jesel Valvetrain Innovation because he wasn’t able to buy the rocker arms he wanted for his engine building business. But his valvetrain innovations have made the valvetrain company so successful that it has become what he’s famous for.

The Multiple Benefits of a Shaft Mount Rocker System

Not only does a shaft mount rocker system improve stability, it also allows you to relocate the rocker arm’s pivot point without having to weld up and redrill the holes in the head.

Most everyone knows that shaft-mount rocker arm systems are an improvement over standard pedestal mount rockers because the shaft design provides additional stability. But shaft rockers also have another, very important feature over pedestal rockers that you may not realize.

Typically, a shaft mount system works by bolting a stand to the cylinder head that has cradles for bolting up the shafts. Jesel says one of the reasons he originally designed his famous shaft rockers was because he was trying to figure out how to install longer big block rocker arms on a small block Chevy. The ratio was the same but the longer arms of the big block rockers improved the geometry between the roller tip and the valvestem.

Instead of redrilling the rocker stud holes, Jesel simply moved the cradle back on the stands. This moves the rocker pivot away from the valve so that the arm can be longer. A longer arm, in turn, creates more clearance for larger diameter springs, it reduces the angle of sweep across the tip of the valvestem, and it allows higher rocker ratios without moving the pushrod cup right into the rocker body.

Mike Moran’s Pro Mod Engine

Jesel worked with Mike Moran to develop a clean-sheet engine design for Pro Mod racing. The engine is absolutely stuffed with innovation, but what Jesel talked about is the innovative cam design.

If all you have ever seen is a stock small block camshaft, this new cam design will hardly be recognizable. The large billet cam is ground on a massive 82 millimeter core. The lobes are incredibly narrow to help cut weight, and the bearings are actually captured in large “clamshells” which are then pinned to the block to hold them still. With a standard cam, the lobes can’t be any larger than the bearing diameter in order to be able to slide the cam into the block. A larger diameter makes it a lot easier to grind very agressive lobes, but the large diameter bearing surfaces that go with it makes the bearing speed too fast. The clamshell design allows for incredibly large lobes alongside small bearings for reduced bearing speed.