The camshaft thrust plate installs directly to the studs on the timing chain valley cover. Between the thrust plate and the valley cover are a pair of thrust shims (shown on the right). Jesel recommends that the camshaft endplay be adjusted to between 0.010" and 0.015" (adjustment is obtained by removing or installing shims).
Fast forward to today: The belt drive inspiration has evolved considerably. In construction, the belt drive system incorporates a cast aluminum plate to seal the front of the cylinder block from the oiling system. This actually allows for improved oil drain back to the pan, and at the same time, eliminates any power loss attributed to driving the camshaft in a pool of lubricant. The belt itself is intended to run dry. Obviously, there is a provision in the cast cover to allow for the cam stub shaft and the crankshaft to protrude. And of course, these openings both incorporate oil seals.
 The crank pulley is installed by way of this billet aluminum driver. It's installed on the crank in the normal fashion (with a mallet over the driver). You'll note that the driver fits inside the lower belt pulley. Jesel recommends that the seal surface remain dry during the installation. |
Today, there are several manufacturers building belt drives for various (common) drag race engine combinations. In the case of a Jesel arrangement, the belt itself is a proprietary 25 mm wide, round tooth or "high torque" affair. Jesel selected a round tooth belt for one major reason: The round profile of the "teeth" does a superior job of distributing the load across the tooth. As mentioned above, the belt is designed to run dry, and the overall design is resistant to wear from dirt and grit. While initially configured for the small block Chevy, today, there is a plethora of different configurations available for a wide range of engine combinations. Included in the mix are designs for engine blocks with raised camshaft locations. A select few of these belt drive kits feature longer belts with tension idlers (there is no need for an idler on combinations such as standard cam location small block Chevys or standard cam location big blocks). For the uninitiated, raised cam engine blocks have been developed to incorporate much longer stroke crankshafts for large displacement engine applications. In these blocks, the cam tunnel is raised so that the block can accept huge strokes (upwards of 5.00-inches), hence the need for special belt drive configurations.
But we digress: When it comes to idler pulleys and belt drives, they may not really prove to be the best mix. Gates (the maker of many belts used in these drive setups) notes that the use of an idler arrangement leads to heat build up. The reason is an idler pulley can actually spin at speeds in the range of 28,000 RPM. That spells heat, but there’s more too: Having an idler out in the open just asks for more trouble. Here you have one more component that can fail. But as pointed out above, in some cases with tall camshaft tunnels, the manufacturer has no choice but to include an idler pulley.