 The kit includes this aluminum timing chain valley cover. Basically, the cover seals off the original timing chain area in the cylinder block, which in turn, allows the belt drive to run "dry". This arrangement seals the front of the cylinder block from the oiling system. Improved oil drain back to the pan is one benefit, and another is the elimination of any power loss attributed to driving the camshaft in a pool of lubricant. As you can see, there is a provision in the cast cover to allow for the cam stub shaft and the crankshaft to protrude (both incorporate oil seals). |
The first solution was to eliminate gear drives, and believe it or not, use a timing chain set with a nylon upper gear (this was a common Chevy production piece at the time). It worked to a certain degree, but as you can well imagine, this approach required constant maintenance. Chains and timing gears were replaced regularly. And because of the construction, a racer was never quite sure if and when the chain (or nylon sprocket) screamed: "Enough". The consequences could either be a lack of performance or considerable engine carnage.
Forward Thinking…
The solution was a brainchild of Dan Jesel. Jesel noted that many foreign cars (and at the time, a small handful of domestics) along with a few motorcycles incorporated belt drives for their overhead camshaft arrangements. As the story goes, Jesel was deeply entangled in a project which involved adapting a pair of overhead cam Cosworth Vega heads to a small block Chevy (eventually destined to reside inside his and brother Wayne's Camaro gasser). While a Midnight Auto Supply thief cut the project short, the belt drive camshaft concept remained. It was simple: What if a similar arrangement could be engineered for a common pushrod engine such as the small block Chevy? Engineering the system was likely far more difficult than the inspiration, however the process also brought about several innovations that made the belt drives even more appealing to the racer. Aside from the belt absorbing significant amounts of crank-to-cam harmonics, the belt drive also took less power to drive (when compared to a timing chain or gear drive).
This piece is the camshaft adapter. The purpose is simple. It mates the snout of the camshaft to the top belt pulley. You'll note that it's keyed and machined with a taper so that the spider fits tightly. The adapter physically bolts to the camshaft snout, and has a provision for the cam drive pin. Jesel supplies a special spanner wrench (shown to the left of the cam adapter) that allows you to hold the cam in place while torquing the camshaft adapter bolts.