CV Products' XTS camshaft...
CV Products' XTS camshaft beltdrive is an entire system of components designed to work together for optimum cam timing with minimum vibration.
For years, beltdriven timing drives have been the accepted standard in NASCAR Nextel Cup racing. The same holds true in the Busch Series and Truck Series as well as other top touring racing series. The reason is that a belt system has several advantages over a traditional timing chain. First, and probably most important, the belt is capable of absorbing harmonics from the camshaft to help keep the valve timing under control. A belt also doesn't stretch like a timing chain over time, so there is no "slack," and it requires less energy to operate, meaning more horsepower makes it through the drivetrain. Finally, because the belt isn't splashing in oil like a timing chain, and the camshaft cog is infinitely adjustable, camshaft timing changes are much easier and quicker than on a chaindriven system.
Although there is no machining...
Although there is no machining necessary, it is a good idea to make sure there are no interference issues between the billet back cover and the engine at the high points of the water jacket around the number-one cylinder. You can do this by placing a few balls of clay on the cover and test-fitting it against the block.
Of course, the downside of a belt system has always been the cost. At several times the price of a timing chain set, this option has, in the past, been reserved for teams willing to spend big bucks for every last fraction of horsepower available. But that's changing as the cost of a quality camshaft beltdrive system is decreasing and many lower-level teams are realizing the worth of investing in such a system. One advantage of a beltdrive system is that the components are quite stable and durable. Even Cup teams, who are notorious for throwing away engine parts, normally only replace the drivebelt after a race and leave everything else in place.
CV Products is now offering a camshaft beltdrive kit under its Xceldyne brand that is one of the most affordable yet. With a list price of $853, the XTS Pro kit includes everything needed to set up your timing system. For $1,000, the kit is upgraded to the XTS Elite and includes a cam thrust bearing to replace the standard shim. The XTS kit is currently available only for the small-block Chevy, but there are plans to expand it to Mopar and Ford engines as well. One of the features of this system is it uses no idler pulley, which is common on other systems. This is intended to reduce additional drag and make the system simpler by reducing components. Instead of using an idler, the included belt is a snug fit with carbon in its construction to minimize the possibility of stretch. The teeth of the pulleys have been designed around the cogs of the belt so that mesh is exact and the camshaft timing is extremely precise.
CV says that its system for the Chevy small-block requires no block machining and can even be retrofit to an existing engine. To find out what is involved in installing a camshaft beltdrive on a race engine, we took Xceldyne's Pro kit to KT Racing Engines in Concord, North Carolina, and asked them to install it on one of their rebuilds. We could have chosen a new engine build, but we felt that trying to see if this system could work with a short-block that had already been built to work with a timing chain would be an even tougher test.
As you can see, we have plenty of clearance for proper oil drainback. If it is too tight (less than approximately 0.010 inch), you may need to remove a little material from the block with a hand grinder. There should also be some clearance between the back of the cover and the front of the front main cap to allow oil to drain back into the pan. If there isn't, you can cut a groove or take a small amount of material off the front of the cap.
Install the crankshaft seal with a little red Loctite to hold it in place, and then work the included O-ring into the groove in the back of the plate. Cut off the excess and place a dab of silicone sealer on the cover at the edge of the oil pan rail. There is no need for a gasket. If the timing cover rail on the block is gouged or nicked, you may wish to supplement the O-ring with a thin film of silicone.