Dowel type exact timing adjustable toothed belt cam drive system.
This comes as a complete kit to convert from chain drive.
The adjustment is by interelating holes between the cam boss and cam gear. Located by a dowel. The holes give 2 degree increments of adjustment. Combined with a 1 degree offset key it facilitates EXACT timing of the camshaft. Fits all A Series engines and includes a breather pipe take off.
Fitment of an uprated cam drive system is essential when building a performance engine. Timing scatter induced by the standard set up can reach up to 15 degrees once the single row chain has stretched, which it does after only a few miles. This scatter not only affects the cam timing, but also the ignition, the distributor being driven by the camshaft. Power loss suffered by this phenomenon is substantial. Replacing the standard single row (simplex) system with a dual row (duplex) system greatly reduces the problem; use of a toothed belt system all but eliminates it. The belt system vastly reduces valve train noise and also helps damp out some of the odd harmonics generated by the 3 main bearing 'A' series engine. It is also extremely important to time any cam in to its required setting to obtain maximum performance, especially with performance cams. The 'dot to dot' method can, because of manufacturing tolerances, be out by as much as 15 degrees. Anything above 2 degrees out and power suffers -- most noticeably in small bore engines. In race engines you probably lose 1 hp for every degree the cam is out, more when over 6 degrees!