Although the basic engine design has remained constant for the XE engines there were a few minor changes made leading to the distinction between 'early type' engines (those up to engine number 14142838) and 'late type' engines (those from engine number 14142839 onwards).

The two types of cam belt used on the XE engine are quite easily identified by looking at the tooth profile. The early type engine has teeth with a rounded profile. This is generally the preferred option for engine tuners. The tooth profile itself offers no real advantage over the later belts but the other components in the 'early type' belt train (most notably the idler pulleys) are much stronger. The later type engines have cam belts with a much more squared profile. It is popularly believed that this was to reduce noise - not usually a consideration in a race car!

Most of our upgrade kits include a pair of vernier cam pulleys. Obviously there are two designs of these pulleys to suit the two different timing belts. If you are ordering an upgrade kit please tell us which timing belt you have so that we can make sure the right type of verniers are included in the kit.