Bucket Tappet guide bore

A bucket tappet guide bore comprises a fitting bore 3 which is a sliding fit with bucket tappet 2 and a guide bore 4 having a clearance fit with the bucket tappet 2. This arrangement avoids jamming and tilting of the tappet 2 on assembly, thereby making it easier to slip the bucket tappet 2 into the guide bore 4 in an automated manner. A Chamfer 5 is also provided to further enhance the assembly of the bucket tappet 2 in the fitting bore 3. In order to ensure good precentring, the guide bore 4 is made long so that when a valve is opened the bucket tappet 2 is pushed into the guide bore completely, by a cam, so that wall 7 projects above the bucket tappet 2. To avoid the cam striking the wall 7 two diametrically opposed recesses 8 are provided.