'A' Series BMC IMPORTANT Supplied are 2 screws. Replace the original bolts with screws after modifying cover plate. Manufacturer's Statement: Rollmaster are C.N.C. machined, high tensile steel sprockets using double row O6B-2 chain. Care must be taken to inspect key & keyways & shafts for damage before fitting. Do not use pin punches as damage will occur. Use a drift such as a pipe or sleeve. Machine to suit the boss area. No responsibility will be taken for improper fitment or usage or damage incurred. |  | 0 | STD cam timing | | A | keys to left of STD mark will adv cam timing | | R | keys to right of STD mark will rtd cam timing | | 2 | 2 degrees | Keys at crank will give a value of 1,2,3,4 degrees ADV or RTD at the camshaft. The ratio is 2:1. | | 4 | 4 degrees | | 6 | 6 degrees | | 8 | 8 degrees | |