A-6513-Al valve spring has been obsoleted. The new valve spring A-6513-A2 can be easily distinguished from the old design as the free length of the new spring is 2 15/16”; the free length of the old spring is 3” 7/16. In addition the new spring has 11 left hand coils whereas the old spring had 15 right hand coils. (See Fig. 964.) The old and new designs can be used interchangeably. The list price of 10c each applies to either type.