The 948cc and 1098cc A-Series engines used a distinctive tappet cover arrangement on the side of the cylinder block that is not found on the later 1275cc or 1500cc engines. This side-mounted cover provides access to the cam followers and is secured by screws with a cork gasket.
948cc and 1098cc Pushrod and Follower Differences
The earlier small-bore engines also differ in their pushrod and cam follower design from the 1275cc. While the operating principle is identical, pushrods transferring camshaft movement to the rocker arms via bucket-type cam followers, the physical dimensions of these components differ, and they are not interchangeable with the larger engine. The camshaft profile also differs, reflecting the lower power output and different rpm characteristics of the smaller engines.
948cc and 1098cc Parts Availability
Parts availability for the 948cc and 1098cc upper engine components is more limited than for the 1275cc, as these engines were produced in smaller numbers for the Midget and parts demand is correspondingly lower. Sourcing for specific items should be confirmed before commencing rebuild work, particularly for the tappet covers, their gaskets, and the earlier pushrod specifications.