Original A-Series

Open tappet chest, two tappet covers.
Front cover usually has oil vent/separator.
All 850-1098cc engines and all Cooper S engines are similar to the illustration.

"1300" Type

Engine I.D. plate/serial # location

1275cc only. Closed tappet chest. Oil breather on timing cover or flywheel housing. These engines were originally used in Austin 1300/Austin America cars, hence the "1300" name. A+ engines are similar but have additional ribs on the outside of the block for reinforcement.

Closed tappet chest engines that use Cooper S type rods (1.625" journal) may be identified by a "thin" mounting flange at the transmission case split. The thin flange is 3/16" thick, while the thick flange is 5/8" thick.

A+ blocks may be identified by the distributor clamp bracket. A+ blocks use a fork shaped clamp, with one bolt through the clamp into the block. Pre-A+ blocks used a clamp held to the boss by two bolts, clinching the distributor with a bolt and nut through the clamp.

Cylinder Head Identification

Cylinder heads may be identified by their casting number, located between #4 and #5 pushrods.

General identification is as follows:

• 850-1100 heads have a heater tap at 90 degrees to the centerline of the engine. The space between the thermostat housing and the valve cover is small, at 1/16".
• 1275 heads have their heater tap at an angle. The space between the thermostat housing and the valve cover is 5/8". Cooper S models had an additioanl head bolt (A) and stud (B). (This is an easy modification for other 1275 applications, not a sure indicator.)

A quick test can be made in that if you can put your finger between the base of the heater tap and the valve cover, the head is "big bore" 1275 or 1300cc type.