970 & 1071 S blocks are about 1/4" shorter in height than 1275 S and non S 1275 blocks, so the height difference and the bore size means its probably a small capacity S. There should be a tag with the capacity attached to the back of the block next to the casting bump where the fuel pump goes on mechanical fuel pump A series engines.
AEG163 is an S head. From what I understand these came in two versions, yellow and blue. This refers to the colour painted on the top of the head under the rocker cover. The yellow heads had a tendancy to overheat and were replaced by the blue head which used a modified casting to improve cooling.
Re the 9FC engine prefix.
9F is an engine prefix used for minicooper engines irrespective of capacity or type (S, non S etc) Exception is the UK MK3 S.
The F means twin carb engine and is used on other BMC engines as well
Don't know what the C means.
Checked my workshop manual circa 1971 and it shows 9FC as the prefix for a 970 S. It also shows 12FA as the prefix for 1275 S engines which is wrong so the C is probably wrong as well. 12FA is a prefix used for engines in cars such as MG1100s etc which used a twin carb non S 1275 engine. Looks like somebody at BMC got their numbers mixed up.
Just to add to the confusion my MK1 S gearbox has a 12FA prefix for the the gearbox number.
RonR
. Funny you should mention the stroke a quick measurement gave me around 62mm.
