>From Chilton's MG Manual
YEAR Engine Disp HP@RPM Torque Bore and Comp
oil
code
@rpm Stroke ratio press.
61-62 9CG 948 46@5500 53@3000 2.478x3.000 8.9:1
30-60
63-64 10CG 1098 55@5500 62@3250 2.543x3.296 8.9:1
30-60
65-66 10CG 1098 55@5750 65@3500 2.543x3.296 8.9:1
30-60
1967 12CC/E 1275 65@6000 72@3000 2.780x3.200 8.8:1
40-70
68-70 12CD 1275 62@6000 72@3000 2.780x3.200
8.8:1 40-70
1971 12CJ 1275 62@6000 72@3000 2.780x3.200
8.8:1 40-70
1972 12V 1275 62@6000 72@3000 2.780x3.200
8.0:1 40-70
1973 12V 1275 55@5500 67@3200 2.780x3.200
8.0:1 40-70
1974 12V 1275 50@6000 67@3000 2.780x3.200
8.0:1 40-70
1975 PE94J 1493 57@5000 71@3000 2.900x3.440
7.5:1 40-60
1976-9 PE94J 1493 55.5@5000 67@2500 2.900x3.440
7.5:1 40-60
US Version
1976-9 PE94J 1493 48@5000 ----------- 2.900x3.440
7.5:1 40-60
California Version
Hope this is helpful in answering the compression question,
Dave
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