A friend who owned MGs in the 60s and 70s gave me a copy of a 1974 Chilton's
MG manual (hardback cover--don't see that these days) and a Unisyn balance
meter for tuning carb air flow (interesting device).
But as a I was thumbing though the Chilton's, I came across the engine
comparison's of different years:
Year Eng Size Carb Type Horsepower Torque Bore&Stroke
Compress Oil
74 18V 1798 HIF4 (2) 63@5000 87@2500 3.160x3.500 8.0:1
50-80
73 18V 1798 HIF4 (2) 81@5000 97@2700 3.160x3.500 8.0:1
50-80
72 18V 1798 HIF4 (2) 92@5200 110@3000 3.160x3.500
8.0:1 50-80
71 18GK 1798 HS (2) 92@5200 110@3000 3.160x3.500 8.8:1
50-80
Years 72-74 are the same engine and carbs, but the horsepower (lost 33%) and
torque (lost 21%) is quite a bit different. All had smog pumps and none had
catalytic converters. Year 72 changed the carb and lowered the compression
from 71, but didn't appear to make a performance difference.
Were the differences a function of how the car was tuned? (emissions?)
Or, was there some other difference?
Nick
73B
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