The engine codes for US Cleveland motors are:
H - 2V (small port) heads and 2 barrel carburetor
M - 4V (large port) heads, 10.0:1 or 9.7:1 compression ratio, small 4 barrel carb, mild hydraulic lifter cam, 2 bolt main block.
Q - 4V heads, 8.8:1 or 8.0:1 compression ratio, large 4 barrel carburetor, Cobra Jet hydraulic lifter cam, 4 bolt main block, dual point distributor.
R - 4V heads, 10.1:1 or 9.0:1 compression ratio, large 4 barrell carburetor, solid lifter cam, 4 bolt main block, dual point distributor, fordged pistons.
The 1971 Panteras had M code motors, the 1972 - 1974 Panteras had Q code motors. DeTomaso never installed an R code motor in a Pantera.
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