[SD455DJ]

I have a '70 Lemans with a SD Performance 461 (4.25" stroke 400 + .030") with an M20 (2.52 1st) and 3.08 rear gears (7.7616 multiplication ratio) and it doesn't require excessive slipping of the clutch to get moving. It does have 9.5 to 1 compression and a Bullet RAIV copy cam with 1.50 rockers, but still makes tons of torque down low. With 27" tall tires it runs at 2900 rpm at 75 mph.

My 455HO GT-37 has its original 3.31 12-bolt rear gear, but I swapped out the original M-13 3-speed for a BW-ST10 with the 2.64 1st gear (8.7384 multiplication ratio). This HO has 8.6 to 1 compression and doesn't require any more clutch slippage than normal. Feels about the same as the Lemans with higher compression despite the 0.9768 ratio advantage of the HO. With 27" tall tires it runs at 3100 rpm at 75 mph.

More compression seems to compensate for higher 1st gear ratios.

Dennis