Does anyone kinow what the peak torque rpm is on, say, a '51 216? I would think that, like a diesel, the engine's full-power operating range would be between peak torque and peak horsepower speeds.
Stuart said,"I have seen folks indicate that the combination of heavy cast pistons and babbitt rod bearings require a light foot in these old engines."
As a truck engine is clearly designed to be run frequently at open throttle, I can't see that statement being correct, and the one time I've had 3000# of timber in Epic's box, she seemed very very pleased indeed to be pulling hard. In fact, she seemed happy at 45+mph, and when she's empty, 40 is plenty.
Lower rpm's are better for fuel economy, provided that the engine is not allowed to lug. A lug condition exists when the engine is operating at a speed less than peak torque rpm at full throttle. If the engine is allowed to lug for too long, heat will build up in the top of the combustion chamber, and the risk of burning exhaust valves is sharply increased. The cure is to back off the throttle, or downshift.
