Jumping in from another thread, I like the reply from Tech1 above. The Speedway catalog says the Rhoads lifters decrease the duration by 10-15 degrees and valve lift by 0.020"-0.030". Then if we take Isky's 256/256 square cam as optimum for economy AND torque one should be able to run a 268 duration cam with Rhoads lifters to obtain the performance of say a Comp Cams 268 above 3000 rpm (?) and something like the 256 torque cam below 3000 rpm. With my 2.79:1 ratio rear I should be able to cruise in high gear between 2000-2500 rpm in "high torque" mode, but still be able to wind it tight in low and second gear with added performance as if the engine had the 268 cam. The question is what is the change-over rpm? Indeed the oil pressure probably be the tuning device here and probably a stock oil pump is advised rather than a higher pressure/volume pump. I know some Japanese cars have variable duration cams and yet rodders disparage "rice burners"; here is a chance to make the best of an invention available to rodders for at least 30 years and get all THREE: Mileage, Torque and HP increases over stock. Are the Crane lifters quieter than the Rhoads? Maybe the Crane Tech people know the rpm range at which the lifters pump up tp full performance?

Best Wishes,
Don Shillady
Retired Scientist/teenage rodder