rpm and mph neither one are searchable So, I have 4.56 geared axles with 35" tires and a th350 transmission. The carbed small block (350) that came in my K20 didn't even last a year until a rod was knocking, but maybe the motor was just old. Now, I have a TBI 305 to swap in. Will running the engine at 2845 rpm for extended lengths of time be ok? At 55 mph it would be 2407 rpm, which still seems high to me. Maybe I should use my 3.73 axles, but I don't think I'll like the decrease in power, and my 4.56 axles have disks rear and the front is rebuilt.