What should rpms be on the expressway? Its a 92 roller block with aluminum heads, stock c-4, and 3.55 gears... I feel the rpms on the highway are high what should a normal range be running around 70 or 80mph? Could it be the tach? thanks
Ditto, depends also on the rear tire diameter. My Comet with a C-4 and 3.50's turns about 3100 rpms at 70 mph, possibly a bit more with whatever slippage there in in the torque converter. (26.6 tire x 3.1416 (Pi) = 83.6 circumference, that divided into 63360 (inches per mile) = 758 revs per mile, that times the gear ratio (3.50) = 2653 rpms @ 60 mph. 60 x 1.166 = 70 mph, so 3653 x 1.166 = 3095 @ 70 Ain't Algebra fun ?
Yes it is... I just want to know why I was forced to sit through all those painful english classes all through school and into college.
Ugly teacher huh ? That's why I didn't go to college. Never understood algebra till I got into hot rodding and engine building. If someone had bothered to explain to me that all those letters used in the formulas were representing numbers, it would have made things much easier.
Typically with standard tires your engine will turn 3000 rpm at 65 mph with 3.5 - 3.55:1 rear gears. That speed is not hurting your engine as long as it runs at normal temps. It it is overheating then the oil can lose its surface tension and cause wear - just like at any rpm. Paul
Sounds like you're either in second gear or the tach isn't set for a V8. Should be a switch on the rear of the tach to set it for 4, 6 or 8 cylinders
its an old tach we found it in the garage and used it... pretty sure its set for 8 cylinders but ill double check
upon a closer look it was not set on 8 cylinders...which would probably explain the problem...and Im sure my neighbors love me now, nothing like making sure the tach works at 10pm!!!
