The Stovebolt Site Forums The Shop Area Driveline safe rpm for chevy 250 engine

with a 1948 3/4 ton chevy truck with a rebuilt (30,000 miles ago)250 cu in chevy engine with standard 4spd tranny and 4.56 rear end , (rebuilt brakes, shocks and sway bar etc) and 16inch radials, what is the rpm that is safe to run. I have calculated that at 5o mph the rpm is 2556, at 55mph 2811rpm, at 60mph 3067 rpm and at 65mph 3322rpm (i don't have a tach). there is info on this forum regarding the 235 but not much on a 250. I don't think I want to change my driveline and know that mpg goes down as rpm increases. I get about 12 mpg at 50 t0 55 . I guess the question is whether it is a good idea to run it above 55mph for very long thanks for all the help

besides how much money you want to waste on gas, how fast you run it for how long is directly related to how long you want it to last .... I wouldn't call holding max RPM with any engine a "good idea"

Bill

Thats a tough engine if it was o-hauled good. High rpm wont hurt it if not tortured. Like Red says its not good to drive prolonged periods at high RPM. It will use a lot of gas. If you are going to be on the highway a lot I would look into an o-drive.

thanks

I agree with what you said, given that drive line what would you consider a high rpm?

thanks again

I'd say 2800-3000 is about as high as you'd want for extended periods, less would be better - with the 3/4T gearing, 50-55 is what I'd expect and what the truck was built for

Bill

thanks bill

that was what the truck was telling me too