Hey,66Submarine! i have a '55 Chevy T.F. 6500/261/SM420/2-speed rear,(not sure of gear ratio's). Engine tag states XXX H.P.@ XXXX R.P.M. I know that I achieve peak horse-power @ 3500 R.P.M.,which I believe is the "norm",for medium/heavy trucks of the '40's and '50's. Once up-to speed,I can drive 55,all day long,without having to down-shift either the trans,or rear-end. I still have about a 1/2-inch of pedal before "She" hits the floor,but I know the sound of a "Happy" engine. Don't expect more than 6-8,(if you're lucky),M.P.G. I pulled the data-plate from an old WHITE WB22T semi-tractor,(about a '48),and that engine peaked at 3500 R.P.M.,as well,but for the size of that flathead 6,it only achieved 122 H.P. It was rated at 40,000 G.V.W.,(tractor/trailer comb.) It had a 5-speed main box,with a 3-speed auxy.,to help it achieve highway speeds,without over-stressing the engine. Average M.P.G.,(as I was told),was 3-4 M.P.G. The 292's didn't come on the scene,until about '63,and I'm not familiar with the data on these engines. Most engines built in those days had a life-span of 100,000 miles,on average. If not worn too badly,they could be re-built,with an expectancy of another 50,000 miles. Hope this helps.
Last edited by wetwilly5757; 05/30/2013 11:06 PM.
