I found this Forum while looking for a tire diameter chart of all things and thought you might be able to answer a couple of questions for me.
I have a 1954 GMC 350 ser. (2 Ton) flatbed about 8,000 lbs empty;a friend is working a trade for a '91 12V Cummins and NV4500 which I want to install in my truck. I'm currently driving it,but the swapped-in 302 gas six is REALLY tired-it will just barely carry both Overdrives empty,and with even 1000 pounds on it,both boxes are in Direct or lower. (Clark 5 speed w/.84 overdrive,Brown-Lipe 3 speed aux. w/.74 overdrive,stock 2 speed rear with 6.40 top side.) I think this Cummins engine and the NV4500 will be a good set up. I'll be selling the Clark,but will keep the Brownie intact. So far,though,nobody has any ideas for fuel mileage. I'm getting about 8-10 mpg now,and that's if I drive with the Clark in 4th (Direct) and the Brownie in 3rd (Over). If it'll carry 18 mpg empty and go 65 I'll be good with that;I can live with 10-12 loaded (figure a car trailer with a car on it,average load) but more would be better.
Anyone got some ideas? I read about the best rpm for mileage. According to my number cruncher I'd be doing about 2,000 r's at 60 mph-not as good as I'd hoped. 2500 rpm would give me about 74 mph;I could dial it down a bit to increase the mpg's. Thanks in advance for your input.
BTW-I live in Elko,and go to Reno fairly often.