I would not say the old motors got bad fuel mileage. I had a 444 Cummions thats was rebuilt with ALL the goodies via Diesel Injection of Pittusburgh. She dynoed out at 720 to the GROUND after the overhaul yet still got 7.5mpg running Streator IL to Ferdonia NY grossed out at 80K all the time. The truck was a 88 International 9370 set forward axle with 60 in flat 3.55 rears and 13 Double over tranny I could not even use 13th gear unless I was going 70 or better. That truck routinely pulled Snowshoe in PA if I was sent to Philly with bolt blanks we came back with honey going back to Streator so we were heavy I could hit Snowshe at 65 and be at the top doing 62 not to bad. The biggest factor in fuel milage is called the DRIVER in the seat. My mother can not get better than 22 MPG in her van my father when he drives it gets 26 what is the difference the driver.

 

I read that the driver effects fuel usage upwards of 35%. Our old B model was idled all of the time and got 5-6 mpg most of the time; we could get worse if we had a head wind out west or other such aggravation.

Put a driver in it when we moved up and the drivers generally got 4 or 4.5 out of the same truck. When we got tired of the drivers I went back to driving it and the mileage was just as good as it had been. All of our drivers had 10 or more years exp just didn't drive efficiently and didn't care what the mpg were, just how fast they could get from A-B.

My 425C model that got 6+ was built to 600+, it gained mpg when it was built and avg'd over 6 and was also idled all of the time. I'm sure it was getting 7+ driving economy pulling heavy@ss chickens at a high rate of speed (that was before I became a 'run compliant' law abiding citizen ).

Now that I at least keep track of fuel mileage, we'll see what an old 'B' will do.... If it looks like all's okay when we do the bottom and top; we'll run it stock for a while before adding HP, so I'll be able to document that difference as well. I don't really care if it gets 4mpg, but I just bet it'll get 6+.... we'll see. :wink: