The Stovebolt Site Forums The Parking Lot Big Bolts '48 1.5ton 235ci/SM420 MPG

I have a little more then 500 miles on my rebuilt 235, with SM420.
Most of my driving has been stop and go in town, top speed of 45.
The truck is a stake bed, with dual rear wheels, and weighs about 6000lbs.
When we rebuilt the motor we went to standard crank bearing inserts, aluminum pistons, and stock style cam.
I have been tracking my fuel economy for the last two tanks, and so far I am averaging 6.5mpg. To be honest I thought i would be getting 8-9.
Does anyone else know what they are getting?
This is strictly a curiosity question, I love my truck and thoroughly enjoy driving/working on it, regardless of the fuel economy.
Thanks,
Curt

You must remember that you are having to move 6,000 lbs from a standing start every time you take off from a traffic signal. Also you must remember that it is 60 year old technology. And if you get to highway speeds, the old girl is not very aerodynamic. Your fuel economy might go up a little once the engine is broken in, but I wouldn't expect a whole lot more. I think you are about average for stop and go. Our 2 ton GMC bob tails used to get around 5 when we were hauling gasoline with them.

Crenwelge, I had most of that in mind, I was just curious what other big bolt owners are getting. With my rearend having 6.17 (or so I think) 3000rpm @ 45mph I don't even entertain highway speeds!
How much fuel were you hauling? I have not had a load since I rebuilt the motor/drivetrain. But I did haul 6k with my '48 once, it was on that trip I decided I needed to rebuild my brake system. Luckily I had no problems!

The tanks that were built in the 40's were around 1500 gallons. By 1955 tanks were built lighter which allowed us to haul 2000 gallons. We thought nothing of running our GMCs around 3500. We ran 9.00x20 tires.

My '53 GMC 2 ton, w/ 302, head milled .060", 5 speed direct, Brownie, flatbed, 6.6 ratio, usually got 13-15 MPG at 60 or so, load or not, on the flats, lower in Mtns.