My '62 C-30,when stock,averaged 10 mpg loaded or empty at anything under 50 mph,and dropped to ave. 7.8 mpg at 65 or more mph. After the 5.14 gears were swapped for 4.10's my mileage improved by about 2 mpg across the board.The mileage didn't change at all when I pulled the deceased 283 and installed a 350,or when I pulled the 350 and installed a freshly built 355. (Still haven't figured that out...)I'm thinking the gearing is pretty much deciding my fuel economy numbers. I'm swapping my Holley 600 four pot for a Q-jet that's been re-bushed and worked over by the owner of Custom Tuning here in Elko. He indicates that'll be good for at least 3 mpg without any other work,and swapping to a 3.73 rear will help even more.If I had a couple more 17.5" wheels,I'd go back to them on the front;they stand the same height as my current 235/85-16's,but are a narrower tire,thus,less rolling resistance. Anybody want to trade two very good 8X17.5 radials on duallie wheels straight across for a pair of 1-1/2 year old 235/85R-16's on new duallie wheels?
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