[1bighawg]

I have a '64 Chevy one-ton dually with a stock 350 (4K miles on crate motor), new 600 Edelbrock carb, 700R4, '86 rear-end with 3:73 gears. Timing & vacuum are OK. I run about 1600 RPM at 60 MPH. (VDO speedometer accurately calibrated) I am only getting about 9 miles-to-the-gallon. Would a 600 Holley be better? And if so, any recommendations on jetting, etc.?

Ed in Mississippi

[4 Jaw Chuck]

Throw a 454 with a stock quadrajet in there and watch your mileage jump to 10-13 mpg. More power will make it nicer to drive and keep you out of the secondaries, thats why your truck is getting such poor mileage. Have you tried tuning your secondary weights?

[gt2betubbed]

With the amount of weight your dually runs, it's making your 350 run harder to get it going. 4 Jaw is right about the big boy doing better on gas even though it sounds funny. I wouldn't change the carb on it, the Edel's usually keep the mileage down compared to Holleys.

[DoubleVision]

if your to stay with the crate motor, there are some things you can do to help mileage, you need more torque for pulling power, I would go to comp cams or crane cams site and look at there RV cams, some increase milage and are made for towing. a cam such as the edelbrock performer cam would be a improvement, add with it a set of tri-Y headers, dual exhaust, turbo mufflers, a set of spiral core plug wires, a MSD intensifier kit, and a K&N airfilter and fabricate up a fresh air induction system. these small mods will be slightly cheaper than a rat motor swap, and will likely get you the mileage increase your looking for. it would also be of benefit to go with a lower rear gear to slightly increase cruise RPM`s to about 1900-2200 RPM so more torque will be avalible at the higher RPM. but the biggest improvement you could make to your 350 would be to throw in a 400 crank and make it into a 383 with the same mods listed above.