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soxplayer · 05-16-2011, 10:39 AM

My 2 cents (possible 3 cents at todays gas prices). Keep your speed down. I can get 14 MPG on the highway with a 250, 4 speed and 5.13:1 gears in a 67 C20 with the old model B carb. I have to run 60 with the engine turning over at 3500. The truck is running on the rich side with factory jetting and it has an old LMC glasspack single exhaust. Otherwise it is stock including the ignition system. Tall gear will help but you are fighting bad aerodynamics and a small engine for the load. If you gear too tall you will spend a lot of time with the powervalve open in the carb (yes even a model B has a power circuit) and your gas mileage will go away unless you are driving on flat ground with a tailwind.

05-16-2011, 10:39 AM	#37
soxplayer Registered User Join Date: Jun 2009 Location: Forest City IA Posts: 56	Re: Better gas mileage My 2 cents (possible 3 cents at todays gas prices). Keep your speed down. I can get 14 MPG on the highway with a 250, 4 speed and 5.13:1 gears in a 67 C20 with the old model B carb. I have to run 60 with the engine turning over at 3500. The truck is running on the rich side with factory jetting and it has an old LMC glasspack single exhaust. Otherwise it is stock including the ignition system. Tall gear will help but you are fighting bad aerodynamics and a small engine for the load. If you gear too tall you will spend a lot of time with the powervalve open in the carb (yes even a model B has a power circuit) and your gas mileage will go away unless you are driving on flat ground with a tailwind.