more mpg
Posting Guru
Joined: Aug 2000
Posts: 1,127
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From: (near) Denver USA
more mpg
>how can i get more mpg
>out of a 351M?
78bronco,
Sorry, no magic bullets. The only things I have ever seen that you can do to improve mpg on the M-blocks (351M/400) are:
1. Keep the engine well tuned.
2. Inflate tires to maximum pressure.
3. Go easy with the right foot.
Mechanically, keep the engine in the best state of tune you can. Make sure plugs and wires are good. Change the distributor cap and rotor every other plug change. Route the spark plug wires to avoid cross-fire.
Make sure all the external components are operating correctly (i.e., the PVS and temperature sensors). Make sure the vacuum hoses are routed correctly and not leaking. Make sure the carb is clean and adjusted properly. (The biggest changes I've seen in fuel economy were realized with a freshly rebuilt and properly adjusted carb.)
Keeping the tires at maximum pressure (as specified on the sidewall) reduces the rolling resistance and improves mpg some. The tradeoff is that the tread contact patch is not optimal at maximum pressure, unless the weight you're carrying is near the tire's maximum load rating. At maximum pressure and less than maximum weight, you'll wear out the center of the tread faster.
The biggest factor (by far) in mpg is driver behavior. If you drive modestly, it may be less fun, but the gas will go a lot farther. Some people claim that a 4V carb and good exhaust system, when driven modestly, will give better mpg than the stock 2V carb and factory exhaust. Seems plausible, but the right foot discipline is the critical factor.
If you drive the truck empty and with saintly discipline, you will use less fuel. If you're towing a load or driving aggressively, you use more of the engine's potential power, and consequently more fuel.
In my 5700# F250 (351M, NP435 manual tranny, 3.55 axle gears), the best I see in my normal city driving is about 10-11 mpg. Under favorable conditions (not too many hills) on the highway, I can see 12-13 mpg.
BubbaF250
>out of a 351M?
78bronco,
Sorry, no magic bullets. The only things I have ever seen that you can do to improve mpg on the M-blocks (351M/400) are:
1. Keep the engine well tuned.
2. Inflate tires to maximum pressure.
3. Go easy with the right foot.
Mechanically, keep the engine in the best state of tune you can. Make sure plugs and wires are good. Change the distributor cap and rotor every other plug change. Route the spark plug wires to avoid cross-fire.
Make sure all the external components are operating correctly (i.e., the PVS and temperature sensors). Make sure the vacuum hoses are routed correctly and not leaking. Make sure the carb is clean and adjusted properly. (The biggest changes I've seen in fuel economy were realized with a freshly rebuilt and properly adjusted carb.)
Keeping the tires at maximum pressure (as specified on the sidewall) reduces the rolling resistance and improves mpg some. The tradeoff is that the tread contact patch is not optimal at maximum pressure, unless the weight you're carrying is near the tire's maximum load rating. At maximum pressure and less than maximum weight, you'll wear out the center of the tread faster.
The biggest factor (by far) in mpg is driver behavior. If you drive modestly, it may be less fun, but the gas will go a lot farther. Some people claim that a 4V carb and good exhaust system, when driven modestly, will give better mpg than the stock 2V carb and factory exhaust. Seems plausible, but the right foot discipline is the critical factor.
If you drive the truck empty and with saintly discipline, you will use less fuel. If you're towing a load or driving aggressively, you use more of the engine's potential power, and consequently more fuel.
In my 5700# F250 (351M, NP435 manual tranny, 3.55 axle gears), the best I see in my normal city driving is about 10-11 mpg. Under favorable conditions (not too many hills) on the highway, I can see 12-13 mpg.
BubbaF250
