Thread: 240 or 300 for 6 wanted

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I am looking for a 240 or 300 ford 6 to install in a 70 F250 to try to get better gas mileage and the 360 and C-6 that are in it now are very tired,I have a couple of AOD trans that I would like to install behind the six to see if I can get 20 mpg out of this truck as it might have to make a few trips to work as I drive 45 miles each way. If there is anyone with ina reasonable distance from dayton ohio that has a rusty 67 to 79 ford p/u with a good six I am intersted in it.

Well don't look to a straight 6 if you want better gas milage. You gotta gear em way up because they don't make enough power so you'll be screaming down the highway at 4000 rpm which I don't think will help your gas milage at all. Also, straight 6's like to put their pisons through the oil pan when you run them that high because they have a huge bore and stroke. Face it, you drive a truck, they get bad gas milage. Your milage will be lower because your engine is worn out, so you should just rebuild it with some more compression. Get the block zero decked and that should rais you half a point. Then mill the heads some to get the rest of that point. Don't go crazy with your camshaft selection and give the motor some more ignition advance than the manual advises. Most smog engines run 4-8 degrees to reduce NOx emissions, but they get the best fuel economy and power from 8-14 degrees advance.

My dad had a 86 E150 short wheelbase van that had the 300 and a automatic overdrive and it got aroud 21 MPGs on the highway so I figure I can get similar mileage doing the same with the 70. His van was a conversion and probably weighed about the same as my F250 so I might be able to get decent mileage from that combo and this truck does not haul much mainly brush to the dump and a engine now and them plus I use it for junkyard trips. Years ago I had a 67 C-20 with a 250 and 4 speed with 4.11s that got 18 to 20 on the highway,now that was with the 55 MPH speed limit but I think I can coax some better gas mileage from a six and a automatic overdrive for highway cruising.