Okay Guys i bought a ford F250 that has a straight six with a bull dog 5speed tranny. I am worried more about reliabilty and gas mileage rather than how fast i can make it go. in order to get maximum fuel economy would i be better off with my 300I6? also would is the most MPGs i could squeese out of her?thanks in advance.
Is your truck 2wd if so I think 15-17mpg would be about normal in a truck that heavy, might be able to do a little better if you drive like an old lady but I would be surprised to ever see an F250 get any thing in the 20mpg range, not sure all my 300s have been in 1/2ton short beds or broncos and they have all gotten in the high teens to low twenties on a great day with a tail wind, I think your truck won't quite get there due to its extra weight. The 300 will get better milage than any of the other motors offered in these trucks except the diesels.
I agree with you. I used to drive a 1980 F250 I6 with granny 4 speed as a work truck. It was always loaded down with work stuff. It got 15 to 17 MPG. On the other hand, later, I drove a 1994 F150 5 speed(OD) with I6. It got between 10 and 12 MPG on a good day. Mechanic that checked it out several times said it was normal for that engine.
When people on this site say "good" gas mileage, they mean "good" as in it's "good" compared to a 460. With these old trucks, 15-20 mpg is good when most V8's are getting 8-12.
By the way gradrgy, 10-12 mpg on an EFI 300 with overdrive means something is wrong. You should have been getting around 20. Why should an EFI 6-cylinder with an overdrive gear get the same gas mileage as a 3-speed 400 cubic inch V8 with a carburetor. No offense, time for a new mechanic.
What fmc400 said. "Good" and "better" are highly irrelevant without a comparison and even with a comparison can still lack definition. With a properly tuned engine the largest single factor that has anything to do with mpg is driver habit.
And what optikal illushun said about the engine swap.
If my f250 w/460 could average 15mpg I'd be happy with it, but it's really just to much truck for that kind of mileage to be expected. Useing these large trucks for daily drivers is becoming too expensive for some owners. A short bed, 6 cylinder would work better for me.
how difficult would it be to replace my 460 engine with a built up 300 in my 1993 4x4 automatic f-250? No emmissions here to worry about.
Considering that you'd have to replace your entire drivetrain, it would take a while for the money saved in gas to even it out. For the money you'd spend on the swap, you could buy a Ford Escort and get almost 3 times the mileage you'd get out of the 300. Trying to get better mileage out of giant pickup trucks is a lost cause. The world is changing and these trucks aren't going to rule the road forever.