I have an 85 F150 with the 4.9 straight 6 cylinder with the C6 transmission. I inherited it from my brother in law a couple of years ago. I have put quite a bit of money and time into this vehicle, as it sat for about 2 years prior to my inheriting it. Problem is this: Gas mileage sucks! It got 15 mpg on the interstate when I got it. I changed the rear end gears from 3.55 to 2.73. Doesn't seem to have made any difference. Engine is carburated. Here is my question, has anyone here changed from the ratty old 1 barrel to a 4 barrel? Wondering if that would help as long as I keep my foot out of it? I realize it is a truck, but It is my primary transportation to work and I am tired of feeding it so much. Thoughts, Ideas...all appreciated. I am close to setting it in the road and setting fire to it.

 

Have heard a LOT of good things about the 4.9L, but fuel economy wasn't one of them. Also, have to consider that with the squared off looks, the truck has all the aerodynamic efficiencies of a brick wall.

In short, I'm not sure you're going to get much better than what you already are, no matter what you do. Best advice I can offer is to ensure the truck is in good tune, not carrying any unnecessary weight, and perhaps consider driving a bit slower to reduce the effects of wind resistance.

At any rate, your setup has proven to be extremely reliable with a long life - I see a lot more Ford trucks on the road from that era than any others. That's got to be worth something.

Not aware of any 4bbl conversions, although I'm sure that with enough time and money and web searches, anything is possible. Not sure if that conversion will yield any efficiency improvements.

 

Thanks for the info. I have pretty much gathered the same idea. As much as I don't like Fords (sorry), it is a nice driving truck. Just LOVES gas!

Jim

 

I miss the carb days. Those I could rebuild, this injector stuff has me confuzlled.

 

I personally prefer the port fuel injection, but mine is carburated. That's a simple set up, but usually not as fuel efficient, either.

Jim

 

Try looking here http://www.cliffordperformance.net/ . They may have some suggestions. They also care just about everything you can imagine for the 300's from 4 barrel intakes to fuel injection.

 

Thanks Snake.

That's a cool site.

 

You might want to take off the air cleaner and check the choke plate to make sure it opens all the way. a stuck closed or even partially closed choke can do a real number on mileage. also keep in mind that the C6 has no overdrive and especially for highway driving, the 4.9 is not designed for high RPM's. I know a lot of people who own the 4.9 straight sixes, and they actually get fairly good mileage. like 17-19 mpg. does the engine seem old or worn out to you?