I have a 1986 F150, 6 cylinder, 300CID, I think. Four speed transmission although I usually start from second because first is geared sooooo low.

Gas mileage is dismal. Does anybody know of any bolt-on items to improve it? Or would a different ratio rear end help very much? And if so, which one? And would you know if it's available?

And do you guys know of anything not too major to make the ride more comfortable?

I've got the old truck looking and running pretty well. It's not going to be used for real work, I'm mainly just trying to keep it preservable and drive it enough to keep its legs stretched. It was my parents' only new vehicle and I plan to sort of pass it down through the family as a collectable.

Thanks in advance for any help anybody might offer.

 

What is your truck getting in m.p.g.?

 

Why not just get it tuned right and not spend money for mods.
Depending on the compression, the best you'll ever get is maybe 17 or 18 mpg.
The 4 speed overdrive is commonly available, mine sees 20 on the highway.

 

Sometimes that right foot can effect gas mileage.

 

Thanks, Ben

I should have mentioned in my first post that I was talking about mileage when the truck is tuned and running well and probably performing at the high end of its efficiency. I didn't know there was an overdrive available. Is it a big deal to install?

 

All I can tell you is there was a 4OD tranny in the early to mid 80s, then a 5OD later 80s.
You might post on the six cylinder forum...also maybe a tranny form.

 

I wouldn't waste my time with the 4 speed OD. In mountain terrain, and if you decide to haul anything, heavy, you will be replacing clutches left and right. IMO.

What you could do to gain a little horse power and gas milage is to change the Flex fan with a clutch fan.

Replace the shocks. Worn out shocks can cost you gas mileage, and cause rough riding like you describe.

Put smaller tires on the truck. I wouldn't go smaller than what's recomended on the saftey sticker however. make sure they are balanced and got equal Air Pressures.

Change out your lower gear ratio with a higher one. I wouldn't go higher than 2.75 though.

My truck with P225-75-R15 tires, (which is one size bigger than stock, and I will be going one size smaller P215-75-R15 to squeeze every last drop of MPG out of her), 2.75 gear ratio, T-18 four speed, with a clutch fan, gets an average of 21 MPG.

A buddy of mine with the same exact setup, except with a 4-speed OD tranny, and air conditioning, got an average of 25 MPG. But for what he saves in mileage, he spends on clutches. 6 clutches to only replacing 3 on mine, and mine has twice the miles on it.

I have an add that says the 1981 Ford pickup F-100, F-150, 4.9L had and average of 21 MPG, according to the 1981 EPA's MPG guide on the add. One truck tested got 28 MPG, and another got only 14 with the same exact equipment, so it was like a crap shoot, and say's about as much in the add.

 

mileage? I get 9... empty, loaded, up hill or down....

if I put it in 4 wheel, it drops to 5...

 

howler, funny how the milage doesn't vary much weather loaded-unloded, uphill-downhill, but 9 m.p.g? ouch

Is this driving over 85 m.p.h.? (kidding)

 

My truck is more or less a keepsake. It was the only new vehicle my parents ever owned and was worked pretty hard in its youth. It only has about 76K miles on the clock, which I consider pretty dern good for an 86. It's only loaded now and then when I help a neighbor bring home a new refrigerator or some such thing. My essential plan for the old thang is to keep it running and preservable and drive it enough to keep its legs stretched. I'm going to hand it down, hopefully, through the family. I have a 1 year old grandson. By the time he's ready to drive, the truck will be 35 and pretty collectable, I'd think. It's basic transportation, more or less, and of course the mileage is what you'd expect from a work truck that was working hard. I think the clutch fan might be one option I'll pursue and of course I was about to replace the shocks, anyway, and I know that can help a little with mileage.

I really appreciate all y'all's interest. Thank you

 

Don't understand why people are having trouble with clutches on the 4OD.
I've had my 83 since new, has 173000 miles, did one clutch at 100,000 miles, not because it was bad, only cause I pulled the tranny due to a bad bearing.
My only limitation with the 300-4OD combo was trying to backup a 2500 lb 22 ft travel trailer, UPHILL. It wouldn't go. Mine is the Supercab and 8 ft bed.
So take your pick....good mileage is possible, at some limitation.