1986 F150
4.9L stock w/Duraspark 2 [recurved]
EGR deleted; still running both original catalytic converters
1970 Carter YF carburetor from a F350
SROD transmission
3.08 limited slip
215/75 Michelin LTX M/S [35PSI front, 32 PSI rear]

I have kept all gas receipts for years and check every one for mileage. Most of the time, the truck is filled up at the same pump at my favorite station. I drive the same distance to work, church, play, etc. so my mileage is very consistent, more dependent on weather conditions than anything else. I do not have GPS, but have checked the mileage on the interstate and for 10 miles, the odometer is off by plus 1/10 [1%].

My commute is an urban one, being 13 miles one way. About 1/2 of that is in town with many stop signs and traffic lights followed by rolling farmland at 45mph.

I rarely exceed 2000 RPM. Basically, 1st gear to 12 or 13 mph, 2nd to 25 or 26 mph; 3rd to 45 mph and then shift to OD. If the speed drops to 40, I downshift to 3rd.

I keep the receipts in my wallet until I think to transfer the data to my log book, so today, I will share the most recent 6 fill ups and the results. During this time frame, the cost per gallon increased from $3.50 to $3.79 which is an increase of 8.3% in about 5 weeks.

3/4/12 207.7 miles 12.237 gal. 16.97 mpg [mild temp.]
3/10/12 153.5 miles 8.486 gal. 18.09 mpg [mild temp.]
3/18/12 203.1 miles 11.564 gal. 17.56 mpg [mild temp.]
3/26/12 200.7 miles 10.682 gal. 18.79 mpg [mild temp.]
4/3/12 207.1 miles 11.812 gal. 17.53 mpg [warm temp.]
4/12/12 195.1 miles 10.875 gal. 17.93 mpg [warm temp.]

My average mpg for this time frame is 17.78 mpg [1167.2 miles/65.656 gallons]... not bad for a 26 year old bull nosed brick!

 

That looks like pretty good mileage to me.

 

Just a quick update...

Since the previous post, I have gone through 3 more tanks under the same conditions and have averaged 17.93 mpg.

This past weekend, I made a road trip and did better...

5/4/12 225.6 miles 11.303 gal. 19.96 mpg [hilly @ 55-65 mph; 25 miles town driving]
5/4/12 191.7 miles 8.604 gal. 22.28 mpg [hilly @ 55 mph]
5/6/12 184.5 miles 8.902 gal. 20.73 mpg [hilly @ 55 mph; 30 miles town driving]

At 55 mph in O.D. = 1500 RPMs; up hills @ 55 in 3rd = ~2050 RPMs.

Sometime in the future, I want to drive on a really flat stretch @ 55 mph and see what it does.

By the way, gasoline is now $3.48 [down from 3.79], so it has decreased by 8.2% in about 4 weeks.

 

Wow! Thats pretty decent. It's probably due to the air cleaner and air intake tube. Of course if it was that simple, everyone would have done that. Before I pulled the 300-I6 out of my project I was getting about 15-16, but I've got 3.55 gears out back.

I'm sure that SROD tranny combined with 3.08 gears out back are in a sweet spot when it comes to sipping fuel.

Ron

 

For anyone who wonders what that is about... Ron provided these items for me some time back. Thanks, Ron!

 

Reminds me of my 84 F250 MPG's, avg around 17.5 till I put EFI on it(done before FTE existed!), dropped to 13 to 14 MPG..... Offy DP and DS2 going on when I get it back running!