I've had my 1965 Flareside 240ci, 3 speed, oil-bath air cleaner for 2 years and just this week I've had the "opportunity" to drive it everyday as my regular vehicle blew its transmission. My drive to work is mostly interstate, 60 miles roundtrip. As this is the first time I've actually used the truck as a daily driver, I decided to its was a great time to calculate the miles per gallon. Surprising, I'm averaging 15mpg.

So, how does this compare to the MPG your 240 may be getting? Any suggestions for improving the MPG?

 

I have a 390 and I'm scared to find out!

 

Don't be,, I'm getting 13 with my 390 4x4 4 speed with 3.50 gears

 

I just rebuilt a 390fe for my 1965 F100. Bore .30 over/ .495 lift Comp hyd cam/ Edelbrock alumnum heads/and intake manifold/ 750 holley vac seconds/ 4speed/ 4:11 9' rear. Hwy and normal driving 10-12mpg, when I heavy foot it 8mpg....

 

Don't have a 240, so I can't say, but 15 is pretty good.

To improve mpg, better ignition, induction, exhaust, more compression, and overdrive. These are not necessarily cost effective. If you plan to continue to use it as a dd, they could be worthwhile.

 

That's excellent for a 390. My 64 thunderbird with the 390 gets about 9. I was surprised when my 62 f-100 (292 + 4 speed + unknown diff) turned in about 12-13.

~Steve

 

I've been getting 7-ish MPG lately.

 

Hey, thanks for all the replies. Anyone with a 240 have any feedback?

 

The standard routine - tire inflation is an easy one. You may recall how difficult it is to pedal a bicycle with underinflated tires!

A tuneup will help efficiency. Make sure the ignition is in top form - from battery - ground straps, cables, plugs and wires, etc. if you're running points you would see a slight gain from running electronic ignition. Even occasional misfires (undetectable) waste fuel. Old spark plugs will misfire as well. Keep an eye on plug condition.

Replace engine thermostat periodically, to ensure quick warmup. There is usually an improvement to be had by advancing engine timing as far as practicable, and make sure vacuum advance is working properly. You're not going to see massive increases by doing these things but every bit helps. What happens is things degrade slowly over time so as you'd not really notice, esp. Ignition.

A side benefit is a well tuned engine will always start in hot or cold weather, warm up quickly, and pollute less.

 

I have a 56 f 100 with a 302 new plugs and Pertronix II distributor, FMX no overdrive transmission and 3.54 Dana 60 and I get a little over 13. I just changed to the Pertronix distubtor this spring. It not only added electronic ignition but also vacuum advance. It was only 10 mpg before with the old distributor.

 

I've had my 300 inline six for a few months. Stock, 3.50 gears. C4 Automatic.
I drive a few days a week locally, and get just under 13 mpg. But I did drive it 300 miles freeway once, and I did a very accurate check through 100 miles on a nice flat stretch of freeway at exactly 55 mph. I figured that's the best mileage I'll ever get.
It did just about 17 mpg.

 

I don't know how to accurately measure MPG when there is no consistent shut off point when filling the tank on these older vehicles. Oregon is a state where you can't legally pump your own gas. The places I go let me though because they know me by now and fear my wrath when they can't figure out why the pump shuts off moments after they put it in. In my state, unless you have a modern federally regulate intake on your tank, the attendants are lost. I learned years ago when tiring of them drenching the outside of my motorcycle tank to not let them pump this truck.

What I did to test was fill until I could tell the fuel was up in the filler tank, and I was getting 14.7 MPG on my 240. But, I don't like to run with that much gas as it can expand and flood the carb. Also, with recently installed fuel sending unit and doing eyeball averages, the 15 MPG mark seems about right for the 240 for shorter commute times, and warmup, tinkering, etc. On a road trip I would expect a little over 15.

 

I am getting 13.5 cruising at 65-70 with my 460 and 3.50 rear gear but I have OD.

D

 

65-70? I think I top out at 40 haha.

 

I hope you are kidding, at least a little bit. I've got an old 352 2 barrel and NP435 and Dana 24 transfer case with 4.56 ratio in the rear and dragging 4x4 around and I can hit 90 if I want to. I just push on the gas pedal harder...



And this 352 is not exactly fresh, either. Lol.