I just got back from the first road trip in a couple of years (about 500 mi round trip) with my 76, thought the results of the changes I've made were interesting. I checked the milage on the same trip to my place in northern Wisconsin a few years ago with a tired 360 w/single exhaust and 600 performer carb,3.50 rear, no load in truck, got 11 mpg. Checked milage today with fresh 352, mild cam, Flo Tech hedders, 600 performer carb, 3.00 rear, about 600 lbs of gear and two adults on board, got 12 mpg. Odviously the potental for fuel economy isn't why we love these old trucks. BTW, the truck worked flawlessly the entire trip.

 

That's crazy.

I've got an old, sick, tired 351M running on about 6 and a half cylinders...and often get 12 mpg highway.

 

OK finaly filled mine up to check milage. Keep in mind I have the C6 behind the 302 so was expecting about 17-18. Much to my surprise I am getting 21. I didn't think my odometer was right so I went to a mile marker and drove it out my milage turns 9 tenths per mile. So I reckon my milage is even alittle better but either way it beats the heck out of the 13 I was getting with the 360/C6

 

I never expected my truck to get phenomenal mileage, but something isn't right getting 11.

I used to regularly get 20 with a built small block olds in a 79 chevy- a 302 with a 2bbl ought to be able to manage 15.

Anyway, I started my tune up yesterday, with a new coil and cap/rotor. The old cap was pretty trashed. I still need to do the plug wires, and I know that will help too, since my ohm meter tells me a couple of them are bad.

Also, it appears as if I have a small fuel leak coming from the throttle shaft. Is this a common thing? Can I re-bush the shaft?

Thanks for all the input- this place is great!!

Andrew

 

My 77 had a trashed 400, by trashed i mean sounds like an old 7.3 when you first fire it up thanks to a few rod bearings. 31" tires and 4.10's netted me 8 mpg no matter what. Whoever mentioned the vacuum reading thing, that is not 100% but damn close, the only way to get closer is to dyno your engine and drive at the rpm with the most torque. Which is the the rpm that will have the highest vacuum so long as the engine is in really good mechanical shape. With a 302, youre looking at about 2700 rpm ballpark. The only thing you can do from there is make the engine more eficient via good exaust with some tuned headers maybe, a cam that will let the poor smog'd out turd run and a 4bbl intake/carb as noted above. 4bbls get better mpg because the primaries are smaller than on your 2bbl because the duece has to work at all rpms where the primaries on your quad only work under light to normal conditions. This doesnt work if you drive like me tho... the sound of those secondaries screaming horsepower to you at 4,000 rpms is just to good.
Oh, and upgrade your ignition, stock fords in the 70's are only putting out about 7,500 volts to the plugs. A good ignition with about 25,000 to 30,000 is worth it in the long run, i give my MSD stuff credit for around 1.5 mpg.

 

you prolly have a bunch of vacuum leaks, thats what i had when i got my truck, a couple hours of changing hoses under the hood and a resevoir, you should see an improvement.