fuel mileage

Re: '73 351 Cleveland with an updated Holley mdl. 2300 500 cfm 2 barrell

I am getting about 10 mpg with my Ranchero which is not a hot rod. Apparently the previous years were but I understand that '73 was the first year that HP was reduced in order to improve mileage due to the oil crisis. The horsepower, according to the data plate decode is a whopping 164.

Is this poor mileage normal or can someone provide information that will help get the MPGs up, even a bit. I get better mileage with my F350 Super Duty 7.3 pulling a 30' 5th wheel trailer!

 

Clevelands were kept through '74, and the changes Ford made (called IMCO, meaning 'Improved Combustion') were never applied to Clevelands at all, as they were replaced for the '75 MY by the 351M/400. BUT, even with Duraspark ignition and a 2150 carb, it's gonna be around 10-12 MPG. You could install an overdrive unit or an Automatic Overdrive trans, as it'll bolt up to the Cleveland block, but sadly, unless you get an emissions-friendly cam with the cam retard offset machined into it, you won't be able to get much more MPG from the engine. Don't get me wrong, Clevelands are stout and great runners when kept correctly in tune, but they're a bygone era engine.

 

What rear gears, tire size, stock converter, ignition specs? Not trying to argue with what Andy posted above but if the engine/trans/chassis is decently healthy and operating correctly, I would say 15-16 mpg isn't out of reach. Even my 472/C6/3.25 combo gets 14-15 mpg and it isn't stock.

 

Keep in mind the 500 CFM Holley is well known to be a bit of a fuel hog, way bigger than the original 2V carb, so the mileage will suffer some. Have you tried moving the timing up a bit? Vacuum advance hooked up and working properly? There's a bunch of power and mileage in the tune-up when optimized.

 

My '74 Squire had the 351-2V/FMX and a 2.74 rear end with 215/75/14 tires. All I could ever get was about 12 when the points, condenser and even the breaker plate early on, and a whole new dizzy later on, and all settings to spec. Oh, and the 2150 was also a reman. I had fixed all the vacuum leaks, always kept the plugs clean and correctly gapped, and it had a new timing chain and gearset after it was rear-ended, pretty much no change in its max MPG.

 

I had a 1966 2 door Ford custom (full size) with a 289 and cruisomatic with unknown rear ratio and I swear on the highway that would get phonomenal fuel mileage.
I am guessing around 15 to 18 mpg ( I don't know for sure never really clocked it)

But as a young man when cruising around town I spent little on fuel and on long trips it would sip gas.

 

Back in the mid 80's I had a '75 Cougar with 351w/C4/3.0 gears with points ignition('70 Windsor engine swap) riding on Firestone G70-14's bias ply tires and it got 17.5mpg, I lost a bet with my uncle on it's mileage the reason I remember. In '89 when my current '79 Ranchero had a mostly stock smog era 460('68-'71 timing set) and C6 sourced from a '76 T-bird with open 2.50 rear gear it got right at 17mpg with 225/75/14's using a Holley 9834 600VS with an "OK" fitting intake A-dapter to fit the square bore Holley to the spread bore intake, I could never get rid of that mid rpm whistle . Running about 1900 rpm @ 60 mph and having a good tune up has a way of saving fuel.

 

After driving my Ranchero around some, I decided not to even attempt to figure out what kind of mileage it gets. I topped it off (8 gallons), drove it to work and back, then to a car show, then topped it off again (9 gallons). That's almost 18 gallons for not many miles. Nice it takes high octane too.

 

I've never got better than 11 mpg average in the close to 40 years I've had my 79. 72 and up Rancheros weigh a lot. I've never seen anything from Ford listing their weight which I suspect is probably about the same as the full size pickup. Most of my trips are local in the city so overdrive isn't worth the effort or expense. If I go somewhere out of the city I just use the wife's car.

 

I may have misrepresented my mpg numbers, these were both quoted as highway #'s, average was a bit lower but would truly say that they still gave back over 13-14 average. Sorry for any confusion. I believe I saw a '77-'79 Ranchero curb weight as being around 43-4500 lbs, depending on options of course.

 

That's one thing I hadn't considered, was checking just my highway MPG. I always checked my overall MPG; Babe gets around 16 overall. So perhaps my Swore got good highway MPG, but I never checked just that.

 

However, a vehicle's overall fitness should be checked on overall MPGs anyway.

 

On the Freeway... If I am over 60 MPH, I get 9 to 10 mpg... 55-60, I can get 14, with my 428CJ with a 735 double pumper 4V - C6 - 225/14 tires.
Overall is about 9...

Mid/late 70's after the OPEC gas crunch, sucked for the car industry, and car lovers!

 

I'll check my registration (Washington State prints a vehicle's curb weight on it), but I seem to recall mine weighed in when new, around 3700-3800, and it had the M engine and A/C. When I do, I'll snap and post a pic.

 

I truly appreciate all of the replies. To answer the previous questions related to the potential of effecting MPG, here goes:

Rear tires are 23R/60R-15 Cooper Cobras, the actual curb weight at the scales (with Gem Top canopy, one-half tank of fuel, and me) is 4360, it is a 500, has a 3.00 rear-end ratio, and an FMX trans. New plugs, wires, rotor, and cap plus Pertronix, smog crap removed, vacuum lines replaced (no leaks), vacuum advance works properly, and the timing is set correctly. It has PS and PB but no AC. I run non-ethanol 91 octane (spendy) gas. I just got it out of the hot rod shop - the mechanic owns and races two drag cars - and it runs very well. Typically I drive 55-60 and keep my foot out of it. Sorta looks like there's not much room for improvement . . . . .

 

When you own these dinosaurs they are for enjoyment and pleasure, if fuel mileage is that much of a concern then buy a Prius. Enjoy your ride. Skip

 

I would try giving it a couple more degrees of timing and see if it improves (without pinging). Certainly worth a shot.

 

In my case, it's a 60s muscle-ish car. In any case, with any classic vehicle, it's all about the Smiles Per Gallon!

For the record, my 289 gets 12-ish MPG in town. I don't know about highway mileage yet, because I'm still fighting problems with overheating.

Joseph