Gas mileage of a 1973 Ford LTD?

Status
Not open for further replies.
Joined
Jan 2, 2017
Messages
58
Location
CA
Last edited:
Early to mid 70's cars were horrible on gas. My mother bought a new 1974 Chevy Nova with a 350 V-8. I drove it from Chicago to Florida once and averaged 10 MPG.
 
Growing up, my dad had a 75 LTD.
Pretty sure it was bad on gas, but probably comparable to the 73 Volvo 145 it replaced (possibly comparable).
 
Single digits I assume. 1973 would have a pellet type catalytic converter, parasitic early smog controls and possibly non-transistorized ignition? 400 CI so it would be even worse than a more modern 5.7 or 5.0 SBC or SBF.
 
Assuming the 5 is really an S, it would be a 400 2-bbl. Expect around 10-12 mpg avg if it's running good and hasn't been modified. Might do 15 on the highway if you keep the speed down. My mom had a 72 LTD wagon with a 460, it would get 8 avg 10 highway. The 2-bbl should do better than the 4-bbl. It won't be as powerful as you'd think, either.
 
.


gas station.png
 
Last edited:
The 400 is not noted for economy. However, if you install a dual exhaust, replace the intake and carb with a good AFB or AVS 4 Barrel carb and order the tuning kit. Then you scour the wrecking yards for a temperature controlled air cleaner that Fits, prefer Chrysler style with the vacuum motor hot air damper and replace the crap Chrysler temp regulator with a GM one. This will let you establish a lean mixture and still be able to drive in the winter. You pick up the hot air off the exhaust manifolds. I would also mod for dual snorkel and twin cold air intakes. Then you need to recurve the distributor for more centrifugal advance and Vacuum advance as these motors ran with retarded timing to make less Nox, Modded like this 15 to 17 MPG is possible, with as much as 19 when the speed limit was 55 ad you drove like an ole lady.. I did one long ago for the first gas crisis Another way would be to convert to fuel injection using on of the many kits and tune for economy. Top speed north of 120 which is all the speedometer said. MPH in quarter mile maybe 85 on a good day If youcange to a RV stule camshaft it can do a bit better. All these mods buy a lot of gas. The payoff will be better running, not savings.

Rod
 
Originally Posted by ragtoplvr
The 400 is not noted for economy. However, if you install a dual exhaust, replace the intake and carb with a good AFB or AVS 4 Barrel carb and order the tuning kit. Then you scour the wrecking yards for a temperature controlled air cleaner that Fits, prefer Chrysler style with the vacuum motor hot air damper and replace the crap Chrysler temp regulator with a GM one. This will let you establish a lean mixture and still be able to drive in the winter. You pick up the hot air off the exhaust manifolds. I would also mod for dual snorkel and twin cold air intakes. Then you need to recurve the distributor for more centrifugal advance and Vacuum advance as these motors ran with retarded timing to make less Nox, Modded like this 15 to 17 MPG is possible, with as much as 19 when the speed limit was 55 ad you drove like an ole lady.. I did one long ago for the first gas crisis Another way would be to convert to fuel injection using on of the many kits and tune for economy. Top speed north of 120 which is all the speedometer said. MPH in quarter mile maybe 85 on a good day If youcange to a RV stule camshaft it can do a bit better. All these mods buy a lot of gas. The payoff will be better running, not savings.



Or just buy a modern car.
 
It'll be around 7 or 8 in town. With a 2.75 ratio and a well tuned 2bbl, you might get 12-15 on the highway if you keep it under 60.
 
Here's the Fuelly on my 1970 Chevelle. Slightly bigger engine than you are looking at and slightly lower rear axle ratio and this is mostly city mileage but it will be in the ballpark for comparison. I drive the car nice by the way (because I am over 50 and don't like attention) and this is all I get for MPG so YMMV.

[Linked Image]
 
Originally Posted by maxdustington
Single digits I assume. 1973 would have a pellet type catalytic converter, parasitic early smog controls and possibly non-transistorized ignition? 400 CI so it would be even worse than a more modern 5.7 or 5.0 SBC or SBF.

No cats. Cats didn't come out till 75.
 
73 was a bad year for all manufacturerrers. Low compression,retarded cam timing and ignition timing we're terrible for gas milage and power. The 400 was likely Ford's most underpowered engine of all time.

The 2.75 gear ratio is just icing on the low performance cake.

BTW that car will have the plastic cam gear teeth that are ready to fall off.

Figure 8 mpg in town. 11-13 hwy. Do some tuning and you may be able to muster 15 mpg hwy under ideal conditions.

A big block would be a better choice for it. Same mpg but enough power to pass
 
Last edited:
Originally Posted by MrMoody
Assuming the 5 is really an S, it would be a 400 2-bbl. Expect around 10-12 mpg avg if it's running good and hasn't been modified. Might do 15 on the highway if you keep the speed down.


THIS ^^

Without Overdrive trans, and PROPERLY tuned (for mileage, not for emissions) you can get 15 if you stay under 60 mph.

Early 70's cars were tuned HORRIBLY, sacrificing mileage to make emissions specs instead.
 
That's a Sunday driver that you put 2k miles on a year because it's cool. Who cares if it gets 8 MPG.
 
Got to keep your foot out of it to get anything reasonable. I couldn't find a chart for 1973, fueleconomy.gov only goes back to....'74.

But I CAN tell you that my brother had a 1971 Chrysler 300 with the 440...if he got on it, he'd get get less than 7. But a friend of his (who does NOT have a lead foot) got 20mpg on a long trip to Florida.

YMMV.
 
Status
Not open for further replies.
Back
Top