fuel mileage ?

F

Ford Freak

Well-known member
Hey guys ! What kind of fuel mileage should I expect to get with a ' 37 coupe equipped with a stock , (good condition )'42 59A , '39 trans , 4:11 rear , and 27 in. tall rear tires ? - Thanks in advance !
 
Well, tell us what mileage you are getting and what kind of driving you are doing. In town, highway? Then the folks can chime in and let you know what they think.
You tell us then we will tell you.
John
 
Under normal driving conditions around town is approx. 7 . It might be a tad better on the highway , keeping it under 3,000 rpm .
 
Well, As a comparison: Our 46 4 door with a new rebuilt 59-ab, 3.78 rear, 600:16, (but I have a Mitchell O/D) gets 17/18 mpg on trips. Mostly secondary roads and some interstates (60-65 mph). This is accurate. No exaggeration.
John
 
I got 18.25 MPG on my trip out west for the National meet in 92. 39 Merc coupe, stock engine. That is all highway miles Close to 6000 miles round trip.
 
ford38v8 said:
No such thing as a '42 59AB either. The 59 series engines came in 1945.
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That's what I thought also . I thought the former owner said it was a '42 , which I found a bit confusing . Then again , I may have misheard or misunderstood him . I knew it was a 59 series , and that's all that mattered to me . Either way , thanks for the info .
I also found out in my owners manual that my tank is 14 gal . ( I thought it was 16 ) and did some new calculating .
I figure now that I'm getting 10 mpg . Not great , but better than 7 that I originally thought ! I think I'm going to do a gear change .
Thanks again - F F
 
I would think 15ish is normal. I get around 15 in both my 49 and 41 and I usually have a combination of city and highway. 7 seems low.
 
10 mpg is a bit heavy for any old Ford. You'd get that from a 59 Caddy. You probably have an over rich condition in the carb. There are many threads on here re 94 carbs and getting them to run right. There may also be other inaccuracies in your calculations. things like fuel leaks, fuel sloshing from the tank on turns, stuff like that.
 
It's all in how you treat that long skinny pedal (or the button in the earlier stuff). Also how far you wind out the 1-2 and 2-3 shift. 9 outta 10 over rev antique engines but today's traffic and drivers (no consideration) sometimes demand it.
 
Based on standard gearing and tire sizes, if the engine is in good tune, the carb has no internal leakage, and the ignition vacuum retard system is functioning correctly, you should get near 12 to 14 MPG driving around town a lot on the stop & go side with no jack rabbit starts. 17 to 19 mpg should be close on the highway if you have good gearing for the highway. Overdrive will get you there easily but a 3.78:1 ratio without OD will be on the low MPG side due to the higher engine rpm at current highway speeds. A 3.55:1 ratio can do the job as long as the transmission gearing is set up for that ratio. The size an weight of the vehicle plus the tire size all have an effect on the mileage.
 
I used to think I got only 10/12 mpg until I serviced and calibrated the speedometer. I had been able to get the speedo fairly close using a different sending gear but then it wasnt recording the mileage properly. Now with the odometer reading correctly milage figures out to around 20 running a 3:54 rear end.
 
I think you are calculating based on size of the tank vs. gauge reading (i.e., 1/2 tank = 8 gallons)? The only accurate way is to fill it, keep track of miles, and refill it to the same level (based on gas pump shutting off or by looking thru the filler) and noting mileage.
 
I'm not sure what tank size (capacity) has to do with figuring gas mileage. The problem may be not knowing how to calculate mileage? Fill the tank up and record the mileage, drive it until the fuel level is down to say 1/2 or 1/4 tank, refill it and record the mileage. The difference in the mileage divided by the amount of gas to refill the tank will give you the MPG. The size of the tank is not a factor in calculating MPG. Also, any one check of MPG is just a single test point. You need to check it over time and find the average. As stated above, you also need to check your speedometer for correct calibration.
 
I have a 39 Ford coupe with a stock 40 or 41 engine (dual exhaust) and 4.11 rear axle.
No large tires.
I get about 17 MPG. No hard driving, etc., no overdrive.
A different axle ratio would be better, but I'm too old and lazy to make the change
 
JSeery said:
I'm not sure what tank size (capacity) has to do with figuring gas mileage. The problem may be not knowing how to calculate mileage? Fill the tank up and record the mileage, drive it until the fuel level is down to say 1/2 or 1/4 tank, refill it and record the mileage. The difference in the mileage divided by the amount of gas to refill the tank will give you the MPG. The size of the tank is not a factor in calculating MPG. Also, any one check of MPG is just a single test point. You need to check it over time and find the average. As stated above, you also need to check your speedometer for correct calibration.
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I originally thought I have a 16 gal. tank . When it was down to 1/2 after x amount of miles , I figured I went through 8 gal. during those miles . Then I found out I have a 14 gal tank , and instead went through 7 gal . in those same amount of miles . So in this scenario the size of the tank is a factor , as I realized that I went through less fuel than I had originally calculated . I know how to calculate fuel mileage , but got a little messed up here because a: thought I had more fuel for 1/2 a tank and b: my speedo is off a bit . However , I know the distance between my house, and a friends to be 15 mi. , so I base it on that w/ 2 round trips . Hope this all makes sense !
Thanks for your reply - F F
 
You are guessing at how many gallons you are using.

Figuring half a tank is 8 gallons or half a tank is 7 gallons is not close enough.

Fill the tank to FULL either by the nozzle shutting off or by sight in the filler neck.

Drive a fixed number of miles.

Refill the tank to the same level as before...this will tell you EXACTLY how many gallons you used withou guessing "was it 8 or was it 7....?"
 
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