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rgshafto

Gas Mileage

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So, with with the summer old car driving season coming up and $4.00 gas on the horizon, I'm curious about what kind of gas mileage people are getting with their flatheads?

The best I can do with my '36 Sixes is about 16 highway, 13-14 around town (which is most of my driving of course). Not much better than a modern SUV, and this from a car touted as the "economy leader" that year.

We don't have much Ethynol here, but I'm guessing mileage is worse with that mix?

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Most of the gas I use has 5% ethanol. I drive about a thousand miles a month, half in town and half in the country. I drive the car to keep up with traffic in the city and cruise about 50 to 55mph on the highway. Over all I average about 19 mpg. Before ethanol I averaged about 19 1/2 mpg. The only difference now is that I use NKG sparkplugs and only have to change them every second year rather than every year when I was using AC's and Champions. Are the plugs better or does the ethanol make them last longer. I don't notice any other difference. Highway mileage alone is about 20 to 20 1/2 mpg and city mileage can get down to 16 in bad weather.

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Could be a little on the low side. But cars didn't get very good mileage back then.

Smaller cars like Ford, Chev, Plymouth would average about 17 or 18, maybe 20 with a good tuneup.

Heavy models like Cadillac V8, 15 or so.

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Gas milage? Mine is lousy, but what you going to do! I'm driving a 1950 4 door Chieftain Delux with an eight and a hydromatic so I do not expect a lot. Runs in the 14 MPG range for me. I do a lots of driving with the car loaded down like a Mack truck, and I'm sure that doesn't help any. On the flip side of the coin, it only got 11 MPG when I first started driving it. Getting the right oil, tune up, tire presure, and all that ther stuff you are supose to do really made a difference. That's like a 25% increase. Lukey

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Hi Rick, ouch 12 mpg's gotta hurt with these gas prices. Not driving it to So. Dakota this summer I guess? :-)

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I'm envious of some of your numbers. I get about 10 mpg in town and maybe 14 or so on the few times I've had my 49 Streamliner on the highway. It's an 8 with manual transmission. Most of my outings are less than 10 miles, and in my neighborhood there's a stop sign almost every block, so it's probably not a good sampling of what the mileage could be. I still have fun though.

Bill

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No, I'm not going to POCI in South Dakota, don't know what criteria they use to choose locations, must be a drag strip out in the middle of nowhere, I'd rather attend the Flathead Reunion in St. Michaels, MD in early September. All pre-1955 Pontiacs and Oaklands, friendly folks who dress in period style and fun non-competetive 40mph activities! See the Early Times Chapter website for details. Thanks. -Rick

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I have a '32 6 with rebuilt engine but I am not running my original Marvel carb yet. When cruising around town I seem to get in the 12-14 mpg range. On the road when I am touring I get 15-18 mpg. That is curising in the 45-55 mph range. I am hoping when I rebuild the original Marvel that I may do a bit better.

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Try a straight 8 with dual carters maybe 12 mpg on a good day. I do have a progressive linkage I am going to try and it runs very well with fuel in proportion to all the clinders

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Today on the I5 cruising at 55-60 mph in 85 degree heat I drove 99.5 miles using 7 gallons of gas. 15 mpg with the original marvel carb. If I drive 50-55 I get about 18 and on a really good day driving 50 mph steady 20mph is the bst I can do.

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My 48 convertible,straight 8, manual trans, has been as far south as Savanna, Ga. I live in central Ohio. The old girl runs a steady 15 mpg @ 55 mph. I wont keep up with traffic, the engine really screams at 70 mph. I think she would do better if I could get those 4:11 gears out and replaced with a better ratio.

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4:11 was the high end ration in '36. I'm planning on switching out my mid-range 4:44 a 4:11 set in hopes of improving my mileage.

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Speaking of gas...what advice does someone have as to an additive I should be using on an original setup 8 cylinder 1950 Chief? I imagine I should use the highest octane gas avail but do I or should I use an additive for further octane or lead?

Also, what about oil? What kind of oil weight do you suggest for the same setup, approx 96k miles?

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I have a 1950 Chieftain 2 door sedan delux, straight six and I have been averaging around 10-11 mpg as best I can tell. I have been pushing it more >60 mph to see what she can do.

Seems like I should be getting better gas mileage, especially for a six. I typically use 89-93 octane and I a 20w 50 oil and I occasionally add the "mystery oil" additive to a tank.

Others seem to be getting better mileage with larger engines. It starts to get very expenses even just cruising around. Any suggestions would be appreciated!

Thanks,

Christopher

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We took our '53 Chieftain to Virginia at the end of May for a Pontiac show and averaged 16.5 mpg for the 1,250 mile trip. It has the straight eight and Hydra-Matic and we kept our speed to an indicated 55-60 mph; (53-58 actual) I use regular unleaded, (87 octane) and Pennzoil 20W-20 in the crankcase. The car is tuned to factory specification plus I've got the octane selector advanced 2 degrees. I don't believe the engine has been overhauled as it does use some oil, especially when we drove through the mountains. It used 3 quarts of oil for the trip. I usually get nearly 600 miles to the quart around north central Ohio where its nice and flat.

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Those numbers from previous posts are really terrible. Old technology cannot be changed, but we still use the same formulas, IE: horsepower:weight. 1950's cars are very heavy, tend to use small engines (by today's standards), and high rearend gear ratios (4.11:1? C'mon). The diff in gas mileage between a six & eight and city vs highway was small.

How is it that my '90 Mustang (cast iron 289 w/AOD) gets 17/25-MPG? Sure it's light, but wayyyyyy over powered by at least 100 HP. Is it the EFI? Gear ratio (2.7:1)? Radial tires? 10W-30 oil? Maybe it's the whole package wrapped into one.

From our hotrod days, we learned about diminishing returns, and a beneficial compromise: Why install a six when an eight uses just as much gas, but produces more ponies?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 50silverstreak</div><div class="ubbcode-body">Others seem to be getting better mileage with larger engines.</div></div>Rather than change your classic into something it wasn't, learn to enjoy your car for its originality. The price of gas and oil in the 1950's was a non-issue. At 4 Gal/buck, you could fill the tank for $4-5.

Let's count our blessings. Owning classic cars is extravagant but rewarding. As a hobby, it's costly, all the way around. Few families can afford that with the rising prices of everything.

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