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Discussion Topic:
Highway driving speeds for a '48 239 c.i.
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carducci7 |
03-24-2016 @ 6:15 AM
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Joined: Jul 2015
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I have a '48 Ford Super Deluxe purchased 8 months ago and I have been able to motor along on divided highways and even the Interstate at pretty much highway speeds, i.e., 60-65. An acquaintance of mine disputes that saying that 50-55 is about all that engine and conventional 3 speed tranny is capable of doing because in 1948 before the Interstates, cars were not built to go at speeds we're used to today. I'd love to have input from anyone who has relevant info on this. Thanks, Tom
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TomO |
03-24-2016 @ 6:34 AM
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Your experience is similar to the experience of most owners of cars from the late 30's and 40's. The cars will go that fast and even faster, but you will have to decide on your own if that is a good idea.
Tom
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cliftford |
03-24-2016 @ 6:42 AM
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From my experience,with 3.78 rear axle it should cruise quite nicely at 60.Faster than that for extended periods will shorten the life of the engine.I would check the speed with a GPS. These old speedometers are often not too accurate.
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juergen |
03-24-2016 @ 7:11 AM
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Back in the 80s, when we were in our 40s, our car club would travel to Florida and Colorado for National meets from Iowa. Our leader, the owner of Early Ford V8 Sales in Walker, would travel at 75-80 on the interstates. No problems for all of us. As we got older, the speeds decreased to the speed limit and the longest distance was the midwest Spring Fling. Now that we are old, we don't travel long distances. The Fords can do it, especially with the newer lubricants available today. The major limitation is stopping distance, especially in traffic when the new cars cut in because they see a 2 car length opening. Interstate inner city traffic is the main limitation.
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len47merc |
03-24-2016 @ 7:45 AM
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TomO & cliftford are correct and on the mark. I have a '47 59AB with a 3.78 rear. My max comfortable cruising speed per GPS is 60 mph which reads 55-56 mph on the speedo. The car can reach 98 mph (or maybe faster, who knows - but WHY?), and can cruise at 65-70; BUT, even a suspension in like-new, top-notch condition of this era was, IMHO, not designed for speeds much beyond 55-60 and any quick, evasive maneuvers above those speeds I do not perceive will go well at all for the driver/owner. Plus, with a 3.78 at 55-60 mph the motor is turning 2,500 rpm which is in the designed range for optimum/maximum torque. Engine compartment noise becomes troublesome personally above this rpm & speed as well. And I agree above these speeds for extended run periods you will shorten the life of your engine, possibly significantly.
Steve
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kubes40 |
03-24-2016 @ 9:33 AM
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The cars I've had with the 59 series engines and 3:78 ratio differential traveled very comfortably at 60 - 65 as long as I so desired. And okay, so the engine might wear just a bit quicker than at speeds of around 55... so what? It won't wear so quickly as to cause an issue in nearly most all of our lifetimes.
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trjford8 |
03-24-2016 @ 5:58 PM
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Check your rear end ratio. You may have 3.54s. That ratio is found every so often in the 46-48 cars. A 46 I once owned had 3.54s and easily ran at 70. Look on the bottom rib of the rear end housing. You will find two numbers. Divide the small number into the big one and it will give you the ratio. Hopefully the ring and pinion are original to the housing.
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len47merc |
03-25-2016 @ 7:24 AM
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Agree also with Mike and trjford8 - can also cruise @ 60-65 mph even with the 3.78, just do not feel it is as safe or comfortable to drive the '47 above 60, especially on the original style bias plys.
Steve
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jwitt |
03-25-2016 @ 8:34 AM
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Back in the day when I was racing, we used a rule of thumb that the engine wear rate went up as the square of the RPM. I don't know where that rule originated, but of course the race engines were generally running near full load too. I've seen some SAE data that indicates the wear rate goes up temporarily when the RPM changes or the load changes, then stabilizes at a lower rate if the RPM/load are held constant. So don't go revving that engine to impress the bystanders!! Personally I like to run where the car feels happy and I feel happy. John
Houston, Tranquility Base here, the Eagle has landed.
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Old Henry |
03-25-2016 @ 6:08 PM
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I cruise all day on my road trips between 60 and 65 mph on bias ply tires without any problems.
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