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EFV-8 Club Forum / General Ford Discussion / Highway driving speeds for a '48 239 c.i.

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Posted By Discussion Topic: Highway driving speeds for a '48 239 c.i. -- page: 1 2     camsaure 03-31-2016 @ 10:45 AM reply profile send p.m. Member Posts: 51 Joined: May 2015 First off, I have owned my 39 Deluxe coupe since 1968, I was fairly young when I bought it for $235. The owners manual states "no breakin necessary you can drive up to 60 mph from the start, after that you can drive as fast as you desire"! Back then that was all I needed to see. I have to admit I drove the heck out of that car, but usually cruised 65 to 70. The engine did use a bit of oil so I took it apart at about 128 thousand miles. The engine was still in remarkably good condition, the guys in the machine shop were impressed. Engine is still std bore, valves were touched up and rods checked. I did grind the crank 010, but could have got buy if I could have found 001 oversize brgs. Car now has about 142 thousand miles on it. Didn't get used much for many years as I had to raise family etc. Are these cars as safe at freeway as modern cars? Of course not. But, back when I drove the car the most the speed limit was 65, and on roads that would make the anal govt bureaucrats these days scream. You just need to use a bit of common sense. I don't think my 39 would corner as well as a 40 and later with sway bars and track bars (this sort of shows up when driving in big cross winds) and there are stopping distances. I am now in the process of a complete rebuild and restoration and also installing a Columbia rear end that I got from a parts car I bought about 40 years ago. I still plan to drive some 70 to 75 mph on open uncrowded roads. carducci7 03-29-2016 @ 4:38 AM reply profile send p.m. Member Posts: 13 Joined: Jul 2015 Thanks to all of you who replied. I too am in the camp of the 60+ mph group and the other day I went out to a local show across the mountains here in Western North Carolina and on the uphill climbs, my '48 flattie ran like a charm at 60+ with no straining and no increase on the temperature gauge. Again, my thanks to all of you, Tom Old Henry 03-25-2016 @ 6:08 PM reply profile send p.m. Senior Posts: 738 Joined: Apr 2010 I cruise all day on my road trips between 60 and 65 mph on bias ply tires without any problems. jwitt 03-25-2016 @ 8:34 AM reply profile send p.m. Member Posts: 28 Joined: Mar 2016 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. len47merc 03-25-2016 @ 7:24 AM reply profile send p.m. Senior Posts: 1165 Joined: Oct 2013 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 trjford8 03-24-2016 @ 5:58 PM reply profile send p.m. Senior Posts: 4218 Joined: Oct 2009 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. kubes40 03-24-2016 @ 9:33 AM reply profile send p.m. Senior Posts: 3406 Joined: Oct 2009 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. len47merc 03-24-2016 @ 7:45 AM reply profile send p.m. Senior Posts: 1165 Joined: Oct 2013 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 juergen 03-24-2016 @ 7:11 AM reply profile send p.m. Member Posts: 258 Joined: Jan 2010 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. cliftford 03-24-2016 @ 6:42 AM reply profile send p.m. Senior Posts: 845 Joined: Jan 2014 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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