Highway speed rpm

AnthonyG said:
JSeery

JSeery, true, was just getting the # off of the spec. sheet I posted from Vanpelt, but I did find several other published spec. charts indicating close to the same but chose Vanpelt as he is well respected on FB.
Here's another, http://www.secondchancegarage.com/public/406.cfm. Haven't been able yet to find an actual torque curve test chart. It would be interesting to see if you have or know of one?
Click to expand...

I was interested also, that's why I asked about a torque curve. Ford was known to be overrating their torque and hp values in these years. Manufacturers do rate engines setting on a test stand stripped of all accessories and tuned the best possible, but still it seems no one else can come close to the numbers Ford published. Seems a little strange they were that far off. I know in later years they were know to underrate their engines for other reasons. Got to love marketing. I use VanPelt as the "go to" for a lot of information, however I have also found a lot of errors on their site. So good source, but don't take everything posted there as the gospel!
 
Kevin,

To answer your question, in my opinion you can't hurt a sound flathead engine by running it all day, every day at modern freeway speeds, regardless of the rear end ratio or tire size. By "sound" of course, I mean it's in good mechanical condition, runs properly, doesn't ping at speed, and doesn't overheat. If it suffers from one or more of these conditions, then the advice would, necessarily, be different. These are very tough engines and were designed to be run hard, as long as they were in good tune and condition. I do agree with the prior posts, however, that flatheads do seem to have a "sweet spot" so far as cruising speed...usually somewhere around 60 - 65 mph...you know it when you hit it...they just sing along...they'll go faster, and you won't hurt them, but they're not as happy.
 
I have the original wide open throttle performance curves chart showing curves for mechanical efficiency, compression, torque, spark advance, and brake horsepower. Ford used the mechanical efficiency at 3000 rpm to achieve the advertised 95 horsepower. Engines were tested with generator and water pumps, but without fan or muffler. The true "sweet spot" is where horsepower and torque curves cross, That is just over 2100 rpm. Depending upon the gearing, that should fall in the 50-55 mph range.
 
Thank you for your comments! I bought the car in northern Illinois in July then the following weekend I drove it to Louisville Kentucky for the street rod nationals. It ran like a sewing machine at 60, but I felt that 65 just made too much noise, no knocks or clicking, just seemed a bit high strung. I drove it to Michigan last weekend and felt the same thing so when I got to Indiana I got off it and let the "jet set" butt heads fly by with fingers in the air... I think the "sweet spot" is the way to go...I just need a bit more confidence in my judgement... :-)
 
I didn't mean to be antagonistic, my apologies.

I find most flatheads run well up to around 2700 r.p.m.
My 53 sedan has the standard non-overdrive 3.92 ratio axle (I added the overdrive). With the 28 in tall tires I run up to 80 m.p.h. in overdrive comfortably.
 
supereal said:
I have the original wide open throttle performance curves chart showing curves for mechanical efficiency, compression, torque, spark advance, and brake horsepower. Ford used the mechanical efficiency at 3000 rpm to achieve the advertised 95 horsepower. Engines were tested with generator and water pumps, but without fan or muffler. The true "sweet spot" is where horsepower and torque curves cross, That is just over 2100 rpm. Depending upon the gearing, that should fall in the 50-55 mph range.
Click to expand...

The ONLY place torque and horsepower curves cross is at 5252 rpm.
 
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