I like to run flathead V8s (and my 215 valve-in-head six) at about 2600 on the highway, maybe up to 2700 rpm. Below that you lug the engine, above that they tend to sound a bit wound out.
As an example, I am gathering the parts to change the rear axle in my 53 sedan with the factory overdrive from a 3.90 to a 4.10. Currently the overdrive is a bit too high geared except in very flat land.
Ford did a pretty good job of picking axle ratios when these vehicles were new. Higher speed ratios than 3.54 were not offered until 1951 and then only with automatic transmissions. Ratios around 3.00 only were offered with the introduction of big displacement high output (compared to a flathead) V8s in the late 50's.
Well I am back looking into changing the rear end in the yellow bird 50 F1. I have posted a want on craigslist for a 1957 to 1972 F100 Rear End with a 3:50 -3:54 Ratio. This is what the forum said fit and worked best. I do appreciate the help from everyone. Hopefully someone will have one. If anyone out there knows of one please let me know
Last edited by 50trucking; 08-16-2014 at 09:42 PM.
in F100's... '73-79 is wider than the '57-72 9" rears. You want the '57-72 9" only. (5x5.5 lug pattern, beware of car types with the 5x4.5) You can swap 3rd members with other 9" rears to get the desired gear ratio, on top of the aftermarket support it has.
Also, since I'm late to this thread, the early Dana 44's from the '50's, have a different spider gear spline count than the more modern Dana 44's, so AFAIK, not any gear ratio can be swapped in. You'd be stuck with the 3.92 or similar gearing from the 1950's.