Anyone know what the peak RPM of a flathead is, in general. Also, the top RPM of a built-up one? Reason I am curious is that I have a 6 V SW tach and wonder if the top reading of 4500 pulls in all the flatheads. Thanks in advance. Perry
A stock flatty will see a few trips to 4000+ before becoming terminally ill. A race engine is a whole 'nother story though. If I remember correctly the Poteet & Main Flat Fire's flatty was wringing out 10,500. Sent using the NEW Droid HAMB app from atop my toilet.
A friend of mine had a stock V8 flathead in a '51 Ford. The motor was low mileage (around 20K as I remember). When he ran it hard though the gears with a 3 speed manual the motor seemed to peak around 3500 rpm on the tach, and he shifted at 4000 rpm. Hope that helps some. --- Steve ---
The factory hp ratings were at 3800 for a stocker. I know of two with stock bore and stroke but blueprinted, full pressure, and many racing tricks that turn 6-7000.
When Im driving mine hard, I shift at 5500rpm. A well built engine will stay together and still pull.
I have a 5k Sun Football tach on my warmed up '40, but don't think it's ever pulled more than 3500. Your 4500 SW should be fine.
The flatmotor will rev a lot of RPMs unloaded in neutral, but it runs out of breath early on under load. It takes much port, block and head work to make any horsepower above 4,500 RPMs. jack vines
I remember yrs back a Hot Rod Mag article on a Flatty that was reverse flowed, and he was running at the Salt Flats. The tranny stuck in low and he ran it anyway, and it hit 10000 + RPM. Don't remember to much more as it was many yrs ago. Iceman
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