The Ford Barn - View Single Post - What Defines Over-Revving The Model A's Engine

Bob Bidonde · 05-09-2020, 09:13 AM

What defines over-revving the Model A's engine? What is its redline RPM, the speed a Model A's engine can operate without damage?

Ford advertised the Model A's engine to make 128 ft-lbs torque @ 1000 RPM, and 40.5 HP @ 2000 RPM. At 2800 RPM, Ford rates the HP at 40.9, so the engine does little over 2000 RPM. At 1000 RPM where the engine develops its maximum torque of 128 ft-lbs, the road speed is about 25 MPH in 3rd gear with 3.78:1 gears and 4.75x19 tires.

With 3.78:1 gears and 4.75x19 tires, each 5 MPH requires 214 RPM of the engine in 3rd gear. So at 65 MPH, a stock engine is running at 2785 RPM and 2999 RPM at 70 MPH.

05-09-2020, 09:13 AM	#1
Bob Bidonde Senior Member Join Date: May 2010 Location: Long Island, NY Posts: 3,463	What Defines Over-Revving The Model A's Engine What defines over-revving the Model A's engine? What is its redline RPM, the speed a Model A's engine can operate without damage? Ford advertised the Model A's engine to make 128 ft-lbs torque @ 1000 RPM, and 40.5 HP @ 2000 RPM. At 2800 RPM, Ford rates the HP at 40.9, so the engine does little over 2000 RPM. At 1000 RPM where the engine develops its maximum torque of 128 ft-lbs, the road speed is about 25 MPH in 3rd gear with 3.78:1 gears and 4.75x19 tires. With 3.78:1 gears and 4.75x19 tires, each 5 MPH requires 214 RPM of the engine in 3rd gear. So at 65 MPH, a stock engine is running at 2785 RPM and 2999 RPM at 70 MPH. __________________ Bob Bidonde Last edited by Bob Bidonde; 05-09-2020 at 09:14 AM. Reason: Formatting space between paragraphs