The Ford Barn - View Single Post

Dale Fairfax · 04-19-2011, 07:17 PM

Why does this question/subject keep reappearing without any one knowing what R.P.M. their engine is turning? That should be the limiting factor: A late '30s car with a 4.11 rear end will be buzzing the engine a lot harder than a car with a 3.78 gear at the same highway speed. The guy with the '49-'53 car with O.D. (even with a 4.11 or 4.27 gear) is only turning 70% of the R.P.M. his gear would normally dictate. A cruising speed which spins your engine no more than 3200 R.P.M is probably the max for comfort and reliability-regardless of the roadspeed.

04-19-2011, 07:17 PM	#19
Dale Fairfax Senior Member Join Date: May 2010 Location: Indianapolis Posts: 250	Re: Flathead highway speeds Why does this question/subject keep reappearing without any one knowing what R.P.M. their engine is turning? That should be the limiting factor: A late '30s car with a 4.11 rear end will be buzzing the engine a lot harder than a car with a 3.78 gear at the same highway speed. The guy with the '49-'53 car with O.D. (even with a 4.11 or 4.27 gear) is only turning 70% of the R.P.M. his gear would normally dictate. A cruising speed which spins your engine no more than 3200 R.P.M is probably the max for comfort and reliability-regardless of the roadspeed.