The Ford Barn - RPm on open road

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gwmartin55

08-21-2020 09:49 PM

RPm on open road

What is preferred rpm when on open road? Fresh 37, 21 stud engine 3:55 gears . Choice of tires open. Shift at 25 and 38 mph. Expect lots of open road driving. Don’t want to over rev it on long trips.

JSeery

08-21-2020 10:02 PM

Re: RPm on open road

It is somewhat a matter of personal preference. 2500 isn't a bad starting point.

GB SISSON

08-21-2020 10:14 PM

Re: RPm on open road

Do you have a tach?

CA Victoria

08-22-2020 03:44 AM

Re: RPm on open road

2 Attachment(s)

Here is a calculator to give you an idea where you are with your car RPM.
600-16 bias tires are about 28-28.5” tall.
With 3.55 gears you will turn abt. 2350 @ 55, your engine should be happy.

The Columbia chart gives a close comparison too.

http://www.csgnetwork.com/multirpmcalc.html

34PKUP

08-22-2020 05:28 AM

Re: RPm on open road

Quote:

Originally Posted by CA Victoria (Post 1922730)

The Columbia chart gives a close comparison too.

Wonder if I am the only one who can't read the Columbia chart as posted?

glennpm

08-22-2020 06:56 AM

Re: RPm on open road

1 Attachment(s)

I modified my chart for your 3.55 and 28.5" tall rear tires.

JSeery

08-22-2020 08:41 AM

Re: RPm on open road

I think it is easier to just run the numbers.

RPM = (Axle Ratio x MPH x 336) ÷ (Tire Dia)

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