Re: Figuring RPMs....

[tsm1@domain.elided (Tom Mandera)]

>Hi All,
>
>Since my '58 A-102 does not have a Tachometer, I thought I could figure
>But after doing so, the RPMs seem sort of low.  Can you all check my math....
>MPH/Gear 1 2 3 R
>60 8067 4400 2736 10069

Jeff,

It all looks OK.  I did this calculation for a bunch of possibilities, and
made a web page.. see http://www.tmcom.com/~tsm1/scout/faq/index.html  and
look under the Tire Size / Gearing / RPM.

The equation I used is:

Tire Diameter / 168 * RPM / Gear Ratio = MPH

I worked it a little differently than you did.  I grabbed the Eq. from the
Edelbrock page.

From my chart, I listed off 2500rpm, 3000rpm, and 3800rpm.

w/ 3.73s and 29" tires, that comes out to - 57.8mph, 69.4mph, and 87.9mph.

So 2500rpm - 57.8mph.  You said 60mph = 2736, which is right.

I built the chart so I could quickly see what tires size and gear ratio
would give me what kind of cruising speeds..

I think I'll add the 2000rpm line soon.. since I think that's the point max
fuel economy is realized on the highway...

-Tom