>I make
>the following request:
> Would you please tell me the RPM's at 55, 65, and 70 MPH?
> I would really appreciate it!
>
>Thanks and God Bless,
>-Vince
>San Antonio, Texas
As mentioned, tire size will affect the ratio of RPMs to speed.
On my 71BGT, I installed an OD transmission several years ago. I then found
my speedo was not reading correctly. But I had a spare!
I calculated that one speedo was reading low about 5 or 10% but the needle
wavered. The stable speedo read high about 27%. I took the stable one and
figured out exactly what 60 mph was by cruising on the highway. As soon as
I hit the speed that took 60 seconds to go from one mile marker to the next
I knew I was going 60 mph. Then, I could determine the ratio of my speedo
reading to the right speed. I could also determine the rpm to mph ratio.
After I determined 60 mph, I took some scotch tape and marked 50, 60, and
70 mph marks on my speedo. So for a number of years, I used that to tell
what speed I was going - and I only got two speeding tickets over the five
to seven years I used this method (in each case I was well over 70 though).
Fortunately, the tape was removable because now I don't care since we have
no daytime speed limits here (Montana), but then my speedo has not worked
for the past week. Maybe I'll work on it this weekend.
David
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