From: img width=12 height=12 border=0 src="http://opi.yahoo.com/online?u=dempsey2995&m=g&t=0" alt=""_REMOVE_111948_THIS_@yahoo.com
Thanks for the reply Duke. I will see if I can find a speedometer
shop to calibrate the tach for me. I could live with a tach reading
200 revs low at idle, but 500 revs high at idle is a bit much for me.
As far as my speedo. Im running 205/60/R-13 tires with an 5 Speed. I
have the speedo dead on by using the Stewart Warner adapter with
a .9705 gear ratio installed. I had to fabricate a speedo cable so I
could install the adapter in line. By installing the adapter to the
trans it made the speedo cable make a to tight of a turn as it was
hitting the transmission tunnel.
--- In <a href="/group/cosworthvegas/post?protectID=219233066105193209050199029077192253163098100009128121188190230091025019053061151110147">email@example.com</a>, doctorduke <<a href="/group/cosworthvegas/post?protectID=091233212180056219138097203245129208071">no_reply@y...</a>>
> CV tachs typically read high, particularly at the top end. A
> competent speedometer shop should be able to improve the tach
> calibration. They do this by removing the pointer and
> it on the pin. I had this done a few years ago. I knew my tach
> accurate at the bottom end, but became increasingly more optimistic
> revs increased. I asked the speedomenter shop to make it dead on
> 7000, which they did, and now it reads about 100 revs low in the
> range and 200 revs low at idle.
> Speedometer accuracy can also be improved for the shorter than OEM
> tires we typically have nowadays. Short tires cause a "gain error"
> that is a constant percentage throughout the range. A speedometer
> shop can change the magnetic flux of the head magnet to eliminate
> error, and any "offset error", which is a constant MPH error
> throughout the range can be corrected by repositioning the needle
> the pin. Such recalibration only affects the speedometer. The
> odometer cannot be corrected, so it will typically read 5 percent
> with 205/60R-13 tires, which roll about 920 revs per mile versus
> for the OEM BR70R-13 tires.
> Gain error in the tach cannot be corrected as with a speedometer.
> Only an offset error can be corrected by repositioning the pin.
> you have a accurate calibration table for the speedometer in its
> present state, you can evaluate it and instuct the shop to relocate
> the pin, and I suggest that you shoot for best accuracy at the top
> for obvious reasons.
[This is message #10710 by user img width=12 height=12 border=0 src="http://opi.yahoo.com/online?u=dempsey2995&m=g&t=0" alt="" on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas