Just a comment,
Check me out on this, but the tachometer is an electronic gauge and
is subject to reading variations due to poor electrical connections or
bad grounds. The speedometer on the other hand is a mechanically
driven device running off of the gearing in the transmission. The speedo
should read correctly if there isn't a problem with the drive cable, lack
of lubrication, frayed wire in the cable etc. that would cause the cable
to bind in its rotation, which would usually cause the speedo to 'jump'
around. If the speedo is reading smoothly, and hasn't had any previously
noted problems, there should be a direct relationship between the
engine RPM and indicated speed ( about 18 MPH/1000RPM) in forth
gear (no O/D).
The tach. on the other hand could vary easily start giving suspect
readings due to corrosion on the connections to the tach., or even poor
grounding in the distributor ( but that would probably also tend to give
the engine a miss I would think..).
If it was me I would check and clean all the connections to the tach.
and coil/dizzy and see if that doesn't clean-up the problem.
(Incidently, I have a tach. that periodically gives 'flaky' readings that
I
have to do the same thing too....)
Harlan.
-----Original Message-----
From: Andrew Errington <ame@synaptics.com>
To: mgs@autox.team.net <mgs@autox.team.net>
Date: Wednesday, September 16, 1998 5:52 PM
Subject: RE: RPMs
>Don't forget, in 4th gear (no OD) then tach needle and speedo needle should
>be at the same angle.
>
>Andy
>
>
|