Tachometer Problem

[Bruce Plecan]

-----Original Message-----
From: The Thibodeaus <vettenuts at efortress.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Sunday, November 08, 1998 10:04 AM
Subject: Tachometer Problem

OK. let me quess, this is a 1983 Vickesberg Vombat?.

In general thou, when doing a "update" for ignition using mis matched
components can generate all kinds of problems, ie:
Low resistance coil, now places excessive current load on ignition module.
So operation is erratic, and possible failure.
New higher secondary voltage, allows faulty plug wire to fail.
Glazed Spark Plug now randonly misses.
GM HEI Large Cap Rotor now has burn thru.  (remove rotor, and inspect
insides, for fly turd specks of black under center post).

When doing an ignition upgrade, do it system wide.  Find out what others
recommend, and have used in simular applications with success.  By system,
I mean Spark Plugs, Cap, Rotor, Plug Wires, Coil, any module enhancements,
etc..

Vickersberg Vombat comment was Grumpy's idea.  His early morning humor,
can be rather dry.
Bruce



>My tachometer rises with engine speed up to about 3000 RPM and >then seems
to stop or randomly increase a while the engine is >accelerating fine.  I
have recently changed the coil to a MSD coil.  I >have heard of this
happening if you installed the MSD 6 ignition, >but I don't have one of
those.  I then re-installed the stock coil and >the problem goes away.  I
have noticed on occasion that the >tachometer seems to slow down past 4000
RPM with the stock >coil.  Any ideas?  I checked the service manual but it
>seems that if the tachometer works at all they say to replace the
>"Electronic Spark Timing Computer" whatever that is.  Is this the >module
in the distributor?  Thanks for any input.
>Bob T