<VV> Non Working Stock Tachometer in a '66

[Jim Becker]

I thought the late model ('65-'66) tachs were all solid state, without a 
separate sending unit.  If not, I stand corrected on my earlier suggestion. 
My comments about voltage on one wire "The other connects to the distributor 
(should be hot with ignition on and points open)." would apply to the wire 
from the distributor to the sending unit.

Jim Becker

-----Original Message----- 
From: tony underwood via VirtualVairs
Sent: Tuesday, March 10, 2020 10:20 AM
To: Paul Siano ; Paul Siano via VirtualVairs
Subject: Re:  Non Working Stock Tachometer in a '66


> On March 9, 2020 at 3:35 PM Paul Siano via VirtualVairs 
> <virtualvairs at corvair.org> wrote:
>
>
> Needle doesn't move when starting and driving...but moves just a little 
> when turning the key off.
> Any suggestions about where I should start?
> Paul Siano


Maybe start under the hood.  If the tach is an earlier model year factory 
item for a '66, it will have a sending unit, usually mounted under the hood 
on the fender well.  It will have several wires attached to a terminal 
strip. Later tachs look the same but the electronics are internal.  The 
earlier tach is just a housing with a meter movement. The sending unit 
receives pulses from the distributor and converts them to a 'difference' DC 
voltage that moves the meter in the tach head unit.  The fact that the tach 
meter movement burps momentarily with the switch suggests the head unit is 
ok and maybe the sending unit as well, since it's sending Something to the 
head unit but it's not receiving pulses from the distributor.  Check the 
wiring to the distributor.

tony..