Corvair Forum

hey hey....

on a 64 4 speed with a plain jane instrument panel, is there a pre wired point where one might make a connection for a tach .... without going all the way back to the coil?

Tachometers measure (count) the number of times that the ignition coil fires by counting the electrical pulses that occur when the points close (allowing the magnetic field in the coil primary to build as current flows) and when the coil discharges when the points open and the field collapses. The tachometer is calibrated based on the number of cylinders in the engine, and the pulses are translated into a meter deflection giving a reading in revolutions per minute. The only place to sense this is on the negative side of the ignition coil. There is no wiring shortcut — the tachometer sensing wire must be connected on the negative side of the ignition coil.

thx bbod....

wernt some of the wire harnessez pre wired for spyder tachs...?

was hoping there was a spot just for that on harness etc. to catch an unused wire/connection

nice thought even if not possible tho eh?

er-mine wrote:...wernt some of the wire harnessez pre wired for spyder tachs...?

was hoping there was a spot just for that on harness etc. to catch an unused wire/connection...

The 1962-1963 wiring schematics in the shop manual supplement did not show Spyder wiring at all. The special temperature gauge wiring and tachometer wiring was discussed somewhat in a separate diagram on an added page.

As shown below, the Spyder wiring (labeled "600 Only" on the schematic wiring diagram) was shown in the 1964 Shop Manual supplement. However, the tachometer connection was a separate brown wire (20 BRN) that was routed directly from the negative coil terminal. It is not shown as a part of the wiring harness. The temperature gauge thermistor wire was depicted as included in the Spyder wiring harness. Clark's Corvair Parts lists the Spyder harnesses separately from the regular harness, indicating that the added wires needed for the Spyder are not a part of the standard harness.

There is no indication that you will find a tachometer wire residing in the standard Corvair wiring harness. Apparently when it was needed for the Spyder it was a separate wire that was added along with the Spyder instrument panel.

Left-click each schematic image to enlarge for better viewing...

er-mine wrote:...is there a pre wired point where one might make a connection for a tach?

No.

Pull several new wires when you do the tach wire because later you might want to add an electronic oil pressure gauge, an engine kill wire for anti-theft, extra temp senders, etc.

KK.thanks guys

just didnt want to miis a nice opportunity to make a clean quick connection

since its spyder specific am outta luck. thanks for shortening the thinking path anyway!~