[Axcella]

So, what options does that leave for solving the problem. more

[Kaporen]

Commercial braided shielding is available at good electronic stores and can be used to shroud the magneto signal converter, the tachometer, and its wires. As a temporary makeshift solution, even a simple aluminum foil shield will help suppress the radiation & noise. In extreme cases, shrouding the ignition wires themselves in grounded braiding may be required to eliminate the problem.

[JasonStarr]

However, if you absolutely have to have an electrical tachometer, because you are using it as a memory device or must have it because you are using it in conjunction with other electronic equipment that sets shift points etcetera, then you are going to have to shield the magneto signal converter (or relocate it), the tachometer, and, perhaps most importantly, all the wires going to and from them, from the electronic field created by the magneto and the solid core ignition wires. This can be accomplished by bundling the wires, where possible, and routing them though shielded conduit and then grounding the conduit. In this way the electromagnetism is carried to ground and eliminated as a source of trouble.

[Corazon20]

Well, first of all, you could of course eliminate the problem by using a mechanical tachometer. Mechanical tachometers are driven by a cable, which attaches to the body of the magneto. If you have a Vertex or Mallory magneto without the tachometer drive, Don Zig Magnetos can add one to your magneto so that you can use a mechanical tach.

[davidsoul434]

While i'm not sure if there are mechanical tachometers like speedometers electronic tachometers are quite simple. more

[Manjago]

Those pulses were, like in the GM HEI, generated by the ignition module from input of the pick up coil in the distributor. In these systems the timing is controlled an entirely in analog fashion. Fly weights and a vacuum advance control the timing in the distributor.

[bidcoin]

Electronic ignitions turn the ignition coil on and off in pulses to create the spark. These pulses directly correlate to how fast the engine is turning. For example a V8 will have four pulses per revolution. These pulses are converted to a voltage with a frequency to voltage converter. There are discrete circuits or stand alone chips that can preform this action. For example GM HEI ignitions commonly tie into the signal wire to the ignition coil to get the RPM reading.

[liamwilson1980]

As ignition systems became more complex the pick up coil was replaced by a crankshaft position sensor and the fly weights / vacuum advance were replaced by a computer. Eventually instead of getting the pulses from the coil the signal came directly from the computer. Even to this day the basic structure and operation of the physical needle in the dash has remain effectively the same, the difference being only where the signal comes from and how the signal arrives at the dash board.

[edwardgel]

Though this method delivers an accurate reading, installing a new tach can be confusing because of the different ignition systems used by the OEMs and the aftermarket.

[nixoid]

Tachometer installation can be as simple as connecting the tach’s sending wire to the negative side of the ignition coil, while other ignition systems feature a dedicated tach sending circuit.

[Dynotor]

In either case, installing the tachometer incorrectly can cause significant damage to both the tach and ignition system.

[Astro]

wikiHow is a “wiki,” similar to Wikipedia, which means that many of our articles are co-written by multiple authors. To create this article, volunteer authors worked to edit and improve it over time.

[Hiroe]

This article has been viewed 289,743 times.

[mattbrown75]

A tachometer is used to indicate the revolutions per minute (RPM) being performed by a car engine. Most cars with automatic transmissions are not equipped with a tachometer, since a tachometer is mostly used to indicate visually when it's time to shift gears. [1] X Research source If your car doesn't have one, it's a good way to keep an eye on your engine speed. See Step 1 for more information.