I'm replacing idiot lights with guages and am having some difficulty getting the tach to work. I have been told that the tach filter was not needed...it just help filter radio noise. But since the guage isn't working, I've begun to wonder if this was correct? Can you shed some light on this?

what year of elko are you hooking a tach up to? what kind of tach are you using? do you have HEI distributor or what? I have a 78 with a HEI distributor, used a Sun Pro 3 3/8" tach and the green wire hooks up to the distributor part that says TACH and after all my power and light wires were connected it worked like a charm. maybe its another problem that other people can pin point out.

I have been told that the tach filter was not needed...it just help filter radio noise.
That's correct. The tachometer will work whether you have a filter or not. When my 86 MCSS tachometer stopped working I just bypassed the filter to get it working again.

Hello: Your tach should work without the filter, although the filter should be used if the filter is operational. You should be able to check it with an ohm meter to see if it is open or shorted or out of specs. The filter is basically a 3 wire do-dad One of the wires is the metal mounting tab. If you measure from the tab to either wire coming out of the ends you should read an OPEN, if you read anything the filter is bad. From one wire to the other wire you should read 15,600 ohms +- 5%. If you do not read this the filter is bad. The filter is an RC network consisting of a coaxial capacitor and 2 resistors. One resistor is 5,600 ohms in series with a 10,000 ohm resistor. If your filter does not check as i have described it is bad
good luck
Darryl...