dd, its coz hes got a stepper motor tacho so its alot more sensitive to noise apparently

just see how the resisters go mik, just keep putting in resistance till the tacho is smooth

DIS is the newer high-energy types that became popular in the 1990s. Most tachs won't work with them, and even timing lights need to be a newer type.

DIS type??

Which tachometer do you have? The stock 1200 ones work fine with Datsun/Nissan electronic distributor. I'm using mine with a 1990s Nissan A12 JDM distributor, which is the same type as found in late-1980s Nissan pulsar E-series in USA. The type without external electronic module.

Only if you are using a 1990s DIS type would I expect you'd possibly need a resistor.

I'd punt on the input (to the tach) being high impedance and hence tiny currents so don't worry about burning resistors, in any case they're a cheap fuse. My guess would be noise, if you can't look at the signal on an oscilliscope maybe try a low pass filter with a frequency set slightly above 2*(MaxRPM*2)/60, wiki low pass shows you all the background (http://en.wikipedia.org/wiki/Low-pass ... ectronic_low-pass_filters). The low pass would cut the high frequency coil oscillations out.

I'm sure someone's solved this before.

as my build thread had:

"the tacho is a pos according to piggy. it flickers around under load but settles when cruising at revs.

i like these guages and hope its either faulty guage but reading up on them, stepper guages either need a diode soldered in line to reduce the interferance in these old cars and get a clean signal or its a bad read off the coil.

it can also mean coil on the way out but piggy has a theory that the crappy wiring on the guages getting interference form the lpg stuff.

hope its an easy fix as the guages do look good and get ok reviews against a lot of other similar guages."

any one have any suggestions. i have 1k, 2k, 10k and 50k variable restistors to try but not sure what voltage or resistace should be from a bluebird elec dizzy signal to the coil and the the tacho trigger wire from the coil to the tacho?

i thought adding 2k near coil and 1k near tacho but i have a feeling they will heat up quick as there will be more load in the signal strength. but 10 or 50k might be too much resistance.