hi, i have just got a new tacho, just a 120y standard one, for in my 120y. I have an L20B, when i used to have the A12, the tacho work fine, and was accurate, it moved smoothly. But now, ever since I got the L20B, it worked for a while (2 Weeks) and then just went spastic, like from 0 to 8000 back and forth. while it did work, it was still a bit wavery, not smooth like with the a12, sort of when back and forth by about 500 or 1000 rpm. My new one does this too, i would like to know if anyone has had this problem and how the hell to fix it. Thanks

that sounds like an electricky problem. Perhaps a wire is not connected properly?? if any of the 3 are loose or dodgy, then you would get the intermittant signal making the needle jump around, but about it hitting 8000, well unless you car does these revs, then i would point the finger at the pcb on the back of the taco. Take it to a instrument shop and have them test it if you are sure the wires are all in good nick.

Is it the stock B210 tachometer? Those use a wire loop, pull the wires off and put them back on (maybe it is a bad connection).

Also, does the L20B have a points distributor like the A12 engine did? If it has electronic ignitiion or aftermarket high-energy maybe that's not compatibile with a factory B210 tachometer...?

hmm thanks, but there isnt any loose connection, just had a look which meant dismatleing the dash, this loop thing, what is it? is it that one wire that doenst have a connector, it wraps around the screw?

That one that wraps around the screw is the earth I think, I am sure dd will correct me otherwise.

I could be that the PCB has dry joints. Is the tacho a new new one, or a new old one??

nah its another old one...

i had the same issue when trying to run a factory 1200 coupe tacho with my 12a engine (electronic distributor). it jumped about all over the place.

im with dd on this, it may be the problem if you have an electronic distributor in the l20b. do you?

my fix was going aftermarket.

hmm okay, im not sure what dissy i have, it was whatever is on the motor. Any suggestions for a after market tacho that would fit in that sqaure hole in the 120y dash?

electric dizzy should not make a difference. It sounds like a bad earth. ensure your eart connection is less than 1 ohm.

I'd go with bad earth too. Had the same issue once. Suggest running a length of wire from the tacho earth wire direct to the negative battery pole and see what it does then as another way to check.