MSefi.com read only forum (Jan.15,2018)

I'm going to put MS2 with board 3.57 in a 68 Olds with the factory tach, will it work properly or will i have to make some upgrade to a newer type tach internals?? THX

A bit more info would be helpful

If you are keeping the stock ignition system OR the tach is fed from the alternator W terminal (which I think is unlikely on a '68 ) then you are OK.

IF you have gone for a different ignition system, you need to know how the tach gets it's feed. If it is triggered from the coil -ve terminal, you can use diodes from the coil pack -ve feeds (one feed per coil on coil packs) to fool the tacho. Here's a picture for a 4-coil wasted spark ( V8 ) setup:

Hi,

I am asking for my RV8 which has an alternator "W" - fed tach input as you know, Fridge ;)

I do have an output from Megasquirt-2 which supplies a tach-signal. Is there any chance for me to drive the tachometer with it ? That would be my favourite - the wire is just there, without any use at the moment and I know where to catch the wire that goes to the tachometer in the binnacle.

If not --- I´m asking because my alternator seems to be faulty in letting the RPM-gauge move only for a short burst when cranking begins --- should I think about taking a signal from the EDIS-coils ? I have no idea what kind of signal the tach expects, respectively it wants a frequency signal but what voltage (12V probably) and what "Hz" I cannot guess (must be dependent on the pulley-ratio of the alternator.

Can you guide me to one solution or the other ?

(Well the alternator is nearly new, 120A type, charging happily and was cheap due to that fault. But it kept me on the road so I accepted the missing alternator>tach signal. It´s a Bosch alternator and I have no real idea of how to disassemble it further than removing the black lplastic cap of it´s rear. If it were an old Lucas alt. I think I could inspect the "W"-connection and try to repair something.