6 cylinder tach question

[pofo]

I have swapped in an S52 and runs perfect, just finishing up the small parts. I know that the stock M10 tach will not work so I bought a green strip 323i tach. Before I did the swap the rmp where high around 4k, now I am not getting a reading from the 323i tach. Is the single different from the m10 to m20? How can I bench test the tach?

[pofo]

Here are the two tachometer that I have swapped.

[GDAus]

Ummm .... the M10~M20 are both old style coil and distributor ignition systems that transitioned from points to electronic switching. The tachos for them just "read" the >12 volt switching pulses across the coil.
From memory the M50 series engines were distributorless with a Coil On Plug ignition system driven by the engine's ECU.
So the output to the tacho would be a digital, ie 0 - 5 volt pulse train. So you are going to need some sort of driver circuit to convert that into a form the old style tachos' can read. There are a variety of ways to do this. The people who have done the full Megasquirt conversion could probably help here?

Cheers

[pofo]

That's what i've come to find out digging down the rabbit hole.

https://www.summitracing.com/parts/a...FRCBswodmGwK0Q

I've found this but and 90% sure this is what I will need but not a 100% sure if it will output 12 volts or the 5 volts.

[Tom D]

I run the orginal tach with motronic, have done so with several M42 swaps. I've heard that motometer doesn't play nice with motronic, all my swaps were done with VDO gauges.

[pofo]

I run the orginal tach with motronic, have done so with several M42 swaps. I've heard that motometer doesn't play nice with motronic, all my swaps were done with VDO gauges.

The only issue with the stock gauge is that it's reading to high. I would/can swap the faces if I can figure out how to change the resistance for a 6 cylinder.