Tachometer Wanted

[Nasher]

I need a Tacho that will work with my V6 2-Stroke Johnson 150HP VRO

Anything will do, although I'd rather a larger format than the small 52mm ones.

Need to know what revs the engines doing, then I'll also be looking for props.

Don't want to spend too much as I'm just trying to make the most of this engine until I splash out on a 200HP E-TECH in about a years time.

Thanks

Nasher.