Since Bryan mentioned the Spyida RVI > RVC conversion kit, I thought I'd mention my experiences with it.
I tried the Spiyda kit on my tach. Installing the kit was simple but I was not able to calibrate it, At first, there was some response to the sound files but not consistent enough to adjust the tach. After that, it was completely unresponsive. I emailed the tech guy at Spiyda and he was very attentive. After VERY extended back and forth, in frustration I checked continuity of all the connections. It was a silly thing to do since everything was clearly attached and competently soldered but I didn't know what else to do. I mentioned that to the Spiyda tech and he said that I had inadvertently ruined the Spiyda kit by doing that. He said he would send me another for free. That one never made it to me so he sent me a third kit, this time with tracking. I received that kit and installed it according to the directions and was still not able to calibrate the tach. This time was it completely unresponsive. I eventually I sent my tach to West Valley Instruments (
https://www.westvalleyinstruments.com/) and they converted my tach successfully. It is supposed to work with pretty much any type of ignition. I am happy with their service but it was much more expensive than the Spiyda kit.
I also have a friend who sent his tach to Spiyda and his tach worked for a short time before acting up.
I'm not bad-mouthing the Spiyda kit and I have absolutely no problem with their customer service. Their tech guy could not have been more helpful. I feel certain they can work because some people have had positive experiences with them. My advice would be to try the Spiyda kit first (without testing continuity!!) since it is very inexpensive and if it works, your conversion is very reasonably priced. Should you fail to get their Spiyda kit to work and you want to keep the stock Smiths tach, I'd recommend West Valley Instruments. Otherwise, you should purchase an RVC tach..
That's my 2ยข, YMMV, and I admit that I am no expert - especially with electronics so keep all of that in mind when reading this!
