Thanks for the testimonial Jim! Glad it's working well for you.
Hi Pat...yes we do have a better mousetrap now for making a tach work with a mag.
The Autometer 9118/MSD 8132 (same device) don't work real well with points mags. The noise of solid core wires and big coils and such make them almost useless in a lot of situations.
We've been working on this for years! Instead of fighting the noise, our new unit actually uses noise. It has a pickup that tie-wraps to the high-tension coil wire or under the wire hold-down on the mag cap. The pickup is about the size of an ice cube and has a small hole in it for the tie-wrap to secure it.
The unit itself is enclosed in a billet aluminum box to keep all the noise out of it. It makes a great tach pulse signal from the noise that the mag emits on the secondary side.
The other big issue is that most tachs and shift lights pick up noise on their power and ground wires and even with a good signal, they freak out. So...our unit supplies clean, filtered power and ground to the tach device as well. The FIE tach pulse generator will power devices up to 1/2 amp (it has thermal protection on that) and keeps everything clean while supplying a square-wave pulse for the tach signal.
It works great with Super-Mags and Sprint mags as well as OXC and OAC Vertexes. On the internal coil Vertex, the pickup must be mounted on the side of the cap next to the channel for the coil wire. The internal coil Vertex requires a different (more sensitive) pickup as well.
The device must see 11.5-14 VDC on the input side. We recently had someone using an 18V cordless drill battery for power and it didn't like it a bit.
It's $150 for the unit, the pickup and 8' of shielded cable for use with the pickup. It is guaranteed to work for you or we'll refund your purchase price. I have not put it on our webstore yet but plan to in a week or so. The unit was tested quite a bit last summer and fall and they are ready to go. Picture below and a link to the instructions and schematics.
If you'd like to order one, FIE will pickup Priority Mail shipping for forum members in the USA during the month of July. Since it isn't on the webstore for the next week or so, you'll have to call and Stephanie can take your order: 541-990-2485 x0 She'll need to know if the mag is external or internal coil. Be sure to mention you're a forum member for free shipping.
Spud
For External coil mags:
http://fuelinjectionent.com/tech/FIE-TACH-SMAG-COMPLETE.pdfFor Internal coil mags:
http://fuelinjectionent.com/tech/FIE-TACH-VTX-COMPLETE.pdf