Corsa tachometers and other possible solutions on horizon

[66vairguy]

I've been following the Vairtrix tachometer posts as I was going to make a kit, but I could not come close to the low Vairtrix price. So I shelved it.

Yesterday I got a call from Ray Sedman (he makes Corvair items and has been around for many years). Ray talked to me about the old tachometer meter issues, and about a steeper motor design. Like me he lost interest when Vairtrix came out. I'm not going to talk negative about the Vairtrix as I have not examined one, but Ray has examined one and feels he might be able to do better. We talked of steeper motor resolutions and acceleration formulas to avoid needle inertial damage to the motor gearbox, etc. I mentioned I used the GM stepper motor used before they went to the "cheaper" design. It was a very brilliant design by a company in Europe increasing resolution by 50% with only two coils. I mentioned the driver chips are UNOBTAINABLE, but I used an open source program I revised to drive the steeper motor properly since it is a popular stepper motor and easy to buy. The other issue is power management to deal with old car power systems vs. new microelectronics.

ANYWAY ---- due to my age and health I'm winding down from the hobby and I'm going to give Ray all my information. Not sure if he can come up with a cost effective alternative to the Varitrix, but no doubt it will be well done if he does. He is also investigating other Corsa tachometer ideas for repairing original units. So stand by. Don't toss out those old broken tachometers!!!!!!!!!!

[Scott H]

Thanks for the update and all your work. Ray is a smart guy. Very nice too. I'm sure he will continue your work.

[66vairguy]

Thanks for the update and all your work. Ray is a smart guy. Very nice too. I'm sure he will continue your work.

Your welcome, but I think my ideas will contribute to what Ray does instead of continuing my work. He has some good ideas that had not occurred to me. As with most successful projects --- the more folks involved the better the outcome IF they can all get along -

[caraholic4life]

Just a suggestion here.....

IF Ray takes on this potential project, could the stock CORSA Tachometer be refitted in such a way as it could also work correctly with eight cylinder signals? This might solve some issues the V8 Corvair enthusiasts face when attempting to maintain a uniform style with the gauges...

I have been considering buying an Autometer GPS Speedometer, Tachometer, Gas, Oil, and other matching gauges for my Kelmark car to the tune of about eleven hundred dollars....I have not pulled the trigger just yet though.

[cnicol]

Just a suggestion here.....

IF Ray takes on this potential project, could the stock CORSA Tachometer be refitted in such a way as it could also work correctly with eight cylinder signals? This might solve some issues the V8 Corvair enthusiasts face when attempting to maintain a uniform style with the gauges...

I have been considering buying an Autometer GPS Speedometer, Tachometer, Gas, Oil, and other matching gauges for my Kelmark car to the tune of about eleven hundred dollars....I have not pulled the trigger just yet though.

For my V8 Corvair, I was able to recalibrate my stock Corsa tachometer without changing any tachometer components. Accuracy is similar to what we get with a standard Corvair engine i.e. pretty close.

[66vairguy]

Just a suggestion here.....

IF Ray takes on this potential project, could the stock CORSA Tachometer be refitted in such a way as it could also work correctly with eight cylinder signals? This might solve some issues the V8 Corvair enthusiasts face when attempting to maintain a uniform style with the gauges...

I have been considering buying an Autometer GPS Speedometer, Tachometer, Gas, Oil, and other matching gauges for my Kelmark car to the tune of about eleven hundred dollars....I have not pulled the trigger just yet though.

For my V8 Corvair, I was able to recalibrate my stock Corsa tachometer without changing any tachometer components. Accuracy is similar to what we get with a standard Corvair engine i.e. pretty close.

Agree - While I have never tried it --- in theory the analog gain adjustment will do the trick (hole covered on back of tachometer). If the potentiometer range is too limited would you have to change a resistor, but as cnicol said he did not fine it necessary! The meter circuit filters pulses to a very small current. You change that with the gain and in "theory" the linear nature of the circuit will make the stock tachometer read accurately for an 8 cylinder (if it read accurately for the stock 6 cylinder).

With a digital step motor system you just add a decision switch to change the RPM to motor steps ratio calculation in the software.
With some tachometers you just flip switches for 3, 4, 5, 6, 8, 10, 12 cylinders - all software.

Easy to add a start up dwell measurement via software -- but kind of useless as points are not that common anymore, OR if using the MSD system that has has a separate tachometer trigger wire it WILL NOT GIVE AN ACCURATE DWELL as it is not the signal from the points, or to the coil.

[caraholic4life]

Back when I originally owned my Kelmark car, I did make an adjustment through the hole in the back of the housing and it did make a difference. Unfortunately I never thought it was accurate but I lived with it as it was for years.

I recall back then that most aftermarket tachometers had an ability to select 4-6-8 cylinder options and thought such an option could be incorporated in anything developed these days....I do appreciate the feedback posted.

[63Spyderd]

I recall back then that most aftermarket tachometers had an ability to select 4-6-8 cylinder options and thought such an option could be incorporated in anything developed these days....I do appreciate the feedback posted.

For those who decide to go the Vairtrix route, it is currently capable of 6 or 8 cylinder operation. It defaults to 6 cylinder. There is a pushbutton switch on the unit that can be used to program it before inserting in the dash. Code 41 is for 6 cylinder; Code 42 selects 8 cylinder. If you're interested, you can email Vairtrix at vairtrix@gmail.com and they can give you more detailed instructions.

[caraholic4life]

I recall back then that most aftermarket tachometers had an ability to select 4-6-8 cylinder options and thought such an option could be incorporated in anything developed these days....I do appreciate the feedback posted.

For those who decide to go the Vairtrix route, it is currently capable of 6 or 8 cylinder operation. It defaults to 6 cylinder. There is a pushbutton switch on the unit that can be used to program it before inserting in the dash. Code 41 is for 6 cylinder; Code 42 selects 8 cylinder. If you're interested, you can email Vairtrix at vairtrix@gmail.com and they can give you more detailed instructions.

Thanks, I appreciate that bit of information.