Cheap 4 in one tach? Thoughts?

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Piledriver
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Cheap 4 in one tach? Thoughts?

Post by Piledriver » Fri Jan 08, 2016 4:20 am

They sell decent looking but cheap 5" 4 in one tachs, with water, oil temps and oil pressure, some even come with the sensors. The water temp range might be high enough for a downstream CLT sensor in the hot used cooling airstream, properly shielded from outside air of course.

Might also be rigged to work with a cold compensated TC amp box with analog out, scaled appropriately.
(make rescaled face stick on for appropriate range, the meter will be ~linear)
this could be done for oil and water temp for a L&R CHT if desired cheap & easy, and calibratable.

Thinking a custom dash with one of these next to a T1 speedo.

The only thing horrifically wrong about them is they all read to 11K RPM.
I;m thinking make a new scale or face stick on and setting them to 6 cylinder mode would be a plan.
(top end would be 7326 RPM)

http://www.ebay.com/itm/100-Brand-New-5 ... tS&vxp=mtr
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

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Marc
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Re: Cheap 4 in one tach? Thoughts?

Post by Marc » Fri Jan 08, 2016 5:37 am

Looks like it's the same as this one on Amazon:

http://www.amazon.com/docooler%C2%AE-Ta ... op?ie=UTF8

There are reviews there - seems to be as good as folks expected for $50. Recurring complaints about re-boxed returned merchandise from this seller, and everyone agrees that the LED backlight is too bright when run off straight 12V.

You might find it challenging to get the bezel off to re-label the dial - I'd expect to find it crimped on with no easy way to remove it intact...so make sure the thing's gonna work and not need to be returned before you start tampering with it. I have a Chinese 8 grand tach on my trike and it's fussy (reads significantly different with points than it does with Pertronix) ...if you're going to need to add a tach sender to make it accurate that'll add another $50 to the cost.

As for a use for the "water" temp... if you have an external cooler and/or filter it might be worthwhile to monitor oil temp at two different places. Or maybe you could hook up an ohmmeter to the sender and bring it to a boil to see what its resistance range is. You might be able to find a sender that'll have those ohm values at a higher temperature range. Could be as accurate for head temp as the VDO gauges are ;)
Last edited by Marc on Fri Jan 08, 2016 5:46 am, edited 1 time in total.

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Re: Cheap 4 in one tach? Thoughts?

Post by Piledriver » Fri Jan 08, 2016 5:45 am

I'm already laying out a 2 channel TC amp board with scalable analog outs :twisted:

For 50 something with sensors if it works OK, its a bonus.
If not working reasonably well or borken, ebay/paypal provide recourse.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

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Re: Cheap 4 in one tach? Thoughts?

Post by Marc » Fri Jan 08, 2016 5:48 am

Piledriver wrote:I'm already laying out a 2 channel TC amp board with scalable analog outs :twisted:
Cool. I might be in the market for one come spring.

My wife's got an Amazon Prime account and they're super good at handling returns for us...they should treat us well, considering how much she spends there :)

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