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Discussion Starter · #1 ·
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=200040847959&fromMakeTrack=true

Can you please help me? I've never fitted a rev-counter before, but I'm just about to get a 1914 motor fitted to my Beetle, so I thought I'd better keep an eye on the revs - especailly as the motor also needs running in.

I've spotted this on eBay. It seems pretty cheap - is it any good? Does anybody have any experience of this particular model?

Also, and please excuse my naivety, but how exactly do you connect the Tacho - is it to the coil/electronic ignition somehow?

Thanks in advance.
 

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Type R brand hmmmmmmmmmmm jumping on the Honda/RFast and the Furious craze with a flash name for a no name brand.

But at £30 all in - worth a try. I bought a new Autometer that failed after 3 years.

Your choice.

Wiring - dead easy:

the guage will need an earth and a live feed from the fuzebox - live on when ignition on, no permanent live.

it'll also take a live and neutral from the dash lighjts to give it some illumination - just jump onto the dash light circuit for a feed.

lastly it'll need a wire from the guage to the coil "-" or "1" - same spade on the coil as the dizzy thin (usually green) wire.

Make sure this lead can't rub on any sharp edges or else it'll grind thru the insulation in no time and short out the coil - engine won't run and you'll spend days trying to work out why.



Finally, some tachos are for 8 cyl, or 6 cyl or 4 cyl. This is done by having extra loops in the circuitry, which you can cut to reduse the number of cylinders it'll work on. The instructions will tell you which wires to cut on the back of the guage top get it to work for a 4 cyl car. make sure it is good for a 4 cyl car before you buy.
 

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Discussion Starter · #3 ·
Thanks MIB. Very helpful for me.

I'll give one a crack now.

It does seem a cash in on the Honda - I'm sure they'll have something to say.
 

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Seems like a superb price for a 5" gauge including a shift light. Won't be up to competition use, but will be ok for road use.

I notice the shift light has a red lens. ...Which is normally used to warn of oil pressure. Amber is usually the colour of a shift light.
I bought an inexpensive tach, and ended up making an amber lens for it.

Wiring should be easy if they follow the usual wiring colours (if they don't, or have changed them, don't blame me!). Most tachs use Red for a positive 12v feed when the ignition is on, Black for earth, White for illumination (when the lights are on), and green for the negative side of the coil. Check the instructions that come with it. Now all you have to do is find the right feed wires/circuits in your car.
 

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I took a chance on one of these last week - for some reason the same seller also has the same tach listed at £49.99, so make sure you get the £19.99 one.

It came within 2 working days and was new and sealed.

There is a switch on the back to select 4, 6 or 8 cylinders, and pretty detailed instructions.

The controls on the front let you set the point at which the light comes on, and also recall the highest revs you have hit since you last pressed 'reset'.

I have a question though - if you select the wrong number of cylinders for your engine, the revs will read wrongly, but which way? - Reason is, the gauge shows up to 11000+ revs, but my engine is only going to rev to around half of that, so could I set the tach to 8 cylinder and have it sweep twice as far as it should? - If it will work, I'd look into re-masking the numbers inside to match, which looks straight-forward as they appear to be printed on clear acitate over the 'carbon fibre' background, so an easy print onto OHP sheets on an inkjet. Obviously this won't work if selecting '8 cylinders' makes the needle sweep half as far as for 4 cylinders...
 

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Discussion Starter · #6 ·
Cheers all.

I noticed the £50 one too.

I'm buying the £20 one now though.
 

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swapped said:
I have a question though - if you select the wrong number of cylinders for your engine, the revs will read wrongly, but which way? - Reason is, the gauge shows up to 11000+ revs, but my engine is only going to rev to around half of that, so could I set the tach to 8 cylinder and have it sweep twice as far as it should? - If it will work, I'd look into re-masking the numbers inside to match, which looks straight-forward as they appear to be printed on clear acitate over the 'carbon fibre' background, so an easy print onto OHP sheets on an inkjet. Obviously this won't work if selecting '8 cylinders' makes the needle sweep half as far as for 4 cylinders...
Good question I have decided against a tacho in the past cos it has a scale upto 10,000rpm and you would only use half that but i dont know the answer - would be sweet but i have a feeling it works the other way and would read half as much
:)
 

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It'll redline a standard bug engine at 2000 rpm :D




8 cyl = equivalent to half ther speed/RPM


My speedo gpoes up to 130 mpoh, but I don't always use those figures :D What a daft excuse for not buying a tach.
 

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I've done a little reading-up, and it looks likely that the switch on the rear of the tach just adds resistance at different values, depending on the 4, 6, or 8 cyl selection. A 4-cyl setting will be twice the resistance of an 8, and 6-cyl will be equally between the two - what I need, then, is a resistance equal to the 4-cyl setting, applied to the signal wire.

On that basis, I will be investing £1.21 at Maplin to purchase a 1k-100k range potentiometer (like a hifi volume control), which I will insert before the tach, and twiddle until I get the reading I wish (calibrated to a standard, 4-cyl setting).

Then it's a matter of dismantling the tach and printing a replacement set of dial numbers (and perhaps add my own printed red-line), and I'll have an accurate rev counter that sweeps through the full range of the dial!

I'll report back later...
 

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Sarum said:
What a daft excuse for not buying a tach.
:moon:

the one i did get goes to 8k ;)

would still be cool to have FSD to 5 or 6K :cool:
 

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Discussion Starter · #11 ·
Mine arrived this morning. The girlfriend has just rung to moan becuase she thought it was yet another pair of trainers. When I told her it was a tacho she calmed down. Odd.
 
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