How to calibrate tachometer?

[bob26]

Any ideas how I could work out or estimate RPM to calibrate the new rev counter I have fitted to my Beta 14hp two cylinder diesel - or will I have to buy a handheld optical tachometer for this?

It's the sort that runs off the alternator signal wire.

 

[earlybird]

If you set it at 800 rpm with the engine on tick-over, you won't be far out

 

[sailorman]

Any ideas how I could work out or estimate RPM to calibrate the new rev counter I have fitted to my Beta 14hp two cylinder diesel - or will I have to buy a handheld optical tachometer for this?

It's the sort that runs off the alternator signal wire.

My Nanni ( Kubota based ) has a code to set-up the Tach there is a small button on the back of the Tach (depressed with a small dia tool "x" times) to tell the Tach wot its fitted to. the sender wire comes from the Alternator.
phone Beta they will tell you

 

[VicS]

will I have to buy a handheld optical tachometer for this

I have couple of mechanical ones. I think one was my father's and the other my grandfather's. Doesn't everybody have this sort of thing kicking around?

Oh and a rev counter. Just hold it on the shaft for a minute and see how many revs it counts!

Optical tachometer

 

[Strathglass]

Any ideas how I could work out or estimate RPM to calibrate the new rev counter I have fitted to my Beta 14hp two cylinder diesel - or will I have to buy a handheld optical tachometer for this?

It's the sort that runs off the alternator signal wire.

I had that problem when I replaced a faulty tacho.

The original one had a multi position switch which just needed set up to the correct position.

The new one has a rotary adjuster which has to be set match the reading to the engine speed.

I wanted to be certain of my engine revs in order to keep my gearbox and stern drive below their permitted maximum revs.

I ended up buying a non contact laser digital rev counter from ebay in China. It cost less than £10 including carrage (item no 370127091793)

I used this to set up the new rev counter with no problems - It is quite a handy little thing.

Iain

 

[impact30]

If you know what the max RPM of your engine is, warm up....full throttle in neutral...then set tacho.
I did this and tick over revs indicate that it is correct. it doesn't take long and will do no harm to your engine.

 

[dunmor]

where are you in sussex, i may be able to lend you mine.

 

[Refueler]

Any ideas how I could work out or estimate RPM to calibrate the new rev counter I have fitted to my Beta 14hp two cylinder diesel - or will I have to buy a handheld optical tachometer for this?

It's the sort that runs off the alternator signal wire.

Ebay have many chinese handheld tachos for very small money ... I bought one for about a tenner incl. postage. Works a treat ... is pocket sized ... can be used to see shaft rpm, engine rpm ... checking car / you name it ...

http://cgi.ebay.co.uk/Digital-Laser..._Measurement_Equipment_ET?hash=item5d26b70f10

Why guess or fluff about when you can have a digital hand job tell you exact.

 

[bob26]

Many thanks for all suggestions and help and for the generous offers of loans of handheld tachos. I have taken plunge and ordered a cheapo handheld of my own. I couldn't see how I would need it more than once but then I recalled the many times I've used my digital calipers which I never foresaw until I was given a pair.

 

[Refueler]

Many thanks for all suggestions and help and for the generous offers of loans of handheld tachos. I have taken plunge and ordered a cheapo handheld of my own. I couldn't see how I would need it more than once but then I recalled the many times I've used my digital calipers which I never foresaw until I was given a pair.

First thing I did when I got mine was to start measuring all the whirly things around me !! Amazed at speeds of some ! Kept me amused for ages ...

Tip ... if you don't want to unbalance a light object by affixing tape ... use silver paint or any paint that reflects the laser / LED light. Or if the object is ie a flywheel, propshaft that tape would have trouble staying stuck to ...

 

[fisherman]

Many thanks for all suggestions and help and for the generous offers of loans of handheld tachos. I have taken plunge and ordered a cheapo handheld of my own. I couldn't see how I would need it more than once but then I recalled the many times I've used my digital calipers which I never foresaw until I was given a pair.

Oh come on, where's the H Robinson inventiveness gone? Get a bike wheel, with spindle, paint a mark on it, let it run on the shaft or other reckonable revolving component, count against the clock, do the maths. Or one of those highway trundle wheels.

 

[status]

Tip ... if you don't want to unbalance a light object by affixing tape ... use silver paint or any paint that reflects the laser / LED light. Or if the object is ie a flywheel, propshaft that tape would have trouble staying stuck to ...

Tip-pex (other correction fluids are avaliable) - Works for me!

Stuart

 

[bob26]

Oh come on, where's the H Robinson inventiveness gone? Get a bike wheel, with spindle, paint a mark on it, let it run on the shaft or other reckonable revolving component, count against the clock, do the maths. Or one of those highway trundle wheels.

Yes, sad lack of imagination I'm afraid Fisherman. I'm shamed by your post. I do have a bicycle computer that I was tempted to have a go with - and a digital multimeter with a frequency setting that I could have attached to the signal wire coming out of the alternator but by the time I'd measured the diameters and calculated the ratios of the pulleys and "done the maths" I'd have no more confidence in the revcounter readings than just setting it at tickover and/or full blast...and might as well not have bothered to have one. Of course, the precise digital readings from a cheap tacho may be no more accurate in fact but I'm hoping the illusion of accuracy will provide more comfort. Just why I do need a rev counter escapes me for the moment. I bought it 5 years ago and though I have survived without it, having paid good money for it (though admittedly not very much - Beaulieu Jumble special or e-bay I expect) it seems perverse to have it on board without even connecting it up.