Rev Counter

[5thHorseman]

I have just a simple control panel and have been looking at rev counters.

Those for boats struck me as a bit expensive - fariah etc also I was looking for a digital read-out.

I could not find a digital rev counter for boats on the net but found this site for aircraft which are weatherproofed for open cockpits which seemed to fit the bill.

 

http://shop1.actinicexpress.co.uk/shops/pa...r_Smart_Singles

 

I wanted it to be surface mounted so as not to punch large hole in the bulkhead.

 

I found the gauge fitted inside a piece of 2.5" square black rainwater drainpipe, so I cut a foamex gasket which makes it a snug interference fit, a couple of angle pieces from an old meccano set pop riveted through the side of the drainpipe provided feet for screwing it into the bulkhead with a couple of ss self tappers, small grommeted hole to take the wires + & - supply plus wire from the alternator "w" terminal and job done

 

It is backlit and has a buit in hour meter plus a second 0 to 100 hours which I will use to monitor oil change timings.

 

[magnetman]

For slow engines (under 1,000rpm) it is possible to use a bicycle computer set to wheel circumference 1667mm and to km/h range, magnet on flywheel with sensor (reed switch) close to it. Every km/h on the display will be 10 rpm engine speed. Could put it on propshaft and double the result to get engine speed. Also gives running hours up to 12h for daily records.

[John Orentas]

Hy Horsey

 

Been staring at this add for a few years now, Rev counter for diesels 4000 rpm 'no sender required' God knows how it works.

 

http://www.force4.co.uk/ProductDetails/mcs...5e-8edc1eb153ba

[Timleech]

Hy Horsey

 

Been staring at this add for a few years now, Rev counter for diesels 4000 rpm 'no sender required' God knows how it works.

 

http://www.force4.co.uk/ProductDetails/mcs...5e-8edc1eb153ba

 

Maybe its the standard type which uses the alternator as a 'sender'?

 

Tim

[chris w]

Correct

[Big Steve]

I believe there are some out there that sense the engine ignition by vibration, and therefore the revs, but I've never seen one in the flesh.

[carlt]

I use the second hand on my watch. I like to tap my foot to the beat too. ta ta tum, ta ta tum, ta ta tum.

[John Orentas]

Many years ago there was a device on the market which was claimed to give a true calibration for mechanical rev-counters.. It comprised a very simple, small base unit onto which was attached a perpendicular thin, spring steel rod, with a spherical weight at the far end, a sliding poise weight could be slid along the rod which was engraved and calibrated in RPM.

 

The idea was that you set the engine at a steady speed, hold the gizmo firmly to the engine or petrol tank in the case of a motorbike, slide the poise weight up or down the flexible rod until the spherical end appeared static, then read off the engine speed.

 

Said to be an accurate though pretty useless bit of kit.

Edited November 18, 2007 by John Orentas

[Supermalc]

http://www.tinytach.com/tinytach/index.php

 

This is what you want. I've not actually seen one, but have heard good reports from several people who have it. Works from a sensor that is clipped onto an injector pipe, which detects the vibrations every time fuel is pumped to that injector.

 

Sometimes you have to move the clip to another part of the injector pipe, or a different one, and it is also an idea to check the calibration with a hand held mechanical rev counter.

 

But from what I've read, everyone is successful in the end.

[magnetman]

On 17/11/2007 at 06:52, magnetman said:

For slow engines (under 1,000rpm) it is possible to use a bicycle computer set to wheel circumference 1667mm and to km/h range, magnet on flywheel with sensor (reed switch) close to it. Every km/h on the display will be 10 rpm engine speed. Could put it on propshaft and double the result to get engine speed. Also gives running hours up to 12h for daily records.

Of course the BMC doesn't have an exposed flywheel. That was back in the day when I had a Russell Newbery. 

 

Probably best to do it on the gearbox output flange and multiply by reduction ratio. 

 

 

Edited January 23, 2022 by magnetman

[Phoenix_V]

50 minutes ago, magnetman said:

Of course the BMC doesn't have an exposed flywheel. That was back in the day when I had a Russell Newbery. 

 

Probably best to do it on the gearbox output flange and multiply by reduction ratio. 

 

 

wow you have been thinking about that for a long time

[Alan de Enfield]

47 minutes ago, Phoenix_V said:

wow you have been thinking about that for a long time

 

Fourteen years is quite a long time to be pondering a BMC flywheel.

 

Edited January 23, 2022 by Alan de Enfield