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Engine hour / rev counter


mike-h

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Is there a simple way to fit an hour counter to a BMC 1.8?

 

I'd also like to fit a rev counter, I believe the 2 can be combined. Can anyone provide an easy way to do this.

 

Many thanks.

 

Don't know about the rev counter, which would need some kind of sensor, but we have an engine hours counter, or rather we have an ignition-on hours counter which is just wired to the back of the ignition switch. Unless you do something odd with your engine "ignition on" equals "engine running" give or take a few seconds.

 

We have a BMC 1.8 as well btw

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As separate items Hour meter is dead simple - just connect to ignition switch such that when ignition

is on - counter runs. A bit crude but effective. Rev counter is a bit trickier as it requires a connection

to the alternator - and not all alternators have the appropriate terminal - IIRC it is a direct connection

to ONE of the field windings (if I'm wrong on this someone will be along in a mo to correct it) - this allows

the tacho to measure the rpm of the alternator - you then have to calibrate the unit to allow for the

ratio between the engine rpm and the alternator rpm. If you get a combined unit then you may

have a choice of "engine hours" - either hours running regardless of speed - as per the separate

hour meter, or hours at (say) 2000 rpm - this may give a more accurate indication of the

work done by the engine, but I'm not really convinced of the value of the difference.

 

springy

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Is there a simple way to fit an hour counter to a BMC 1.8?

 

I'd also like to fit a rev counter, I believe the 2 can be combined. Can anyone provide an easy way to do this.

 

Yes its 4 wires two of which are the power

Using a diesel Tiny Tach

A4-flyer.gif

Very good product simple to fit.

Gives you service intervals as well

Parent company in the US is here

http://www.tinytach.com/tinytach/diesel.php#

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You can buy an electronic rev counter that has engine hours built in.

 

But as Springy says, you need a terminal on your alternator suitable to drive it, which not all original alternators on a BMC 1800 are likely to have.

 

If you have a "W" terminal, (unlikely to be used for anything currently, if you don't have these meters), then you are set. But you may find you have connectors that it's not obvious what they are...)

 

If not, it is apparently possible to modify, (or have modiefied) an existing alternator.

 

If you post a picture of your alternator, and it's terminals, one of the gurus, (not me!), will be able to put you straight.

 

ASAP Supplies do suitable combined rev counters / hour meters. We found the best chice was the one with max displayed revs of 3000RPM, as it will not be pushed to anything like that in normal use. With the more typical 4000 RPM meters you are really only using about a third of the dial in normal use.

 

It will need calibrating, but there is a trick to doing this with a bike computer costing under a tenner, if you don't have any other independent way of measuring engine RPM.

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You can buy an electronic rev counter that has engine hours built in.

 

But as Springy says, you need a terminal on your alternator suitable to drive it, which not all original alternators on a BMC 1800 are likely to have.

 

If you have a "W" terminal, (unlikely to be used for anything currently, if you don't have these meters), then you are set. But you may find you have connectors that it's not obvious what they are...)

 

If not, it is apparently possible to modify, (or have modiefied) an existing alternator.

 

If you post a picture of your alternator, and it's terminals, one of the gurus, (not me!), will be able to put you straight.

 

ASAP Supplies do suitable combined rev counters / hour meters. We found the best chice was the one with max displayed revs of 3000RPM, as it will not be pushed to anything like that in normal use. With the more typical 4000 RPM meters you are really only using about a third of the dial in normal use.

 

It will need calibrating, but there is a trick to doing this with a bike computer costing under a tenner, if you don't have any other independent way of measuring engine RPM.

 

 

 

Thanks for your replies. Cant see how the Diesel Tiny Tach works. I'll probably go with the hour counter only.

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It has a sensor which is mounted on one of the injector pipes - presumably

doesnt matter which one, as long as you can get at them (some listers

would be difficult).

 

springy

 

 

I hope their "noise discrimination" has improved. Very may years ago whilst on a course given by one of the leading makers of engine tuning equipment, which at that time was only available for spark ignition engines, we were told of the new developments for diesels and it got the rpm info from the injector pipe pulses. It reportedly worked very well in the lab but as soon as it was tried for real the RPM went all over the place. Turned out to also be measuring the timing chain slap and other mechanical noise as well. :lol:

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It will need calibrating, but there is a trick to doing this with a bike computer costing under a tenner, if you don't have any other independent way of measuring engine RPM.

 

Not as easy as it appears if your engine doesnt reach full revs as mine didnt. I spent 2 days trying to do mine gave up and got the tiny tach

 

I hope their "noise discrimination" has improved. Very may years ago whilst on a course given by one of the leading makers of engine tuning equipment, which at that time was only available for spark ignition engines, we were told of the new developments for diesels and it got the rpm info from the injector pipe pulses. It reportedly worked very well in the lab but as soon as it was tried for real the RPM went all over the place. Turned out to also be measuring the timing chain slap and other mechanical noise as well. :lol:

 

Much improved works like a dream and as easy to fit as an hour counter.

Just a sensor on the injector pipe and power.

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I hope their "noise discrimination" has improved. Very may years ago whilst on a course given by one of the leading makers of engine tuning equipment, which at that time was only available for spark ignition engines, we were told of the new developments for diesels and it got the rpm info from the injector pipe pulses. It reportedly worked very well in the lab but as soon as it was tried for real the RPM went all over the place. Turned out to also be measuring the timing chain slap and other mechanical noise as well. :lol:

 

I had a similar adaptor for early diesel use to convert the petrol engine tuner in my garage business. It worked OK but was quite critical on just the correct tightening of the clamp-on injector pipe sensor. I notice that this one just says to tighten up fully (or words to that effect). If it does what it says on the box then it is a very simple method of achieving the OP's request providing you have a suitable injector pipe with a straight run somewhere convenient for mounting the pipe sensor. One thing we couldn't do with customers' cars was to scrape the paint off the injector pipe, as these instructions require, so it may be that clamping onto a clean pipe would improve the signal transmission.

Roger

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A friend has a Ruston-Hornsby and he has a clamp-on hour counter which somehow or other works on vibration when the engine is running. No electrical connections. He reckons it is quite accurate too.

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Not as noiseeasy as it appears if your engine doesnt reach full revs as mine didnt. I spent 2 days trying to do mine gave up and got the tiny tach

 

 

 

Much improved works like a dream and as easy to fit as an hour counter.

Just a sensor on the injector pipe and power.

Thanks for this info. Seems like the easiest solution i've seen. What engines did you fit this to? If it works on pulses but can be corrupted by other noise I'd be concerned as the BMC 1.8 is not the quietest

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Thanks for this info. Seems like the easiest solution i've seen. What engines did you fit this to? If it works on pulses but can be corrupted by other noise I'd be concerned as the BMC 1.8 is not the quietest

Not sure about UK pricing of that thing, but it didn't look particularly cheap in dollars.

 

If your alternator already had the required "W" terminal, I can't see it is any more disturbance to fit a full blown alternator sensed tacho than the "Tiny Tach", to be honest.

 

We had no issues doing this, although you do need somewhere you can mount the instrument in a standard 85mm hole. If space at the control panel end were at a premium, I can see the Tiny Tach might be easier to find space for.

 

We had no issues calibrating with a cheap cycle computer, (on a BMC 1800).

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Is there a simple way to fit an hour counter to a BMC 1.8?

 

I'd also like to fit a rev counter, I believe the 2 can be combined. Can anyone provide an easy way to do this.

 

Many thanks.

 

 

Hi

 

12V hour counters are available from many suppliers, just connect the live to the ignition on wire.

 

RS Components

 

Alex

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Hi

 

12V hour counters are available from many suppliers, just connect the live to the ignition on wire.

 

RS Components

 

Alex

Thanks to all for your advice. Special private note to Sir Nibble. (#15) I was relieved to learn from my son that KISS might not be a term of affection in this instance but merely advice to keep life simple!

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KISS.

Buy a rev counter and connect it to the alternator. Alternators without rev counter terminals are now so old as to be not really worth keeping for the most part, and adding the output to an alternator without is dead easy.

 

A customer of mine is looking for a tacho to suit a big Kelvin, which has a nominal speed range of about 180 to 1000 rpm. They're fed up with replacing expensive very long drive cables on the mechanical tacho :lol:

I could probably rig something up from the alternator (AC30 AFAIR) but most of the electronic analogue tachos are designed for much higher rpm.

I've emailed the tinytach people to ask about minimum rpm, first they came back with 300 rpm but then had another think and said it ought to do 150.

I don't suppose anyone here has any real world experience of this aspect? Or a low speed electric tacho lying around in their shed? the later versions of the engine had a little tacho generator on the fuel pump drive, but they're obsolete now (and probably very expensive new).

 

Tim

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I'll be damned if I can now find the reference (for the diesel Tiny Tach), but thought I saw it only updated it's display every two seconds.

 

Sounds OK-ish if you just wanted to see what it's doing, but if you were actually in process of changing speed, I wonder how quickly it would accurately reflect what you are doing, particularly if the pulses it's measuring are infrequent, because the engine is a slow running one.

 

Obviously it works for Julian, but I do wonder if I strapped a sensor to my rattling BMC whether the only thing it would detect is the genuine passage of fuel down an injector pipe.

 

A cycle computer would work perfectly on the Kelvin, BTW, and cost less than a tenner.

 

OK it doesn't have the "looks" to go with a Kelvin, but does the Tiny Tach look that much different from a cycle computer ?

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I'll be damned if I can now find the reference (for the diesel Tiny Tach), but thought I saw it only updated it's display every two seconds.

 

Sounds OK-ish if you just wanted to see what it's doing, but if you were actually in process of changing speed, I wonder how quickly it would accurately reflect what you are doing, particularly if the pulses it's measuring are infrequent, because the engine is a slow running one.

 

Obviously it works for Julian, but I do wonder if I strapped a sensor to my rattling BMC whether the only thing it would detect is the genuine passage of fuel down an injector pipe.

A cycle computer would work perfectly on the Kelvin, BTW, and cost less than a tenner.

 

OK it doesn't have the "looks" to go with a Kelvin, but does the Tiny Tach look that much different from a cycle computer ?

 

The display is 20 feet or so from the engine, not sure how to do that with a cycle computer, ISTR the one I had was 'cordless'. Also the tiny tach may be 'tiny', but I'll guess that a cycle computer display might be 'tinier' and hard to read at a distance. I don't see the tinytach as the perfect answer, but it looks like one possibility.

The rapid updating bit might not be hugely important in this particular case, the main need for the tacho is when driving auxiliary machinery from the main engine and is not changed rapidly.

 

BTW I've got a couple of brand new old stock mechanical tachos here with hour meters, scale up to 2500 rpm, with drive cables maybe 2 or 3m long, open to offers.

 

 

Tim

Edited by Timleech
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KISS.

Buy a rev counter and connect it to the alternator. Alternators without rev counter terminals are now so old as to be not really worth keeping for the most part, and adding the output to an alternator without is dead easy.

 

Got some sort of 127 alternator upgrade but don't possess the know-how!

 

A quick sketch or instructions would be greatly appreciated.

 

Looked at the Standard Tiny Tach - £55.00 - 5 year battery life - battery non replaceable. Can't be bothered with all that.

 

Thanks

 

GB

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Got some sort of 127 alternator upgrade but don't possess the know-how!

 

A quick sketch or instructions would be greatly appreciated.

 

Looked at the Standard Tiny Tach - £55.00 - 5 year battery life - battery non replaceable. Can't be bothered with all that.

 

Thanks

 

GB

 

 

Hi

 

Is this any help alternator

 

Alex

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The display is 20 feet or so from the engine, not sure how to do that with a cycle computer, ISTR the one I had was 'cordless'.

I've no experience of cordless cyclo computers, but would be disappointed if they transmitted much further than from bike forks to handlebars - otherwise you would keep getting other people's readings, when used for what they are intended!

 

I'd only try and use "wired" in a boat application, and there is usually just a twinned wired to the sensor, so just a case of cutting and extending that, i would have thought.

 

I can't see why you should not have a bike computer by the hatch of a back cabin monitoring an engine in a proper engine room.

 

Agree it's not the most appealing of arrangements though.

 

I certainly struggled to find a "proper" alternator driven tacho (80mm hole type) that had a range lower than 3,000 RPM max, at a reasonable cost. Acceptable with a BMC, (using about half the scale much of the time), but perhaps not mega-useful on a Kelvin.

 

In some way there, I guess, digital readout is preferable.

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I can't see why you should not have a bike computer by the hatch of a back cabin monitoring an engine in a proper engine room.

 

My application isn't a narrow boat, it's a 300 bhp engine, with wheelhouse instruments :lol:

 

Tim

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My application isn't a narrow boat, it's a 300 bhp engine, with wheelhouse instruments :lol:

 

Tim

Fair enough!

 

So far as I know a wired bike sensor is nothing more than an encased microswitch on the end of a bit of wire. I suspect if you made the bit of wire 100 feet long, it would still work.

 

(Sorry, I realise I'm using outdated Imperial units, for those not old enough to know what a foot is....)

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