Tiny Tach

I think you will find that the injector pipe is 6mm. Tiny Tack only offer two sizes, you want the smaller. When you fit it, you may like I had to, File the transducer face to give a tighter clamp round the injector pipe. Gives a more accurate reading.
 
In what way was it inaccurate? I mean how did you know?
I have fitted a Tiny Tach to my Volvo MD7. It seems to work fine, but I am very suspicious of the low rpm figures.

At around 3/4 throttle and a boat speed of about 6 knots it is only showing 1200 rpm, seems awful low to me. Tickover is 300rpm.
 
Just looked at the websites suggested by Sarabande. They raise more questions than answer them. You will have to enlighten me next time we meet.

And if you fitted one already in Pipedream, sounds like you just volunteered!

/forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

Oh, and, incidentally, are you 'breaking a leg' just now?
 
another way to record engine speed is using a bicycle computer with the magnet mounted on the gearbox output coupling and the reed switch close to it. set the computer to 'wheel circumference' of 1667mm and km/h units that will make 1km/h = 10rpm. just double and x10 the reading to get engine speed (assuming 2:1 box) most cycle computers only go up to 100km/h so it is limited to recording 2,000rpm and slower but its handy for tickover measurement etc.
 
[ QUOTE ]
In what way was it inaccurate? I mean how did you know?
I have fitted a Tiny Tach to my Volvo MD7. It seems to work fine, but I am very suspicious of the low rpm figures.

At around 3/4 throttle and a boat speed of about 6 knots it is only showing 1200 rpm, seems awful low to me. Tickover is 300rpm.

[/ QUOTE ]

I have one connected to my MD7a (Westerly Griffon) and tickover is around 870rpm, cruising around 2100rpm topping out at around 2550rpm. All of which is in line with the Volvo manual.
 
You can get bike computers for less than a tenner. I've just dug an old bike computer out of my old bike bits box and rigged it up on my Yanmar 2GM20 as I want to check revs against speed through the water. As a temporary rev counter it works fine.
 
The UK agent will send you the right one if you tell him what engine you have, but yes, it is 6mm for a 1gm10.
As well as displaying the rpm, it will also log engine hours and time to next service. As well as the 12v connection to the ignition switch it has an internal battery (which enables it to store the hours information), but this isn't replaceable. The first two I had lasted about 2 months before the display started to misbehave, firstly not storing the hours and then displaying spurious rev readings. I have yet to fit the 3rd replacement I've been sent, but if this one lasts as long as the others I'll just give up.
Just out of interest, I opened up one of the broken ones - the circuit including the soldered-on watch battery is encapsulated in a rubbery compound, so when they say the battery is not replaceable they really mean it. With care and determination you could replace it, or there is someone who actually offers this service - here.
In hindsight, I would seriously question why I ever wanted to know what revs my engine was doing, as my ears work fairly well.....
 
I used a Sigma BC906 cycle computer. £12 on eBay. Some cheaper ones don't have the option to set wheel circumference, using instead wheel diameter which reduces accuracy as it would have to be set to 21 inches which is a bit more than the 20.9 exact equivalent. the only problem is the wire from the display to the reed switch is a bit on the short side meaning the display needs to be fairly close to the engine. I don't know if a 'wireless' type would work through the deck boards I suppose it might. the wire on the 906 could possibly be extended to allow the display to be positioned in a more useful location.
 
[ QUOTE ]
The UK agent will send you the right one if you tell him what engine you have, but yes, it is 6mm for a 1gm10.
As well as displaying the rpm, it will also log engine hours and time to next service. As well as the 12v connection to the ignition switch it has an internal battery (which enables it to store the hours information), but this isn't replaceable.

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According to the website the current models use flash memory rather than having an internal battery. Is that not the case? I ask because I have been thinking I really, really need one. /forums/images/graemlins/grin.gif
 
I only want to check the revs as part of/after a service, so for me a point and shoot rev counter that counts reflections off a sticker on the flywheel is fine and needs no installation either.
Why do you want a rev counter and all the installation issues that it brings?
 
[ QUOTE ]

According to the website the current models use flash memory rather than having an internal battery. Is that not the case? I ask because I have been thinking I really, really need one. /forums/images/graemlins/grin.gif

[/ QUOTE ]
It looks as though you're right- "Flash memory replaces internal battery"- in which case they have changed it since last summer - perhaps they changed the design because they got sick of me returning the broken ones!
 
Thanks for that info, it sounds as if mine is somehow only counting about half the revs /forums/images/graemlins/confused.gif

I will check it further and see if I can work out what is going on. The hours counter is useful though.
 
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