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1935Hillman
Joined: 06 Apr 2010 Posts: 257 Location: Hampshire
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Posted: Fri Jul 01, 2016 12:34 pm Post subject: Rev counter link up |
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I am still trying to get my little brain round my rev counter link up. I have fitted a Lucas dynamo with rev counter take off at the blunt end and need to connect it to my rev counter.
The crank and dynamo pulleys are both the same 4" diameter which means that the ratio between these pulleys is 1:1 and the take of at the back of the dynamo is turning at the same rate as the crank i.e. engine revs.
The rev counter is a 3" Smiths type marked 2-1 which I assume is the gearing in the gauge itself.
My question is this: Do I simply need to hook up the dynamo with the rev counter and the gauge will read correctly or do I need a gear off the back of the dynamo to gear it 1:2 which will then be converted back at the gauge which is rated 2:1 ?
Help please
Many thanks,
Tim |
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peter scott
Joined: 18 Dec 2007 Posts: 7121 Location: Edinburgh
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1935Hillman
Joined: 06 Apr 2010 Posts: 257 Location: Hampshire
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Posted: Fri Jul 01, 2016 10:39 pm Post subject: |
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Hi Peter,
Thanks for your reply. I had already asked them but their specialist is away for a few weeks and I was just doing some homework in the meantime !
Terribly impatient !!
Any opinions that might help me understand in the meantime would be very welcome still |
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MVPeters
Joined: 28 Aug 2008 Posts: 822 Location: Northern MA, USA
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Posted: Sun Jul 03, 2016 12:24 am Post subject: |
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Can you hook up the bits & bobs you do have & see what the rev-counter says?
If you assume the idle speed is, what, 7 or 800 rpm? see if the rev-counter is similar. (A dwell meter could be used to see the actual idle speed if you have or could borrow one).
If it's half, or double, that, it will tell you what you need to add or remove. I don't think you can damage anything by trying this. _________________ Mike - MVPeters at comcast.net
2002 MINI Cooper 'S' |
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jp928
Joined: 07 Jun 2016 Posts: 249 Location: Australia
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Posted: Sun Jul 03, 2016 9:09 am Post subject: |
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Absent anything else that can count revs, if you make one big white mark on your fan belt and hold a fluro lamp over it, the white mark will be stationery at 3000rpm; with 2 equally spaced (preferable but not mandatory) white marks, at 1500rpm - should be able to do this with an idle adjustment? This assumes your AC power is 50cycle, which I think is true for UK. For USA the rpm would be 3600 and 1800.
You can probably get an app for a smart phone that can do optical rev counting.
jp |
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1935Hillman
Joined: 06 Apr 2010 Posts: 257 Location: Hampshire
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Posted: Sun Jul 03, 2016 12:55 pm Post subject: |
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Both very good suggestions. I must admit I was thinking of 'just trying it to see what revs the gauge showed at idle and then gently increasing the revs. |
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47Jag
Joined: 26 Jun 2008 Posts: 1480 Location: Bothwell, Scotland
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Posted: Sun Jul 03, 2016 1:25 pm Post subject: |
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Tim,
The fact that the Rev counter has 2:1 on it suggests to me that it should be camshaft driven.
Art |
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