Rev counter

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ratty said:
Any one will do. They do 52mm ones in most places. These will fit straight into the defender dash holes. It takes it's drive from a connector on the back of the alternator.
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not to doubt you but i was told that only certain rev counters will work with diesal engines on the landys?..some when you connect them tickover really high according to the guage,unless i was drunk and wasnt listening properly..i have a rev counter in my dash pod and it has 4 settings on the back none i can get to work properly,so any info would help me aswell
 
wiltshire landyman said:
not to doubt you but i was told that only certain rev counters will work with diesal engines on the landys?..some when you connect them tickover really high according to the guage,unless i was drunk and wasnt listening properly..i have a rev counter in my dash pod and it has 4 settings on the back none i can get to work properly,so any info would help me aswell
Click to expand...

diesel rev counters tend to max out at around 5000rpm. Petrol ones go up to around 9000rpm.

I wasn't aware of issues regarding the reading when a petrol one is used with a diesel or vice versa as most, like you say, have adjusters on them to compensate.:confused:
 
I may be able to shed a little more light on the problem, as far as i can remember (from when I used to rally my mini) the reve counter did have 3 settings on it, 3 cylinder,4 cylinder & 8 cylinder, the trigger wire was connected to the ignition coil feed, basicaly the rev counter counted the number of pulses from the points (now day this would be the ecu) Deisels obviously don't have this type of electical circuit.
Now, on my outboard 2 cylinder engine the rev counter has a setting marked "alt", this is the output that I think that RATTY is talking about, So in that case, the rev counter will need to accept an altenator input, (i mignt try the one from my boat first), Then there may be another hurdle, does the altenator revolve at the same speed as the crankshaft? I dont think it does (this will be related to the size of the pulleys?) I think!
So, it looks like you need a revcounter that recieves an altenater output, But it's only worth doing if an accurate speed can be recorded.
Hope that makes sense!
 
Gordo 90 said:
I may be able to shed a little more light on the problem, as far as i can remember (from when I used to rally my mini) the reve counter did have 3 settings on it, 3 cylinder,4 cylinder & 8 cylinder, the trigger wire was connected to the ignition coil feed, basicaly the rev counter counted the number of pulses from the points (now day this would be the ecu) Deisels obviously don't have this type of electical circuit.
Now, on my outboard 2 cylinder engine the rev counter has a setting marked "alt", this is the output that I think that RATTY is talking about, So in that case, the rev counter will need to accept an altenator input, (i mignt try the one from my boat first), Then there may be another hurdle, does the altenator revolve at the same speed as the crankshaft? I dont think it does (this will be related to the size of the pulleys?) I think!
So, it looks like you need a revcounter that recieves an altenater output, But it's only worth doing if an accurate speed can be recorded.
Hope that makes sense!
Click to expand...
so i wasnt as drunk as i fort then:D
 
Continuing from what Gordo says, the alt ones need to be matched up to an extent because for example: there are 2 pully sizes for 300tdi alt's - some have adjusters on them that will let you tweak them.
 
I think your right, to prove the altenater speed issue, if you marked the altenater pulley at the top and marked the crankshaft pulley at the top, turn the engine over a couple of times until the mark on the crankshaft is back at the top and check the altenater mark, they both must be at the top, If not they are spinning at different speeds so fittinga rev counter is a waste of time really (if I've got it right, Bearing in mind I dont get My Landy till next Saturday so I dont know the pulley and belt set up).
 
They are without a doubt spinning at different speeds, the crank pully is huge in comparison to the alt. The tachos take this into consideration though, for example if the alt does 2.5 revs per 1 of the crank it will know that and the adjustment is set up like that.
 
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In that case it may be worth me trying to find a suitable rev counter for my new truck.
Thanks.
 
A fair point, I suppose I am concerned about over reving the lump and I find on my Navara I can get better fuel ecconomy by keeping the rev in certain rev range!
 
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