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Measuring idle rpm


Cloudinspector

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True,

 

But on a nice vintage twin the two adjacent firing stokes can usually be clearly heard separately at tickover speed, which is what we've turned to discussing!

 

You might remember me telling you your Gleniffer was idling at just over 200 rpm at Alvecote gathering last year. The two adjacent beats although individually distinguishable were easy to count as one even at that speed. Over the 10 second period I used (checked twice) I counted 17 beats, x 12 = 204 rpm.

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You might remember me telling you your Gleniffer was idling at just over 200 rpm at Alvecote gathering last year. The two adjacent beats although individually distinguishable were easy to count as one even at that speed. Over the 10 second period I used (checked twice) I counted 17 beats, x 12 = 204 rpm.

 

 

That's interesting. To my ear the two beats are totally and completely separated at tickover on the Gleniffer. So separate that I even notice a difference in tone and nature between the two separate puffs from the exhaust.

 

I'd agree with Tim though, that once the engine speed gets up to about 400rpm they completely meld together into one single bang to my ear. I'd put the limit at about 350rpm actually.

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Well maybe the fact I'm going deaf helps rolleyes.gif

 

ETA: Just remembered I did a similar check on video of recently rebuilt 6L3, which was found to be idling around 200 rpm as well. Even with six cylinders the repeat pattern of exhaust note was just about distiguishable to count as one - helped by a bit of tape on the injection pump driveshaft as well.

 

Yes I need to get out more wink.png

Edited by by'eck
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If you like old school solutions, as I do, try one of these - click image

 

$_57.JPG

 

Bought similar one on eBay some time ago for very little. It samples revs over a fixed few seconds whilst dial moves around scale, after which it freezes to display actually revs. Used on the end of injection pump camshaft then doubled reading.

 

Gardner%20TICK%20OVER%20002.jpg

 

Thanks, by'eck I got this excellent 'bit of kit' and found the shaft in the picture above is turning at 760rpm.

 

It would appear from plans that this is chain driven from the crankshaft and is a smaller pulley/chainwheel than that on the crankshaft, so what would be the engines rpm?.

 

Sounds a bit like a GCE maths exam question circa 1965, but if any one has the diametre of the 2 wheels it would be helpful.

 

It's a 2LW engine, I suspect tickover is about 320rpm.

 

Thanks, as you said by'eck - the definitive bit of kit, a bit of a collector's item and accurate, tested it on my battery drill rev output, came out with the revs indicated by the manufacturers.

 

Regret cannot use it directly onto crankshaft as there is insufficient room.

 

L.

Edited by LEO
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Yes nice kit. I think the primary application was to measure cutting speeds for lathes - that's where the wheel attachment marked yards came in. There is mention of this in instruction sheet I got with mine.

 

Sorry not that familiar with Gardner engines so can't help with shaft speed - sounds like it might be crankshaft x 2 though. Try my listening for single beat test over 10 seconds x 12 to confirm.

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Gardner%20TICK%20OVER%20002.jpg

 

Thanks, by'eck I got this excellent 'bit of kit' and found the shaft in the picture above is turning at 760rpm.

 

It would appear from plans that this is chain driven from the crankshaft and is a smaller pulley/chainwheel than that on the crankshaft, so what would be the engines rpm?.

 

Sounds a bit like a GCE maths exam question circa 1965, but if any one has the diametre of the 2 wheels it would be helpful.

 

It's a 2LW engine, I suspect tickover is about 320rpm.

L.

 

That's the dynamo drive, and several different ratios were fitted. You would have to establish what yours is before getting any meaningful info from it.

 

Tim

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Interesting that you raise this question, as I was wondering about the same thing. I think that my 2LW is ticking over a bit too quickly. What is your target idling rpm? I have heard that 420 is about right.

 

That's correct. According to my manual it should be set at 420 once the engine has warmed up.

I think mine's idling a bit fast also. There's a main idle set screw which should be set around 410 rpm then a fine adjustment screw to set at 420.

Actually the Gardner Stated idle rpm of 420rpm is meant for automotive build engines, the stated for the marine variants (if you have the marine specific notes) is 330rpm. All the LW's for narrowboats we do come out of the workshop set at this. the only thing you need to watch out for on a 2 or 3LW is what flywheel you have fitted as if it has one of the lighter weight automotive flywheel variants then it might not like the 330rpm.

Edited by martyn 1
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That's the dynamo drive, and several different ratios were fitted. You would have to establish what yours is before getting any meaningful info from it.

 

Tim

 

 

This can be established by turning the engine over by hand. Count how many flywheel revolutions (and part revolutions, if any) it takes to turn the dynamo drive through exactly one revolution.

 

Then use the ratio to multiply up the reading from the tacho.

(Assuming there is a way of turning over your engine by hand!)

(Do 2LWs come with a hand start option or are they all electric start?)

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Actually the Gardner Stated idle rpm of 420rpm is meant for automotive build engines, the stated for the marine variants (if you have the marine specific notes) is 330rpm. All the LW's for narrowboars we do come out of the workshop set at this. the only thing you need to watch out for on a 2 or 3LW is what flywheel you have fitted as if it has one of the lighter weight automotive flywheel variants then it might not like the 330rpm.

 

Another thing I've learned. My marine 4LW is set up for 420 rpm Because my manual says 330 rpm only for 5 & 6LWs.

So you think I'll be OK altering things down to 330rpm? It'll sound even better

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Another thing I've learned. My marine 4LW is set up for 420 rpm Because my manual says 330 rpm only for 5 & 6LWs.

So you think I'll be OK altering things down to 330rpm? It'll sound even better

 

I have my 4LW set to about 380 rpm, it seems happy at that (heavy generator flywheel).

 

Tim

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Thanks for all the input, lots to ponder - now if I drill a hole in the bathroom wall, I could get a reading direct off the crankshaft......

 

I wondered what the drive was for, have seen them running on bigger engines - I have a DVD filmed at Amersham Fair, will try to post.

 

How does one tell which type of flywheel is fitted - is one thicker than the other?.

 

Thanks once again.

 

L

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How does one tell which type of flywheel is fitted - is one thicker than the other?.

 

We are not talking one or the other, we are talking many hundreds of slight variants. Its fairly rare we see two Gardners with the same flywheels if they originally were from rail traction,generator or automotive. If the engine was a genuine marine fitted with a 2uc then the flywheels would be the same from one to the next.

 

Essentially you don't want to be trying to drop the rpm down if your flywheel is an automotive one which is only a little thicker than the ring gear. the flywheel variants vary from easily carried by one person to a bloody heavy lift for two.

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I wondered what the drive was for, have seen them running on bigger engines - I have a DVD filmed at Amersham Fair, will try to post.

 

L

 

Here is mine:-

 

 

AC7mod-3.jpg

 

 

Tim

 

Edited by Timleech
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We are not talking one or the other, we are talking many hundreds of slight variants. Its fairly rare we see two Gardners with the same flywheels if they originally were from rail traction,generator or automotive. If the engine was a genuine marine fitted with a 2uc then the flywheels would be the same from one to the next.

 

Essentially you don't want to be trying to drop the rpm down if your flywheel is an automotive one which is only a little thicker than the ring gear. the flywheel variants vary from easily carried by one person to a bloody heavy lift for two.

 

Thanks, not really interested in getting the revs too low as have heard that if the engine spins too slowly it can cause hydraulic pressure problems with the gearbox (PRM 260) as well as problems with the engine.

 

Tim - The photo will not open for some reason.

 

The Hasler instrument is excellent might be about 90/100 years old, no instructions with it.... nice have something Swiss made and containing no plastic...

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Thanks, not really interested in getting the revs too low as have heard that if the engine spins too slowly it can cause hydraulic pressure problems with the gearbox (PRM 260) as well as problems with the engine.

 

As I said 330rpm wont hurt it as its stated by Gardner as a standard (flywheel dependent), I wouldnt suggest going below the 330 as the oil pressure does start to drop off, you are right about the gearbox issues but it is interesting that in PRM's own documentation they don't guarantee positive engagement below 1500rpm which is amusing seem as most of the old engines that they are fitted to in narrowboats wont do that flat out.

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Try it now...

 

 

Tim

 

Thanks, good picture, I can now see why you have to 'hit the button' to get it to fire up quickly.

 

Hopefully my 'film' will follow soon.

 

L.

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Try it now...

 

 

Tim

 

Hi,

 

Film herewith, 2 Gardners at Amersham Fair generating power for the 'Bumper cars' (about 2009).

 

For the observant the clip should really be called 'The Lady Vanishes'.

 

 

 

 

L.

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  • 2 weeks later...

Finally got round to having a tinker. I bought myself one of the suggested digital tachometers off eBay and set the idle at 370 rpm using the method described in the manual.

However I can't get the idle rpm below 360 regardless of how far I unscrew the hexagon headed slow running adjustment screw (1st pic). I've then done the final setting at 370 using the flanged sleeve-nut at the rear of the governor casing ( 2nd pic).

Any ideas folks?

 

9B827C2A-9235-4AF1-AD9C-8EBE5E60A7A6_zps

 

288C7F95-C0F4-4F06-8E25-005387826BA0_zps

Edited by Cloudinspector
  • Greenie 1
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You will most likely need to run through the entire governor setting procedure as i expect somewhere along the line it is incorrectly set. The full procedure is in the manual if you have one of the later versions of it.

 

1. In short disconnect the link rod between governor and pump

2. remove the front cover from the front of the injector pump and set the rack a 1/32" from the full stop position.

3. remove bung in side of governor housing and manually hold the weights fully open.

4. now adjust the length of the link rod until it can be refitted with 2 and 3 above still in those positions.

5. refit bung and front cover.

6. reset injector pump buffer if required

7. reset idle, high speed, stop lever, cam angle as/if required.

 

Martyn

 

P.s like your profile pic Cloudinspector, Looks distinctly like this one on our site. Of course you asked to use it, didn't you wink.png

Edited by martyn 1
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You will most likely need to run through the entire governor setting procedure as i expect somewhere along the line it is incorrectly set. The full procedure is in the manual if you have one of the later versions of it.

 

1. In short disconnect the link rod between governor and pump

2. remove the front cover from the front of the injector pump and set the rack a 1/32" from the full stop position.

3. remove bung in side of governor housing and manually hold the weights fully open.

4. now adjust the length of the link rod until it can be refitted with 2 and 3 above still in those positions.

5. refit bung and front cover.

6. reset injector pump buffer if required

6. reset idle, high speed, stop lever, cam angle as/if required.

 

Martyn

 

P.s like your profile pic Cloudinspector, Looks distinctly like this one on our site. Of course you asked to use it, didn't you wink.png

 

 

7. Check Bank Account and if sufficient funds, call in the experts when the whole things goes clunk or get a rag ready (to cover air filter) when you get a 'runaway'.

 

L.

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Ye of little faith. If the instructions in the manual are followed to the letter then all will be fine. Or you could follow what should be 0. in the list above in some instances when I have had to deal with the aftermath of people fiddling.

 

0. If you don't fully understand what is in the points below. KEEP YER FINGERS OUT OF IT!!!!!!! biggrin.png

 

 

OH and just to clarify for anyone reading the above list. 1. to 6. along with everything in 7. except for idle and high speed adjustment should be done with the engine STOPPED!!!!!!!!

Edited by martyn 1
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You will most likely need to run through the entire governor setting procedure as i expect somewhere along the line it is incorrectly set. The full procedure is in the manual if you have one of the later versions of it.

 

1. In short disconnect the link rod between governor and pump

2. remove the front cover from the front of the injector pump and set the rack a 1/32" from the full stop position.

3. remove bung in side of governor housing and manually hold the weights fully open.

4. now adjust the length of the link rod until it can be refitted with 2 and 3 above still in those positions.

5. refit bung and front cover.

6. reset injector pump buffer if required

7. reset idle, high speed, stop lever, cam angle as/if required.

 

Martyn

 

P.s like your profile pic Cloudinspector, Looks distinctly like this one on our site. Of course you asked to use it, didn't you wink.png

Right, I've found the correct procedure in the manual and along with your simple explanation it all makes sense. However can you clarify what you mean by the injection pump front cover. Is it the cover through which the return spring enters the pump?

BTW I can honestly say I've no idea where I stole that photo from. If it was from you then I apologise for not asking first.

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I find that tinkering helps you understand how thinks work and it's so satisfying when you solve a problem by learning how to do it yourself. The secret is knowing your limits.

I own a 1956 VW and I've learnt so much by tackling stuff myself with the help of others.

Edited by Cloudinspector
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