Kelvin

[koukouvagia]

Here's the genuine article:

 

It's 8" tall and 3" diameter, Alnwick!

Edited October 18, 2010 by koukouvagia

[rjasmith]

I agree that with an impulse mechanism it would be crucial to have a magneto running the right way.

However, when I tested my reconditioned magneto it was not attached to the engine or the impulse mechanism. As I said, one way it sparked, the other way it didn't.

I think there's a lot that I don't understand about magnetos. For example, why does one specialist website I've looked at warn against using modern carbon-cored spark plug leads and insisting that the old-fashioned wire cored lead is used?

Could this be the reason that my magneto burnt out? I had replaced the leads with modern leads just before it stopped working.

 

Yes - I think it could have been! The old enamel and other materials used as insulation in the HT windings were much more prone to overvoltage breakdown damage. Perhaps modern enamelled wire is better so a rewound mag may be able to withstand more abuse.

 

Using resistive leads is likely to allow the HT at the mag end to rise higher than if copper wire connects to the plug. Especially when you think how long the leads are on a Kelvin and therefore how high the resistance will be with the carbon leads (I think they're about 10K per foot!). I'd also avoid resistor cored spark plugs.

 

Was your old mag a 4 sparker like mine? On a K2 the 2 "spare" sparks on these are taken to a "spare" plug on the top of the crankcase just to ensure that the volts don't go too high on these leads either.

 

Richard

[NB Alnwick]

Here's the genuine article:

 

It's 8" tall and 3" diameter, Alnwick!

 

I wonder if we could get Richard (RLWP) to set up a production line?

[koukouvagia]

Thanks, Richard, that explains a lot. I probably made a very expensive mistake using modern HT leads.

 

 

Was your old mag a 4 sparker like mine? On a K2 the 2 "spare" sparks on these are taken to a "spare" plug on the top of the crankcase just to ensure that the volts don't go too high on these leads either.

 

Yes, my magneto is a 4 - sparker. I've not bothered to short out the spare sparks on the magneto I've adapted to battery and coil operation. Do you think I should?

 

BTW this thread's getting v. complicated. There are at least three different lots of technical questions: overheating, magnetos and carb fillers.

The sooner we get our own Kelvin section on this forum the better

Edited October 18, 2010 by koukouvagia

[rjasmith]

Here's the genuine article:

 

It's 8" tall and 3" diameter, Alnwick!

 

Wow! That's the one! Just the same as on Water-Lily! Does he have the Priming Gun as well?

 

I would echo Graham's request for data. Particularly what the volume of the lower chamber is, the diameter of the tubes and the all important bottom chamber refilling hole, ie it's precise size and position on the divider plate. Does the lid use a sealing washer of some sort?

 

There was too much going on during my involvement with Floating Kitchen to stop and look at Water-Lily's one properly.

 

So the ratio was 16:1 at some point then - I wonder if the company just revised it to 32:1 later rather like Seagull outboards went from 10:1(!) to 25:1 in the 60s.

 

Richard

[rjasmith]

Thanks, Richard, that explains a lot. I probably made a very expensive mistake using modern HT leads.

 

 

Yes, my magneto is a 4 - sparker. I've not bothered to short out the spare sparks on the magneto I've adapted to battery and coil operation. Do you think I should?

 

BTW this thread's getting v. complicated. There are at least three different lots of technical questions: overheating, magnetos and carb fillers.

The sooner we get our own Kelvin section on this forum the better

 

I definitely would - or at least take both of them to a spare spark plug - do you have the holder on your crankcase top just between the cylinders on the mag side? It keeps the sparks behind little holes so as to avoid blowing up any flammable vapours that might be lurking!!

 

Although with your mod, the ignition coil with its oil insulation is probably OK up to 100kV (I once did an electronic ignition mod on a Mini and found I could get 3" long sparks out of the coil HT nose - it didn't seem to mind but it couldn't have been good for it!!)

 

You are still "steering" the sparks through your mag though and you might start developing tracks across the rotor arm etc when it tries to fire the spare distributor points.

 

Richard

[RLWP]

I wonder if we could get Richard (RLWP) to set up a production line?

 

Your crystal ball is working well today Graham...

 

My heart says what a fantastic project

 

My head says I've got enough on my plate just now

 

I wonder how that will work out

 

Richard

[koukouvagia]

Your crystal ball is working well today Graham...

 

My heart says what a fantastic project

 

My head says I've got enough on my plate just now

 

I wonder how that will work out

 

Richard

 

If your heart wins, put me down for one

 

 

You are still "steering" the sparks through your mag though and you might start developing tracks across the rotor arm etc when it tries to fire the spare distributor points.

 

 

I remember now when I was testing my mod that I had sparks leaping all over the place inside the distributor cap. I covered the HT contact on the coil with a thick piece of rubber and all now seems to be OK.

BTW the more I hear about Kelvin extras, the more I'm intrigued. I'd never heard of the spark plug holder with the anti explosion screen before.

[MtB]

Ok, in the continued absence of a Kelvin board, I'll change the subject again!

 

Water pumps. Having though about the displacement format water pumps fitted to K series engines in a bit of detail now I think they are supremely unsuitable for connection to a 'closed system' like a skin tank.

 

The reason for this is that on each water pump stroke the system volume changes. No problem on a seawater or raw canal water cooling system. On the 'up' stroke about 70cc of water is drawn in from the canal (or sea) and on the 'down' stroke this water is expelled through the cooling system and out through the exhaust. When a keel cooling system or skin tank on the swim is connected however, things change. On the 'up' stroke the system volume reduces by 70cc, and on the 'down' stroke it increases by 70cc.

 

I can feel this effect just by holding one of the 30mm dia flexible hoses connecting my K1 to the skin tank. It noticeably bulges on the 'down' stroke of the water pump as water is forced up the connection pipe to the header tank, and shrinks on the 'up' stroke. Considerable stress must be occurring in the system.

 

This leads me to conclude that a closed system is not a great idea unless the header tank connection pipe is big enough to accommodate this volume change on each water pump stroke , OR a weir-type arrangement is used where the output of the water pump is discharged into the header tank as a flow indicator.

 

Hope I've explained this properly. If I haven't, I expect it's the Beaujolais. Chateau de la Terriere 2009. Highly recommended.

 

Mike

 

(Edited to correct spelling mistakes.)

Edited October 21, 2010 by Mike the Boilerman

[koukouvagia]

 

Water pumps. Having though about the displacement format water pumps fitted to K series engines in a bit of detail now I think they are supremely unsuitable for connection to a 'closed system' like a skin tank.

 

 

Since I've got raw water cooling I've never had to think about the problem you've identified with a Kelvin displacement pump in a closed system.

I know of one J2 owner who's fitted an impeller pump driven by a chain. It's a very neat installation and you can see a picture of it in this article reproduced on Mike Skyner's excellent Kelvin site.

[Proper Job]

Wouldn't it be fairly easy to overcome the varying volume by fitting a pneumatic type expansion tank in the closed loop?

 

Something similar to that fitted to central heating systems or indeed, domestic water systems on boats.

 

 

"....a weir-type arrangement is used where the output of the water pump is discharged into the header tank....." My JP discharges in to the header tank which is only a couple of feet above the highest point of the engine. It's then easy to check that all is well by doing a temperature check (hand on side of tank) and flow check by looking in to the top of the tank.

Edited October 22, 2010 by Proper Job

[BEngo]

Ok, in the continued absence of a Kelvin board, I'll change the subject again!

 

Water pumps. Having though about the displacement format water pumps fitted to K series engines in a bit of detail now I think they are supremely unsuitable for connection to a 'closed system' like a skin tank.

 

The reason for this is that on each water pump stroke the system volume changes. No problem on a seawater or raw canal water cooling system. On the 'up' stroke about 70cc of water is drawn in from the canal (or sea) and on the 'down' stroke this water is expelled through the cooling system and out through the exhaust. When a keel cooling system or skin tank on the swim is connected however, things change. On the 'up' stroke the system volume reduces by 70cc, and on the 'down' stroke it increases by 70cc.

 

I can feel this effect just by holding one of the 30mm dia flexible hoses connecting my K1 to the skin tank. It noticeably bulges on the 'down' stroke of the water pump as water is forced up the connection pipe to the header tank, and shrinks on the 'up' stroke. Considerable stress must be occurring in the system.

 

This leads me to conclude that a closed system is not a great idea unless the header tank connection pipe is big enough to accommodate this volume change on each water pump stroke , OR a weir-type arrangement is used where the output of the water pump is discharged into the header tank as a flow indicator.

 

Hope I've explained this properly. If I haven't, I expect it's the Beaujolais. Chateau de la Terriere 2009. Highly recommended.

 

Mike

 

(Edited to correct spelling mistakes.)

 

 

OK. The water pump has a big hollow bronze box on the outside. On the aft end of this, about 3/4 of the way up should be a tap. The purpose of this tap is to let some air into the big bronze box. The purpose of the air is to deal with changes in water volume and to stop the pump locking up if the seawater inlet is blocked. Just like a hydraulic accumulator it will absorb some of the pulsing which is inherent in a ram-pumped cooling system. The Instruction Manual describes how to get some air into the box- basically close the seacock (valve in the pipe from the cooling tank) and open the tap for 10 seconds or so. Then restore normal cooling.

 

In any event, if you have an open vented skin tank system any change in the amount of water in the engine itself should be compensated by a change of the water level in the header tank, even if the header tank is not part of a weir system. I would not worry about the stress in the system- it is insignificant compared with the stress caused by the combustion pressures. Do check that the pipes from the engine to the header tank are not obstructed- build debris, bits of rust from the inside of the engine, new header tank etc.-- I infer from your previous posts that the initial installer seemed to only work where there was a good hitching rail and somewhere to hang a 10-gallon hat.

 

Incidentally, the stroke of the water pump varies from model to model- the two cylinder engines have a shorter water pump crank throw than the the threes and the fours and sixes are each larger still. I presume that the K1 used a K2 waterpump crankshaft.

 

 

N

[rjasmith]

Excellent!

 

The last two posts got me thinking about pulsating pressure on the cooling system but when reading BEngo's post I realised my pump has a tap on the top rather than on the side halfway up.

 

So a quick delve into Mike Skyner's site to look at the parts drgs again and I remembered that there are two types of reciprocating pump. There is a single acting one which will vary the system volume on a closed system (ignoring the header tank for a moment) and a double acting one which presumably won't. The double acter presumably must push water out of the bit above the piston at the same time as it sucks into the bottom bit below the piston. This should mean that there is no net pressure change in the system on either an up or a down stroke?

 

Our K2 has a double acting pump and there is a tap but it's on the top of the box, not the side and I always thought it was there to bleed the pump and check for output.

 

Can anyone confirm if I'm right? (If not I'll have to brush up on the Glaswegian and give Andy a ring!)

 

Richard

[koukouvagia]

Excellent!

 

Our K2 has a double acting pump and there is a tap but it's on the top of the box, not the side and I always thought it was there to bleed the pump and check for output.

 

Can anyone confirm if I'm right? (If not I'll have to brush up on the Glaswegian and give Andy a ring!)

 

Richard

 

Yes, I've always thought it was a bleed cock. It is also useful for emptying water out of the pump when draining down the the system.

 

This is what the manual says:

"The cock on cover should be opened after starting up to release air from valve chambers. Cock should be closed immediately a solid jet of water appears on the discharge stroke."

[MtB]

Wouldn't it be fairly easy to overcome the varying volume by fitting a pneumatic type expansion tank in the closed loop?

 

Something similar to that fitted to central heating systems or indeed, domestic water systems on boats.

 

Yep I'd considered that, but CH and DHW expansion vessels are designed for slow changes in pressure, one or two cycles per hour or per day. Not five cycles a second for hours on end, day after day, for possibly weeks on end.... I just wouldn't trust one given the scope for consequential water pump failure and overheating breakdown should it give up the ghost.

 

I think the weir arrangement is the best answer. No components to wear out or fail there! Worries about accelerated corrosion due to aeration of the coolant are possibly exaggerated. I'm thinking that sea water is probably pretty well aerated and the engine is designed for sea water cooling. I think a weir type header tank acting as expansion vessel too is probably the right solution. I'll discuss it once again with Dick when I see him in early Nov. He's planning a visit to Reading see how my work is progressing so I NEED to get on with this, haha! ;-)

 

 

"....a weir-type arrangement is used where the output of the water pump is discharged into the header tank....."[/i] My JP discharges in to the header tank which is only a couple of feet above the highest point of the engine. It's then easy to check that all is well by doing a temperature check (hand on side of tank) and flow check by looking in to the top of the tank.

 

Your "JP"..??

 

Errr nope, sorry, you've got me there. A JP? Would that be some sort of long-obsolete old diesel engine or something?? ;-)))

 

Mike

[RLWP]

Right Mike, you've worried yourself silly over the pulsations, have you worked out what the pressure fluctuation actually is?

 

Richard

[MoominPapa]

Right Mike, you've worried yourself silly over the pulsations, have you worked out what the pressure fluctuation actually is?

Difficult to work that out, surely? You can find the change in volume OK, but the way the pressure changes depends on the elasticity of the hoses and the volume of any trapped gas, mainly.

 

MP.

[RLWP]

Difficult to work that out, surely? You can find the change in volume OK, but the way the pressure changes depends on the elasticity of the hoses and the volume of any trapped gas, mainly.

 

MP.

 

True. My guess it is four fifths of five eighths of F all, but it's clearly worrying Mike. You could always leave the lid of the expansion tank then you have no problem at all of course

 

Richard

[MtB]

Right Mike, you've worried yourself silly over the pulsations, have you worked out what the pressure fluctuation actually is?

 

Richard

 

No, but I think it's pretty high. If I hold the big fat sturdy 32mm diameter flexible hose connecting the outlet from the cylinder and head to the skin tank I can feel it bulge on each water pump stroke. Stretching the diamter of a hose like that takes some force given the wall is about 8mm thick and reinforced. Maybe I'll cut it and put a pressure gauge in to measure the peak pressure. Would be quite easy to do.

 

Given the reputation of Kelvin water pumps for fragility I see no point in stressing mine unnecessarily when it is easily avoided by better system design. In fact this could be the whole reason Kelvin water pumps are prone to failure.

 

Mike

[Proper Job]

....Given the reputation of Kelvin water pumps for fragility I see no point in stressing mine unnecessarily when it is easily avoided by better system design. In fact this could be the whole reason Kelvin water pumps are prone to failure.

 

Mike

What about playing some soothing music to it? It must get quite upset listening to that clunk, knock, bang, wheeze, clunk, knock, bang, wheeze noise all of the time

[MtB]

What about playing some soothing music to it? It must get quite upset listening to that clunk, knock, bang, wheeze, clunk, knock, bang, wheeze noise all of the time

 

Y'know I don't think you are taking this seriously at all Steve.

 

It's jealousy, I reckon! I expect Ocelot has one of them ordinary vintage diesels, Y'know, the grey ones. (Or heaven forbid, surely not one of those that only works if painted GREEN....?)

[NB Alnwick]

No, but I think it's pretty high. If I hold the big fat sturdy 32mm diameter flexible hose connecting the outlet from the cylinder and head to the skin tank I can feel it bulge on each water pump stroke. Stretching the diamter of a hose like that takes some force given the wall is about 8mm thick and reinforced. Maybe I'll cut it and put a pressure gauge in to measure the peak pressure. Would be quite easy to do.

 

Given the reputation of Kelvin water pumps for fragility I see no point in stressing mine unnecessarily when it is easily avoided by better system design. In fact this could be the whole reason Kelvin water pumps are prone to failure.

 

Mike

 

In our experience, the only parts of the Kelvin engine that are prone to failure are those parts that are not made by Kelvin - the water pump is not in that category. Ours has only ever needed the piston rod turning down (to eliminate a modest taper and some ovality) and re-packing in all of its 50 plus years! It still has its original leather piston seals!

[MtB]

In our experience, the only parts of the Kelvin engine that are prone to failure are those parts that are not made by Kelvin - the water pump is not in that category. Ours has only ever needed the piston rod turning down (to eliminate a modest taper and some ovality) and re-packing in all of its 50 plus years! It still has its original leather piston seals!

 

Graham,

 

The shattered non-return valve you mentioned the other day in your K3 water pump which lead to a major overheat and paint blistering off the heads doesn't count as a water pump failure then?!

 

;-)

 

Mike

 

 

Edit: Actually my apologies Graham. I'm confusing your K3 with Jim's K2. I've just noticed he mentions this incident the 'Old v. New' thread on the General Boating board.

Edited October 24, 2010 by Mike the Boilerman

[Proper Job]

Y'know I don't think you are taking this seriously at all Steve.

 

It's jealousy, I reckon! I expect Ocelot has one of them ordinary vintage diesels, Y'know, the grey ones. (Or heaven forbid, surely not one of those that only works if painted GREEN....?)

Is there any other colour?

 

I had a green engine in one of my previous boats as well:

Edited October 26, 2010 by Proper Job

[MtB]

Is there any other colour?

 

I had a green engine in one of my previous boats as well:

 

 

That's not proper green, that's 'eau de nil'. A right girly colour to paint yer engine I reckon.

 

Which brings me neatly to the next thing I'm wondering about... engine room colour schemes! As you can all see from the video my engine room is a fine mixture of old dirty pine, new dirty plywood and dirty grey or just plain rusty steel.

 

What colour scheme would be appropriate for an engine room containing a proper green K1??

 

Cheers,

Mike