Kelvin starting problem

[MtB]

The K1 used to start beautifully initially and very easily by hand. This has all changed now. It has been getting progressively more difficult to start until to the point came when when hand-starting was no longer possible because it just won't fire on petrol reliably and consistently. I always have to use the electric start.

 

The problem has been a progressive deterioration, not a sudden change. A short while after I first acquired the engine I found I could no longer start it 100% reliably on my first attempt. Failure to fire on the second firing stroke was beginning to occur. It would usually start normally on my second or third attempt, but then it grew worse. It became quite difficult to hand start due to erratic and unpredictable/random firing so I resorted to using the starter motor. At first I put it down to the extremely cold weather but in March there was no improvement, so I began to suspect the old petrol I was using. I resolved to chuck away the remainder of my six-month-old petrol and get some new.

 

On Saturday I tried starting it with new petrol, fully expecting a major improvement in starting behaviour, but still no change. It has become worse in fact, so I definitely have a problem.

 

The engine fires on the first firing stroke perfectly but then misses on subsequent firing strokes and stops. Using the electric start eventually gets it running, firing occasionally and very randomly at first. After multiple re-starts it begins to run more steadily on alternative firing strokes i.e. firing once every four revolutions, running very slowly. Then after a minute or so of this it eventually improves and begins to fire regularly on every firing stroke so the engine speed rises to about 450 rpm, the petrol runs out and I can change over to diesel as normal.

 

 

Action taken so far, with no improvement:

 

1) Removed the brass plug from the base of the carburettor and poked out the petrol jet thereby revealed.

 

2) New petrol

 

3) Removed the whole carburetter in an attempt to see exactly how it works. Can't figure it out properly as I couldn't find a box spanner to remove the jet. Re-fitted it to the engine.

 

3) Disconnected the plug lead to check if a spark jumps to the cylinder head whn the magneto earth cable is removed from it's parking peg. It does. A seriously big fat blue spark!

 

4) Removed the Champion D21 spark plug to find it looks in good order but is jet black in colour, being covered in what appears to be a very thin layer of soot. I've order a new one from Cafco as they don't seem to stock Champion D21 plugs. (Is that actually the right plug to use, or doesn't it really matter, as long as it fits?)

 

 

So now my questions:

 

Does the board think this is a fuel problem or an ignition problem?

 

Does anyone have a diagram of how the carb is designed/constructed?

 

How do magnetos fail? Mine appears to occasionally fail to spark when tested as above but this could just be because the 1/4" gap I was letting it spark across was too big.

 

My magneto delivers a spark on every TDC, exhaust strokes included. Is that right?

 

 

All comments and advice most welcome!

 

Many thanks,

Mike

Edited April 4, 2011 by Mike the Boilerman

[koukouvagia]

The K1 used to start beautifully initially and very easily by hand. This has all changed now. It has been getting progressively more difficult to start until to the point came when when hand-starting was no longer possible because it just won't fire on petrol reliably and consistently. I always have to use the electric start.

 

 

Hi Mike,

 

This sounds familiar.

 

I suspect, after you've done all the sensible things to eliminate petrol problems, that it's the magneto. The fact that you've got a nice fat spark when the plug's disconnected doesn't necessarily point to a healthy magneto.

 

I presume the points are set correctly and cleaned? Also what's the state of the HT lead? I seem to remember someone (was it Richard?) posting to say that modern HT lead was not suitable.

 

After progressive deterioration with starting on my K2 I had the magneto reconditioned. In the meantime I adapted a spare magneto to coil and battery ignition. This is so successful that I'm not going to replace the reconditioned magneto but keep it as a spare.

 

Just a thought. Is the magneto timing OK? What kind of magneto is it?

Edited April 4, 2011 by koukouvagia

[MtB]

Hello KK,

 

Thanks for your reply.

 

Hi Mike,

 

This sounds familiar.

 

I suspect, after you've done all the sensible things to eliminate petrol problems, that it's the magneto. The fact that you've got a nice fat spark when the plug's disconnected doesn't necessarily point to a healthy magneto.

 

 

Really? How can that be, I wonder? Intuitively I'd have thought a spark was a spark was a spark.

 

I have one of those neon indicator lamps that go in the spark lead to give a visual indication that a real discharge is still happening from the spark source. I've just found it amongst my old car tools so I'll try it at the same time as I fit the new spark plug. I suspect it could yet turn out to be the spark discharge is present but tracking through the dirt on the old plug and failing to ignite the petrol vapour.

 

 

I presume the points are set correctly and cleaned?

 

I don't know. I have not looked at the points yet, having assumed the Big Fat Spark says they are fine. Assumption is the mother of all cock-ups I've already learned in the boiler-fixing business!

 

 

Also what's the state of the HT lead? I seem to remember someone (was it Richard?) posting to say that modern HT lead was not suitable.

 

I haven't examined it carefully but it worked fine last autumn. It 'looks' like an old style copper-cored lead. This engine was built/restored by Ken Salmon who is a well-known magneto restoration specialist so I think the lead is probably correct, but I'll check.

 

 

After progressive deterioration with starting on my K2 I had the magneto reconditioned. In the meantime I adapted a spare magneto to coil and battery ignition. This is so successful that I'm not going to replace the reconditioned magneto but keep it as a spare.

 

I'm finding this quite an attractive option too but I like the idea of keeping the magneto working. It's a good method of fault diagnosis though.

 

 

Just a thought. Is the magneto timing OK? What kind of magneto is it?

 

I have the feeling the timing is slightly too advanced as once in a while the firing spins the engine backwards. This could be because there is a spark on the exhaust stroke though. But it should still not spin the engine backwards having thought about it. I'll retard the timing slightly. Doesn't explain why it was fine last season though. Timing doesn't generally change all by itself.

 

Its a Lucas SR1. I also have a spare I bought on eBay last year. I might try fitting that next.

 

The carb appears so simple it's hard to imagine anything going wrong other than a blocked jet. Is that another dodgy assumption?!

 

 

Mike

[Gibbo]

Really? How can that be, I wonder? Intuitively I'd have thought a spark was a spark was a spark.

 

I don't know anything about engines but I know a little bit about electricity. A spark is massively dependent upon the pressure. What just arcs at normal atmospheric pressure won't arc at all with an increase of just 25% of pressure. So what looks healthy with the plug in free air might be a real weak little feeble thing when under pressure in a cylinder.

[BEngo]

The K1 used to start beautifully initially and very easily by hand. This has all changed now. It has been getting progressively more difficult to start until to the point came when when hand-starting was no longer possible because it just won't fire on petrol reliably and consistently. I always have to use the electric start.

 

The problem has been a progressive deterioration, not a sudden change. A short while after I first acquired the engine I found I could no longer start it 100% reliably on my first attempt. Failure to fire on the second firing stroke was beginning to occur. It would usually start normally on my second or third attempt, but then it grew worse. It became quite difficult to hand start due to erratic and unpredictable/random firing so I resorted to using the starter motor. At first I put it down to the extremely cold weather but in March there was no improvement, so I began to suspect the old petrol I was using. I resolved to chuck away the remainder of my six-month-old petrol and get some new.

 

On Saturday I tried starting it with new petrol, fully expecting a major improvement in starting behaviour, but still no change. It has become worse in fact, so I definitely have a problem.

 

The engine fires on the first firing stroke perfectly but then misses on subsequent firing strokes and stops. Using the electric start eventually gets it running, firing occasionally and very randomly at first. After multiple re-starts it begins to run more steadily on alternative firing strokes i.e. firing once every four revolutions, running very slowly. Then after a minute or so of this it eventually improves and begins to fire regularly on every firing stroke so the engine speed rises to about 450 rpm, the petrol runs out and I can change over to diesel as normal.

 

 

Action taken so far, with no improvement:

 

1) Removed the brass plug from the base of the carburettor and poked out the petrol jet thereby revealed.

 

2) New petrol

 

3) Removed the whole carburetter in an attempt to see exactly how it works. Can't figure it out properly as I couldn't find a box spanner to remove the jet. Re-fitted it to the engine.

 

3) Disconnected the plug lead to check if a spark jumps to the cylinder head whn the magneto earth cable is removed from it's parking peg. It does. A seriously big fat blue spark!

 

4) Removed the Champion D21 spark plug to find it looks in good order but is jet black in colour, being covered in what appears to be a very thin layer of soot. I've order a new one from Cafco as they don't seem to stock Champion D21 plugs. (Is that actually the right plug to use, or doesn't it really matter, as long as it fits?)

 

 

So now my questions:

 

Does the board think this is a fuel problem or an ignition problem?

 

Does anyone have a diagram of how the carb is designed/constructed?

 

How do magnetos fail? Mine appears to occasionally fail to spark when tested as above but this could just be because the 1/4" gap I was letting it spark across was too big.

 

My magneto delivers a spark on every TDC, exhaust strokes included. Is that right?

 

 

All comments and advice most welcome!

 

Many thanks,

Mike

 

This sounds like a classic kelvin spark problem, usaually caused by a dirty plug but possibly as KK says by a magneto problem. The D21 or the more readily available D16 is not the best plug- get a K97F from the Geen Spark Plug company- a long reach thing with three electrodes which will be about £25! You do need to clean the plugs very often.

 

Make sure you have a proper copper spark plug lead (not carbon string) and a non-resistive (non-suppressed) plug cap as these are both things which make the mag have to work harder. Magnetos fail either because the secondary coil has gone open or short circuit or because the magnets have got tired. Usually its damp which causes insulation failure, internal sparks in the coil and then an open circuit.

 

In the meantime, you can try cleaning the D21 ( brass brush), check the gap, and then put it in the gas ring (or a blowlamp) until the cable end is too hot to hold. Set the engine up for a start, Stick the plug in quick and crank it over. If that doesn't fix the problem at least temporarily then you need a magneto rebuild- I would recommend www.magnetorepairs.com near Stroud. He is as good as the placee in Appledore and a lot better priced. Do first have a look at the points and try replacing the condenser in the magneto if the points are badly pitted- the SR gap should be 10-12 thou according to Lucas. The points and condenser are fairly common.

 

The magneto (and plug) should spark every TDC- see the handbook for comments on magnetos generally- some engines have an extra spark plug on the crankcase because a 4 or 6 cyl magneto is being used on a 2 or 3 cyl engine.

 

If heating the plug doesn't help it is worth checking that the front half of the impulse drive is fully secured to the gear- the drive is through a pin and these have been known to shear. When that happens the timing is very random, but there is a cracking spark.

 

The other thing worth checking is that there are no air leaks round the inlet pipe where it seats to the rocker covers although I don't think a weak mixture is the cause of your symptoms.

 

The carb is just about impossible to break if the jet is not blocked- there's nothing else in there. There is a special brass Kelvin box spanner for removing the jet, but an ordinary 5/16 BSF (I think) works OK, provided you modify it to stop the jet dropping through. Don't over tighten it.

 

Regards

 

N

Edited April 4, 2011 by BEngo

[rjasmith]

Mike,

 

Here's my two penn'orth although all that KK says is based on MUCH more experience of actually operating a K engine. I've only played with mine when it was on a trolley but I have also listened at the knees of Andy and John up in Glasgie for an hour or two!

 

First of all a spark is definitely NOT always a spark etc. At atmospheric pressure a spark gap will break down at a much lower voltage than when it is in pressurised air. I have an old spark plug sand blasting machine/tester. In test mode this machine allows the plug to be fired while screwed into a chamber with a thick glass window. The chamber can be pressurised from the same air compressor that feeds the separate sand blaster part and the plug is fed from an HT generator running off the mains. In this way the plugs qualities can be tested as if it was actually in a running engine.

 

Another thing about magnetos. Be very careful when you test it that you don't try for a spark that is too long. The longer the spark gap, the greater the voltage required to make the discharge begin. The magnetos winding insulation will only take so much and if you make it do too long a spark you could force a breakdown in the winding and end up needing a rewind!

 

Some mags have a safety internal spark gap that will discharge any overvoltages but I don't know if the SR1 has one. I also don't know if my Bosch FR4 has either so I try to be careful on this as well.

 

What gap is your plug set to? Try a bit smaller if it is set to the usual 25 thou. Try 15 thou which is what Seaward do (and also as a friend who ran vintage cars once told me). Seaward also seem to prefer the D-16 (but see below).

 

It was me that once mentioned HT leads but it sounds as though you have a proper copper wire cored one. Don't use the modern high resistance interference limiting cable as used on cars which has a carbon impregnated fibre core.

 

If you're looking to get a new plug (which I'm sure is going to sort it out) try to get one or two Champion K-97F. Extraordinary looking things and supposed to be just the thing for starting Kelvins (also good in old Fordson petrol/paraffin tractors!). These plugs are used in "sour gas" engines in the oil industry ie engines sometimes used to drive those nodding pumps at the top of a nearly exhausted oil well. The engines are made to run on the horrible gas coming up the well and if the plug is designed to cope with that it should also cope with the oily vapours it will inevitably be subjected to in a Kelvin!

 

Unfortunately they can be a bit difficult to source but have a Google and you should be lucky. Also try not to fall over at the price (typically £20!). I got 3 off a bloke selling them on eBay for £15 each so was rather chuffed with that. You used to be only able to get them in the USA and in boxes of 10 but they seem to be easier to get in UK now.

 

The carburetter is very simple indeed and I think you should try removing the jet completely once you've found the right socket or box spanner. I had a bit of dirt in mine when I collected it from Seaward. It was amusing watching Andy and John arguing about whether it was too lean or too rich. After I got home I found the bit of dirt but only after I'd got the jet out. Also presumably both your air inlet gauzes are clear of dust and muck?

 

Can't think of anything else!

 

Richard

 

Damn! BEngo can type much quicker than me!

Edited April 4, 2011 by rjasmith

[OptedOut]

When we had a J2 bad starting was nearly always due to the plug.

[Chalky]

I don't know anything about engines but I know a little bit about electricity. A spark is massively dependent upon the pressure. What just arcs at normal atmospheric pressure won't arc at all with an increase of just 25% of pressure. So what looks healthy with the plug in free air might be a real weak little feeble thing when under pressure in a cylinder.

On the MGF we used to use a 25KV coil for the standard engine but a 45KV coil on higher compression ones. Check the condensor / capacitor in the magneto. They can deteritate over time and break down leading to a poor spark. Also look for HV tracks - it doesn't take a lot of dirt or damp to cause a weak spark.

[dave moore]

Hi Mike

I'm a Kelvin user, not an expert engineer, but I encountered similar problems with our J3 several years ago. The first fix, successful at first, was to source some real 4 star petrol. This had a higher octane rating than modern unleaded. Difficulties resurfaced after a while and I replaced the plugs with some triple electrode ones recommended by Dick Goble, my main man for Kelvins. This was an improvement, but starting by motor was a pain at times, with a weak spark evident. Examining the magneto showed a crack in the rotor arm and a couple of teeth missing from the bakelite wheel. Despite Dick's help we were unable to source a spare. The magneto ended up at Russel Newberys in the care of Alastair Denyer (magneto guru) but the only option was to make a new wheel costing several hundred pounds. Subsequently we converted to glow plug start and I'm honestly not sorry to get petrol off the boat. D H Day are specialist magneto rebuilders in, I think, Dorset and quoted around £400 for the job. One day, when I've got the spare cash.....but if I did get it rebuilt I think I'd still use glow plugs as the general preferred starting method, with petrol for high days and holidays.

Cheers

Dave

[sociable_hermit]

Cleaning the spark plug with a plug brush (available from Halfrauds et al) sounds like the easiest and most cost-effective option to me, but I'm no Kelvin expert

[koukouvagia]

I've just come across this site – it has some good advice on the maintenance of Lucas magnetos.

[NB Alnwick]

I cannot add anything to what has been said already. The answer will be in there somewhere. In my years of experience with classic and vintage spark ignition engines, I have always following a simple checking procedure - it goes like this:

 

1. Spark plug(s)

2. Ignition leads

3. Ignition timing/contact breaker gap

4. Condenser (Capacitor)

5. Fuel supply/mixture

 

Note that fuel is usually the last thing I would check and plugs are always the first. As Gibbo said, pressure makes a huge difference to the spark, so my first action always is to change the plug for one that has been proven previously as clean and sound.

 

Finally, our engine is fitted with a Lucas Thermostart in the inlet manifold. Provided the diesel injection pump is properly set-up and the injection timing is spot on, it will always start on diesel so we don't bother with petrol start - except for the fun of it . . .

Edited April 4, 2011 by NB Alnwick

[NB Alnwick]

Another thought - magnetos repidly descend into an early grave if you allow them to spin without being being able to discharge through a decent spark plug. If the plug is dirty or if the gap is too wide (0.015" is ideal) it will not discharge effectively.

[Harpur Hill]

Hi

Whilst I have no experience of Kelvin engines I have had experience of many other makes.

 

I would guess this is almost certainly a plug related issue - when I was a lad (many years ago!) Champion plugs were well known to fail on motor cycles after being unused for some time. This was typically over winter but was also known to happen after just a week or so of standing. Never did find out why this happened and they may have improved over the intervening years but the memory remains.

 

From my more recent stationary engine experience a clean plug (and copper core lead) is essential and if it won't start try another plug first before delving into deeper issues.

 

May I also emphasise not to spin the mag without somewhere for the spark to go - it will have to get out somewhere and is often through the winding insulation - then it's megabucks.

 

If it helps I have a coil system ready made up from one of my more difficult stationary engines - you are welcome to it but not sure how it would get to you, I think you are in Reading & I'm near Sheffield.

 

Cheers

HH

[MtB]

Hello HH,

 

Hi

Whilst I have no experience of Kelvin engines I have had experience of many other makes.

 

I would guess this is almost certainly a plug related issue - when I was a lad (many years ago!) Champion plugs were well known to fail on motor cycles after being unused for some time. This was typically over winter but was also known to happen after just a week or so of standing. Never did find out why this happened and they may have improved over the intervening years but the memory remains.

 

Well you were dead right. I fitted a plain new NGK equivalent of a Champion D21 with the gap shut down to about 12 thou and the engine started first swing by hand just as beautifully as it always used to! So thanks to everyone who said 'spark plug'! I've also ordered a K97F triple spark plug from eBay which I'll fit at the next hint of reluctance to fire but I'm not convinced this will be necessary given BEngo's (and others) comments about needing to clean the plug regularly. Just how do you clean a spark plug anyway? I'm more inclined to buy a few cheap D21s (or NGK equivs) for stock and treat them as consumables should the K97F play up. Or maybe the soot on the old plug was not the problem. My engine certainly sits unused for weeks on end sometimes, and has done through the winter and the plug deteriorated as you describe.

 

 

From my more recent stationary engine experience a clean plug (and copper core lead) is essential and if it won't start try another plug first before delving into deeper issues.

 

I checked as as I expected, I have a copper core plug lead. It's not single core, it's multi-strand. Hard to count the strands in the crimped tag on the end but looks like about seven strands.

 

 

May I also emphasise not to spin the mag without somewhere for the spark to go - it will have to get out somewhere and is often through the winding insulation - then it's megabucks.

 

I suspect this may also be a problem. Even thought the engine starts dead easily again, once it has run up to speed it still seems to fire a little irregularly but it's hard to tell. The firing strokes on petrol are quite muffled and maybe some variation in the sound of them is normal. I'll try replacing the contact breaker and condenser in the magneto next and see if that makes any difference.

 

 

If it helps I have a coil system ready made up from one of my more difficult stationary engines - you are welcome to it but not sure how it would get to you, I think you are in Reading & I'm near Sheffield.

 

Very kind of you to offer! Thank you. You're right about me being it Reading but if I find myself near Sheffield in the foreseeable I'll PM you but this may not be anytime soon.

 

 

And Dave Moore mentioned trying some real Four Star petrol. Interesting because the peeps I bought the engine from were adamant I would need this. They said it won't start on unleaded. I tried it on regular unleaded and it was fine for me! But maybe the plug sooting is the result. The old plug is clearly REALLY old so I think the plug-sooting problem may be a recent development.

 

Thanks to everyone who has contributed.

 

Mike

[sociable_hermit]

Just how do you clean a spark plug anyway?

As mentioned before, you can buy a "plug brush" from any half decent motor factors. It's essentially a very soft wire brush that won't damage the plug.

 

It was a regular job on my classic Alfa as I could never get exactly the right size idle jets, so it always ran a bit rich. By 'regular job' I mean about once a fortnight! If you've managed without so far, you've done well.

[Harpur Hill]

Hi

Happy to help, glad you got it sorted.

 

Yes, NGK brings back memories,we used to seek these out and pretty much any plug except Champion as they did not seem to fail in the same way.

 

Clean plugs with a wire brush, you can get toothbrush sized brass ones at around 3 for £1 at street markets, cheapo shops etc; useful for all sorts of jobs & cheap enough to be disposable (unless like me you are from Yorkshire!)

 

Cheers

HH

[WotEver]

As mentioned before, you can buy a "plug brush" from any half decent motor factors. It's essentially a very soft wire brush that won't damage the plug.

Also look around in car boot sales for a plug grit blaster. These were quite popular in the 70's; they ran off 12V and threw grit up at the plug which you pushed through a small hole in the top. I seem to recall Halfords sold them for less than a tenner so if you come across one which works (and has some grit) it might be a fun purchase. I used to have one, but I lent it out once...

 

Tony

[MtB]

As mentioned before, you can buy a "plug brush" from any half decent motor factors. It's essentially a very soft wire brush that won't damage the plug.

 

It was a regular job on my classic Alfa as I could never get exactly the right size idle jets, so it always ran a bit rich. By 'regular job' I mean about once a fortnight! If you've managed without so far, you've done well.

 

 

Ah yes I looked at those and I have bought a few in my time. Never found you can clean any further than the bits around the elctrode. No chance of reaching inside with a brass wire brush and cleaning the ceramic insulation sleeve of the centre electrode where the spark tracking occurs. Or IS there a technique for this I haven't figured out?

 

Mike

[larkshall]

Spark plug can be cleaned with wire brush, and a piece of glass paper. Don't forget to re-gap the plug points (typically 20 to 25 thou on this type of application.

 

Put plug in its cap and lean plug side on engine. Give the motor a swing with ignition on. You should see a spark. (If the light is very bright you night not see a faint spark. Cheat, put a tiny drop of petrol on plug tip and swing motor again. if plug etc ok you should have a tiny flame for a second)

 

Now even if this is ok, it does not mean that the spark plug will spark in the engine when under pressure, in fact this problem is quite common.

 

HT Lead will be 5 or 7 core, or very unusually carbon cored.

 

If the plug lead has a suppressor cap this is another point of failure.

 

4 star v unleaded. 4 (genuine), will smoke more than unleaded. I can still get genuine 4 star here as well as LRP . Incidently as far as starting problems are concerned, either/or makes no difference.

 

Oh cleaning interior plug electrode is usually done with a grit blaster Gunson's make one I believe.

 

Irregular running on petrol... Not uncommon, check magneto points, and condenser. Check contact points heal is smooth, and lightly greased. Ditto the mounting pin. If the magneto hasn't been rebuilt check for play in the shaft bearings. ditto auto advance/retard springs.

 

Reminds me of the smell of TVO

Edited April 8, 2011 by larkshall

[Harpur Hill]

Hi

It helps if you stick your tongue out of the corner of your mouth & then just persevere.

 

Cheers

HH

[RLWP]

<snip>

 

you can get toothbrush sized brass ones at around 3 for £1 at street markets, cheapo shops etc;

 

<snip>

 

HH

 

I've stopped buying those brushes as they typically have eleven bristles of brass-coated steel wire each. Half of the bristles fall out the first time you use them (and half of those stick in your thumb).

 

My two plastic handled ones bought thirty years ago are still going strong

 

Richard

[rjasmith]

Ah yes I looked at those and I have bought a few in my time. Never found you can clean any further than the bits around the elctrode. No chance of reaching inside with a brass wire brush and cleaning the ceramic insulation sleeve of the centre electrode where the spark tracking occurs. Or IS there a technique for this I haven't figured out?

 

Mike

 

Mike,

 

Thats where a grit blaster comes in! I really must get the one a friend gave me working. Then I could offer a Kelvin owners plug "deep cleaning" and testing service!

 

Not a priority to do this yet though.

 

Must get on with the boat!

 

Richard

[WotEver]

Also look around in car boot sales for a plug grit blaster. These were quite popular in the 70's; they ran off 12V and threw grit up at the plug which you pushed through a small hole in the top. I seem to recall Halfords sold them for less than a tenner so if you come across one which works (and has some grit) it might be a fun purchase. I used to have one, but I lent it out once...

 

Tony

Here's on on Ebay: http://cgi.ebay.com/ebaymotors/Black-Decker-Spark-Plug-Cleaner-Kit-12-Volt-_W0QQcmdZViewItemQQitemZ150587027938QQptZVintageQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

It's in the US though

 

Tony

 

It helps if you stick your tongue out of the corner of your mouth & then just persevere.

I thought that was for painting straight lines...

 

Tony

[Albion]

Mike,

 

Thats where a grit blaster comes in! I really must get the one a friend gave me working. Then I could offer a Kelvin owners plug "deep cleaning" and testing service!

 

Not a priority to do this yet though.

 

Must get on with the boat!

 

Richard

 

Yep when I closed my garage business down a few years ago to retire I threw away a Champion professional grit blasting machine run from the air line. It was the one where you could also screw the plug into the windowed chamber and increase the airline pressure until the spark failed and use that to judge the condition of the plug depending on gap. We hadn't used it professionally for years with the modern type of car that we were working on.

Never thought I'd ever see anyone want one again

The carbon build up is due to a rich mixture and, unfortunately, as carbon is a good conductor of electricity it causes the spark to leak to earth rather than jumping the gap. I'm not convinced that those spark plug brushes are any good to be honest. I have heard of people burning the carbon off the tip of the plug in a gas flame but I've never done it so I can't comment on its efficacy.

Roger