Tilley X246B cock and pricker wire questions

Hi all,

I've been fettling again this evening, and have had to scrap two Tilley cocks due to the same fault - failure to shut off the fuel flow. I think the crank bearings must be badly worn, to the extent that the spring pressure from the vapouriser holds the fuel valve open slightly, even when the cock is turned fully off.

I've also got a suspect vapouriser where the pricker wire doesn't quite poke through the jet orifice when the cock is turned off. On close inspection I find that the brass sleeve has come loose from the bottom of the pricker wire itself. Can anyone tell me if there is a recommended procedure for refixing this?

I could soft-solder the sleeve onto the wire, but its position must be critical in order to enable the pricker to go just the right distance through the jet. I'm tempted to measure carefully the length of the pricker wire from a known good working vapouriser, and solder the sleeve on to the wire in the exact position - difficult, I know. Alternatively, just solder the sleeve to the wire then file down the end by trial and error?

I know that new vapourisers are not expensive, but I'd get more satisfaction from fixing this dodgy one! Any advice from the more experienced fettlers out there will be welcome.

Phil

 

Hello Phil, what period of control cocks are they?

Is the point still okay on the vapouriser's pricker wire?

Which type of bottom end is on the vapouriser, is made from brass or steel?

The sleeve which fits onto the bottom end of the pricker wire can be crimped on with a pair of pliers, Jeff.

 

Hi Jeff, some good questions there. These are quite recent cocks, from lamps date stamped 1978.

The bottom end of the vapouriser is steel. The point of the pricker wire appears to be OK. The sleeve has two tiny holes drilled in it from one side only. I was worried about crimping it with pliers in case it went 'oval' and became a tight fit in the guide tube, but I'll try that first.

Many thanks for the info,

Phil

 

Hi Phil, I recall that there has been much dicussion in the past about Tilley Control cocks. If I remember correctly, the control is not meant to be a shut-off valve, but more of a cleaning device that will only shut off at the vap tube jet when the needle point is lifted to seal it. Do not expect a control cock to comletely seal off the pressure without a vap tube. Steve.

 

So, does that mean there is no point replacing the pip in the control cock?

Saves on PIP's

 

Hi Phil if the cock pip seal is ok,i may have misread the post but,the cock also has a rubber seal pip,the same as the pump.
If it has been replaced then your theory on the crank bearing is most likely corect.
The newer alluminium cocks were not as good as the older brass cocks as on the guardsman 246 or of that period.
On the other Question regarding the vapouriser wire,as Jeff said is the vapouriser wire still got its tip on,as these could become worn and were once sold seperate,base camp i beleive still stock them.
Brian you dont need to have to replace the pip on a Tilley cock.
As long as you do not start pressureising the lantern, untill it is fully preheated,and to turn it off you will have to loosen the pump to depressureise it which is the best way to turn the lamp off.

 

In my experience the control cock valve works quite well keeping the pressure inside the tank especially when you take the extinguished lamp from one place to another.

Nevertheless I wouldn't trust the valve to keep the high pressure over a longer period.

Mostly I use it to seal the unpressurized tank so that no fuel can accidentally get out of it. I close the valve and the filler cap/pump and the lamp is ready to get carried around.

One thing to pay attention for is to open the filler cap/pump first to release pressure that might have build up due to temperature changes, else the fuel will come out of the vap and spill paraffin around.

 

When I restore a Tilley control cock, I replace all of the seals and washers and I do not use the aluminium control cocks.

When Tilley introduced the push on knob for the control cock back in the 1960s, that was the beginning of the end of a fine piece of kit.

 

To quote from Jim Dick's book, page 20: "...an improved control cock was patented in 1924. This provided a means of both operating the cleaning wire and shutting off the supply of fuel to the burner..." A glance at the patent drawing shows the rubber washer forming the shut-off valve in the cock, which is a separate spring-loaded shaped rubber washer in the current design of cock, but as far as I can see it is clearly intended to close off the fuel supply.

I have six of these lamps, four of which shut off perfectly tight and two which don't, and they all have new 'pips'. I believe the cock, and not the pricker wire, is the design point of fuel shut-off, for the following reasons.

Tilley's own lighting instructions state "...give 10/15 strokes of the pump..." before igniting the spirit pre-heater torch. Unless the cock provided tight fuel shut-off against this tank pressure, fuel would rise up the vapouriser immediately and cause the well-known and undesirable flaring. This is exactly what happens with a worn cock.

When pre-heating, the vapouriser could be full of air, full of liquid fuel, or anything in between. Therefore the pricker wire cannot, by definition, be designed to provide tight shut-off at the jet, as this could cause excess pressure inside the vapouriser during pre-heating. My experience is that small quantities of vapour do leave the jet during pre-heating, even with the pricker wire fully raised, as the vapouriser heats up and liquid fuel inside it evaporates, and this vapour can be seen intermittently burning inside the mantle during pre-heating.

Finally, Tilley's instructions say "...the lamp may be extinguished by turning the control knob into the 'off' position. There is no need to release pressure from the container..." which in my opinion is proof that the cock was designed to provide tight shut-off. The tightness of the seal will increase to an extent with tank pressure, as the inside of the vapouriser will be at atmospheric pressure, even with the pricker wire raised. I have a Guardsman that holds full tank pressure indefinitely, which I only discovered when I forgot to release the air and found it still indicating full pressure three days later!

I agree with Jeff that the aluminium-bodied cock can only be inferior to the earlier brass one. I have demonstrated by experiment that even a worn aluminium cock provides tight shut-off of fuel with no vapouriser in place, but when the vapouriser is screwed in, the spring pressure acting on the pricker wire forces the internal crank downwards, to the extent that the fuel valve pin presses against the rubber washer and pushes it off it seat, which allows a dribble of fuel to flow. In practice, this makes lighting difficult, and extinguishing the lamp has to be done by releasing the tank pressure, which should not be necessary according to Tilley's instructions.

For what it's worth, the two worn cocks in my possession demonstrate a much greater degree of spindle 'looseness' than the good working cocks. However I've retrieved these items from the bin in case anyone knows how to repair them!

Phil

 

Hi Phil,

I understand the theory, but in practice the control cock as a shut-off valve seldom worked. There are reams of discussion on this subject, and all I accept now is that I personally do not expect any Tilley Control Cock to completely shut off the fuel pressure. Design aim is one thing, achieving it is another. Ain't lamps interesting? Best regards - Steve.

 

I would say from Tilley's point of view, shutting the lamp off by means of the control cock is an excellent idea. You end up with an over sized jet and therefore a knackered vapouriser so who do you turn to for a replacement. I rarely change the pip in the control cock as I see it as a spare NRV seal which is a far more important piece of kit. If the cock doesn't seal then I light the lamp using the (see page 4) and always extinguish by releasing the pressure. Just my two pence. Best regards Matt.

 

Hello Phil, I strip the aluminium control cocks, to get the 2 gland nut washers and the spring and the pip, some of the older aluminium ones still used a round pip in a holder, so those round pips are very useful.

I like to restore the old brass control cocks properly and I can only recall one leaking after I had restored it.

The gland nut washer failed after years of use and once I fitted a new washer it was fine, Jeff.

 

...and I expect you take the aluminium bodies to the scrapyard for recycling, Jeff - you get a good price for scrap aluminium these days!

IIRC, didn't Tilley patent the shaped pricker wire that sealed the jet, sometime in the 1930s. That was what caused the ruck between them and Willis & Bates later on. That led Tilley taking W&B to court for breach of copyright. W&B won their case.

In practice, the control cock seal is pointless on a kero lamptern and the Tilley one is rarely replaced when it begins to leak because it just doesn't show.

Somehow, I thought Tilley discontinued fitting the lower seal, beginning with the aluminium control cocks. Could be wrong there, mind...

 

Were is the second gland nut washer?

I thought there was just one.

Many thanks.

 

According to Tilley, you should fit two together on the control cock shaft.

I never have fitted two and I don't think I've ever had a lantern come to me with two fitted. One seal seems to work quite nicely and I've never had a problem...

 

Hello Phil, the aluminium control cocks have 2 gland washers fitted or one extra thick washer, Jeff.

Hello David, very good!

The aluminiun control cocks still have the lower seal, Jeff.

 

I have come across single and double spindle seals fitted to these cocks. The single seals are of square cross-section whereas the dual seals are more like tiny o-rings of circular cross-section.

I think as long as the seal remains flexible the actual number doesn't matter too much.

 

I think you are correct in that observation Phil. Steve.

 

I thought the Fettle Box man was being kind or had shakky fingers when he prepared the kit and I got 2 gland seals in it.

All explained now.

thanks

 

You definitely get two 234 gland seals in the SP1 service pack. Can't remember about the 498/old 498 packs...

 

Whenever I fettle a Tilley control cock, I first polish the spindle lightly with Brasso to remove any roughness, then apply a smear of Vaseline all along the spindle which helps the new o-rings slide into place, prevents scoring and lubricates the rotating metal/rubber interface. I've had a 100% success rate so far with this method.

To my mind, the control cock seal is a weak point in the Tilley design (some say there may be others...!) although it's only a simple packing gland that has to hold back paraffin at 30 psi. I anticipate that the new Viton o-rings I bought from the Fettle Box will remain supple and last longer than the neoprene or whatever originals from Tilley.

Phil

 

Yep you get two in the old 498 kit. One has always worked for me though.

 

I generally can't be arsed with fiddly O rings and use Teflon string to pack Tilley glands. ::Neil::