Great War truck Posted January 29, 2013 Author Share Posted January 29, 2013 Finally, it remained only to secure the shorter arms to the shaft. These were done by first cross-drilling and then reaming using a taper pin reamer in a tap wrench before knocking in the taper pins. All of these components must be assembled in-situ so the pins have been left over-length for the time being. Hopefully, the whole mechanism can be assembled the next time we have a get-together. Quote Link to comment Share on other sites More sharing options...
Asciidv Posted January 30, 2013 Share Posted January 30, 2013 Steve, When you have the time, I am sure that many of us would like to know your experience with silver soldering/brazing. Do you use the same rod type all the time or do you select a rod depending on the strength of joint that you require? Do you find the flow characteristics of different rods and flux types influences what you use? What combination do you normally use and does it differ for ferrous and non-ferrous parts? Barry. Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted January 31, 2013 Share Posted January 31, 2013 (edited) Steve, When you have the time, I am sure that many of us would like to know your experience with silver soldering/brazing. Do you use the same rod type all the time or do you select a rod depending on the strength of joint that you require? Do you find the flow characteristics of different rods and flux types influences what you use? What combination do you normally use and does it differ for ferrous and non-ferrous parts? Barry. I guess that Steve will not have picked this one up yet, Barry - so perhaps I can have a go and he can come in later when he reads it! All of our silver soldering and brazing experience really stems from our Model Engineering activities - and the construction of miniature steam locomotives in particular, and especially their copper boilers and boiler fittings. So much we have learned from reading and picking the brains of others who have had the experience and where we have learned from our own mistakes!. We have only ever used propane as a source of heat - the copper boiler on our narrow gauge loco was heated sufficiently - out of doors - with three propane torches on it which did the job admirably. We are about two thirds through with the construction of a similar size copper boiler for a narrow gauge Koppel - about 6 or 7 inches in boiler diameter with a loco type firebox - when it was put aside in favour of the lorries - I hope to pick it up again one day! This was heated up with just one big propane torch but it was well bricked up to conserve the heat and that worked - although now I think we were brave to take that on with just the one torch! The professionals seem to use oxy-acetylene but we are not so equipped and have never used that. Our favourite silver solder has been Easyflo No2- cleanliness and de-greasing of the items to be put together and a suitable flux is essential for a sound joint. I still have a reasonable stock of the original Easyflo No 2 which had cadmium included in it which seemed to aid easy use of it - but cadmium has now been banned from inclusion in this and the equivalent silver solder now is cadmium free. It is made by Johnson Matthey and they provide a flux suitable for use with it which comes in powder form and has to be mixed into a cream consistency before use. Just mix up sufficient for your immediate use. The problem that can be encountered with multiple heatings of the same item is that there is a danger of earlier silver soldered joints on the same item melting and coming apart again - various silver solders are available with different melting points and it has been advocated that if you are doing multiple heatings of the same item so that you can attach other bits to it, then you use a silver solder with the highest melting temperature first of all so that for subsequent heatings, you do not have to take the temperature quite so high to get the silver solder to "flash over". I understand that the melting temperature of Easyflo No 2 is higher on a second heating of the same joint so you do have a small safety margin there. However, I find that with a bit of care, the same solder - Easyflo No.2 can still be used for subsequent brazing on the same item - but make sure that any earlier silver soldered joints on that object are well fluxed up again. This is what I did on the two small assemblies for the Governor weights and pivot - when those two assemblies were put together, they were in such close proximity that there was certainly a danger of the earlier silver soldered joints coming apart again! We have used this same method on brass, bronzes, copper and steel and have had no problems. We have found it to be a great method of attaching bits! I am sure that others reading this will have had more experience than us and I shall be pleased to read any other contributions and have the benefit of their experience! Tony Edited February 1, 2013 by Minesweeper Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted January 31, 2013 Share Posted January 31, 2013 Thanks for that. Never used the process myself. I did note in the images above that the cotter pin is straining the soldered joint, so I'm assuming it has considerable strength. While I couldn't do the detail work I would certainly just have welded the two components together if it was going to resist a cotter pin, but I remember the same technique all over the Dennis and it seems to work nicely. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted January 31, 2013 Author Share Posted January 31, 2013 There was not a Timing Pointer remaining on either of the engines when we got them but we shall require it when we want to set our engine up. We found a picture of one within our photograph collection on another Thorny engine and this coupled with a tiny picture of one in the Parts Book has given us sufficient information to dimension it and sketch one out. A piece of 14 Gauge mild steel found in the Scrap Box provided the material – the Arrow was cut out from this and bent up. The Arrow is actually bolted down under the retaining nuts of the front cylinder block but as this not yet fitted, there has been some guess work on the amount of the bends put in it – these may well have to be adjusted when the Block is finally fitted and bolted down. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted February 4, 2013 Author Share Posted February 4, 2013 The valves have arrived, from G & S valves of Godalming. They fit beautifully and we are very pleased. One more step forward! Quote Link to comment Share on other sites More sharing options...
Ian L Posted February 5, 2013 Share Posted February 5, 2013 I guess that Steve will not have picked this one up yet, Barry - so perhaps I can have a go and he can come in later when he reads it! All of our silver soldering and brazing experience really stems from our Model Engineering activities - and the construction of miniature steam locomotives in particular, and especially their copper boilers and boiler fittings. So much we have learned from reading and picking the brains of others who have had the experience and where we have learned from our own mistakes!. We have only ever used propane as a source of heat - the copper boiler on our narrow gauge loco was heated sufficiently - out of doors - with three propane torches on it which did the job admirably. We are about two thirds through with the construction of a similar size copper boiler for a narrow gauge Koppel - about 6 or 7 inches in boiler diameter with a loco type firebox - when it was put aside in favour of the lorries - I hope to pick it up again one day! This was heated up with just one big propane torch but it was well bricked up to conserve the heat and that worked - although now I think we were brave to take that on with just the one torch! The professionals seem to use oxy-acetylene but we are not so equipped and have never used that. Our favourite silver solder has been Easyflo No2- cleanliness and de-greasing of the items to be put together and a suitable flux is essential for a sound joint. I still have a reasonable stock of the original Easyflo No 2 which had cadmium included in it which seemed to aid easy use of it - but cadmium has now been banned from inclusion in this and the equivalent silver solder now is cadmium free. It is made by Johnson Matthey and they provide a flux suitable for use with it which comes in powder form and has to be mixed into a cream consistency before use. Just mix up sufficient for your immediate use. The problem that can be encountered with multiple heatings of the same item is that there is a danger of earlier silver soldered joints on the same item melting and coming apart again - various silver solders are available with different melting points and it has been advocated that if you are doing multiple heatings of the same item so that you can attach other bits to it, then you use a silver solder with the highest melting temperature first of all so that for subsequent heatings, you do not have to take the temperature quite so high to get the silver solder to "flash over". I understand that the melting temperature of Easyflo No 2 is higher on a second heating of the same joint so you do have a small safety margin there. However, I find that with a bit of care, the same solder - Easyflo No.2 can still be used for subsequent brazing on the same item - but make sure that any earlier silver soldered joints on that object are well fluxed up again. This is what I did on the two small assemblies for the Governor weights and pivot - when those two assemblies were put together, they were in such close proximity that there was certainly a danger of the earlier silver soldered joints coming apart again! We have used this same method on brass, bronzes, copper and steel and have had no problems. We have found it to be a great method of attaching bits! I am sure that others reading this will have had more experience than us and I shall be pleased to read any other contributions and have the benefit of their experience! Tony Very interesting Tony & just at the right time. I am about to start silver soldering some brass 'plumbing' on my Water Bowser Restoration but was not sure what silver solder to use ? but now I'm going to try Easyflo No.2 Thanks. Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted February 5, 2013 Share Posted February 5, 2013 Very interesting Tony & just at the right time. I am about to start silver soldering some brass 'plumbing' on my Water Bowser Restoration but was not sure what silver solder to use ? but now I'm going to try Easyflo No.2 Thanks. Good luck, Ian! Remember cleanliness is essential - get any oxidation off the bits to be joined first of all and do not touch the joining areas with your fingers again after you have cleaned them - grease from your fingers can upset the apple cart - make sure that you have "bright" metal. Silver solder "flashes over" very easily so anywhere the flux goes around your joint, the silver solder will run. So enough flux - but try to keep it on the areas to be joined. Practice on a couple of bits of scrap first of all - you want the solder to run by getting it hot enough from the work piece rather than melting it in the flame! Tony Quote Link to comment Share on other sites More sharing options...
paul.norton Posted February 5, 2013 Share Posted February 5, 2013 Tony I read somewhere long ago, that if a little washing-up liquid is stirred in with the flux it will help with keeping the surfaces clean. I have never tried it. Have you? Regards Paul Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted February 5, 2013 Share Posted February 5, 2013 Tony I read somewhere long ago, that if a little washing-up liquid is stirred in with the flux it will help with keeping the surfaces clean. I have never tried it. Have you? Regards Paul Never tried that one! Tony Quote Link to comment Share on other sites More sharing options...
Great War truck Posted February 5, 2013 Author Share Posted February 5, 2013 We had a trip to Devon at the weekend and thought we would have a look at the valve timing. As mentioned before, the gears are a matched set from the same engine. However, we didn’t think to check that the keyway in the crank pinion was in the same place as that in the original one, so the camshaft could be way out! Unfortunately, we don’t have a timing chart for the Thorny but the one for the Dennis shows that the exhaust valves should start to lift at 49° before bottom dead centre. To check this, we first fitted Father’s nice new timing pointer. We then identified TDC by clamping a flat strip to the side of the crank and setting the angle using a square. This position was marked on the flywheel with a felt pen. Finally, we placed a clock gauge on top of one of the push rods to see when it began to move. Steve slowly turned the flywheel to see what happened. The valve will begin to lift once the tappet clearance is taken up so this had to be allowed for. The manual states that ‘the tappets are adjustable and great care must be taken to set the correct gap’. However, it doesn’t say what the gap should be! The instruction plate on the end of the tank says that it should be ‘the thickness of a good quality visiting card’ but Captain S Bramley-Moore M.C writes in Motors in a Nutshell. that it should be ‘the thickness of the flap of a gummed manilla envelope’. We assumed a figure of 0.015” as that is the dimension specified for the Dennis. The tappet began to lift and at 0.015”, we stopped and checked the angle. It was 42° before BDC which was a bit later than we had hoped. Captain Bramley Moore states in his book that the average angle of the fifteen makes of lorry he has looked at is 47° so we stopped the flywheel at that position to see how far the push rod had lifted. It was 0.012”. Now we would like some opinions please. This feels a little tight for a tappet clearance so what is the concensus please? Can we run safely with a clearance of 0.012”, set when hot? The timing pinion has 29 teeth so we can only increment the camshafts in a little over 12° steps. Any finer adjustment would require my removing the pinion and cutting a new keyway at a carefully calculated location. At the moment, our feeling is just to try it. Does anyone have any strong views please? Quote Link to comment Share on other sites More sharing options...
Gordon_M Posted February 5, 2013 Share Posted February 5, 2013 You are absolutely right, just build it and try it. It's not like you will be running it with a full load, and the higher octane fuel will affect it too. Worst case you'll be machining a stepped key, rather than reworking any original parts. Quote Link to comment Share on other sites More sharing options...
Degsy Posted February 5, 2013 Share Posted February 5, 2013 Having done a bit of Googling and found evidence of older engines with tappet clearances as low as 6 thou I agree with Gordon that it is a case of suck it and see unless, of course, you can find somebody with written info or a Thorny engine in running order. Quote Link to comment Share on other sites More sharing options...
David Herbert Posted February 5, 2013 Share Posted February 5, 2013 Your method of establishing TDC assumes that the cylinder C/L goes through the crank C/L. On older engines it was not uncommon for the cylinder to be offset a bit so that the force of combustion pressed more verticaly on the crank, reducing side thrust on the piston. The forces on the compression stroke were much less so a compromise could be made. An offset would make a difference to TDC as the crank would need to be turned towards the cylinder so that a line drawn through the crankshaft C/L, through the crank C/L and through the gugeon pin C/L was straight. Not a big difference but measurable. Idealy of course you put a depth stop through a spark plug hole and turn the crank either way till the piston comes up and meets the stop. Mark both the stop points on the flywheel and half way between is TDC. However this will be a little hard in this case! It seems to me that with the changes to compression ratio from the different bore, better fits of valves and pistons and better petrol, any original specs are not going to be ideal anyway. To a large extent you will be able to compensate with the ign timing anyway. It is nice to see the project moving forward, I think your public feel involved as we are treated to a bolt by bolt account rather than "this is what I started with, here it is done". Thank you for the considerable time that must go into posting each new development. David Quote Link to comment Share on other sites More sharing options...
Old Bill Posted February 5, 2013 Share Posted February 5, 2013 Your method of establishing TDC assumes that the cylinder C/L goes through the crank C/L. On older engines it was not uncommon for the cylinder to be offset a bit so that the force of combustion pressed more verticaly on the crank, reducing side thrust on the piston. The forces on the compression stroke were much less so a compromise could be made. Gosh, thank you David. I had forgotten that they did that sort of thing and didn't give it a thought! I will check. Thank you for your kind comments as well. We are always a bit concerned about going into mind numbing detail. However, we do hope that our friends might occasionally find a good tip. Better still is when someone says 'don't do it like that, do it like this. Much easier'! Steve Quote Link to comment Share on other sites More sharing options...
mtskull Posted February 5, 2013 Share Posted February 5, 2013 If you are setting the valve clearances hot, then 12 thou. will be plenty. The danger lies in setting too tight a clearance when cold, in which case you run the risk of the gaps closing up when hot, resulting in burned valves and seats. Magnificent work, by the way; I have been following this thread for some time and am amazed at the skill and ingenuity shown by your team.:bow: Quote Link to comment Share on other sites More sharing options...
Barney Posted February 5, 2013 Share Posted February 5, 2013 Firstly, congratulations are in order for the families fabulous engineering skills in remaking the governor mechanism. Secondly, with regard to the valve timing issue. I have an old book that gives the valve timing data of a number of petrol engines. In the larger engine sizes there are a fair range of values depending on the individual engine; unfortunately no Thornycroft engines are listed. Looking down the list of engines I find that the valve timings fall within the following ranges ---- Inlet valves open at between 5 and 10 degs Before Top Dead Centre and close at between 40 and 50 degs After Bottom Dead Centre. Exhaust valves open at between 40 and 50 degs Before Bottom Dead Centre and close at between 10 and 15 degs After Top Dead Centre. If the timing on your engine falls somewhere within the above ranges I don’t think that it will make very much difference to its performance even if the timing is not exactly as recommended by Thornycroft. I once owned an Austin Healy Sprite where the camshaft was out by one tooth of the camshaft chain sprocket and once corrected I can’t say that I noticed any difference to the cars performance during normal urban driving. It would, I think, have been noticeable on a race track but then I only brought the Sprite to impress the girl friend. I might add that the ignition timing was correct even though the valve timing was wrong. Tappet clearances; I think 12 thou hot should be OK for your engine. Most older engines are set within the range of 10 to 15 thou. If you increase the clearance beyond 15 thou. you will get a lot of clatter and rapid wear of the tappet/valve faces will occur. Best wishes. John Quote Link to comment Share on other sites More sharing options...
gritineye Posted February 6, 2013 Share Posted February 6, 2013 We are always a bit concerned about going into mind numbing detail. Steve, what you call mind numbing is actually mind expanding to us sitting at home, it allows us to properly cogitate the problems knowing all the relevant facts have been revealed, so when the next installment appears we are right there with you and can nod sagely or wow in admiration, whichever is appropriate! :bow::thanx: Bernard Quote Link to comment Share on other sites More sharing options...
Asciidv Posted February 6, 2013 Share Posted February 6, 2013 (edited) If you increase the clearance beyond 15 thou. ...... rapid wear of the tappet/valve faces will occur. Best wishes. John Why? On a side valve engine these are co-axial. Barry. (...I keep thinking about this, and in practice the larger the gaps the engine does sound more 'tappety'. So there must be extra energy at the point of impact and hence more wear, but I do not really see why this should be case.) (and thinking a little more, with larger gaps the point of impact occurs at a steeper part of the cam ramp whre the acceleration is also greater, hence the bigger 'tap' and more wear. Perhaps it was too early in the morning to think straight!) Edited February 6, 2013 by Asciidv Quote Link to comment Share on other sites More sharing options...
mattinker Posted February 6, 2013 Share Posted February 6, 2013 Side valve engines have a short valve train therefore 12 thou would seem reasonable as an engine hot clearance. I doubt there is much overlap on this engine, and it won't be too sensitive to valve timing. Try it and see! Regards, Matthew Quote Link to comment Share on other sites More sharing options...
Barney Posted February 6, 2013 Share Posted February 6, 2013 (edited) Why? On a side valve engine these are co-axial. Barry. (...I keep thinking about this, and in practice the larger the gaps the engine does sound more 'tappety'. So there must be extra energy at the point of impact and hence more wear, but I do not really see why this should be case.) (and thinking a little more, with larger gaps the point of impact occurs at a steeper part of the cam ramp whre the acceleration is also greater, hence the bigger 'tap' and more wear. Perhaps it was too early in the morning to think straight!) Yes Barry your last thought is exactly right; the acceleration rate is faster which makes the hammer blow stronger. Best regards. John Edited February 6, 2013 by Barney Quote Link to comment Share on other sites More sharing options...
Jerrykins Posted February 6, 2013 Share Posted February 6, 2013 On a 'modern side valve engine' from what you learned gents are saying suggests the tappet clearance should be smallish and yet the workshop manual for the MCC 6 cyl Cs8 or 4 cyl C4 states 19 thou (inlet & exhaust) or 4 thou (inlet) and 18 thou (exhaust) respectively. I own the latter version and they don't clatter unduly and the pushrods aren't terribly long. From an operating view I'd rather they clattered a little rather than burned. I'd appreciate your views and thank you for a thoroughly interesting restoration blog. Jerry Quote Link to comment Share on other sites More sharing options...
Great War truck Posted February 6, 2013 Author Share Posted February 6, 2013 One of the things that we shall require when the engine is ready to fire up is a Starting Handle! Included with the engine which we obtained from NZ some years ago was a Starting Handle shaft – but no actual handle with it – but looking at that shaft now with its fittings, it is not like the one illustrated in the Thorny J Parts Book that we have! There is a drum about 6 or 7 inches in diameter adjacent to the dog which has a thick rubber coat on it and now thinking about that, could it be for a friction drive for an electric starter? It could be original Thornycroft – but for a later perhaps post-war “J”. We have just discovered today that the top water manifold that came with the whole engine is not in fact for a war-time “J” but appears to be designed for a low-level radiator “J” – which was post war! So do we have an engine from a later Thorny with the low level radiator? Otherwise, the engines are the same, but we are faced now with either cutting that manifold and inserting another section and welding it up – or more pattern making for a completely new part! This starting handle shaft we have had in our possession for many years but the “dog” has completely corroded away. The carrier for it which bolts up under the front stretcher is sound so that can be used again. Fortunately, the shaft in the wrong NZ one mentioned earlier but with a sound “dog” is identical in all measurements except it is just slightly longer overall, so the plan would be to get that out – it is quite corroded in and use that with the carrier from the other one. Then it would just mean making a new handle! Quote Link to comment Share on other sites More sharing options...
Great War truck Posted February 6, 2013 Author Share Posted February 6, 2013 These four pictures show the NZ shaft with the sound “dog” and the rubber ring removed. The NZ shaft is out and has been offered up to the correct carrier – everything now wants a good clean and de-rusting Quote Link to comment Share on other sites More sharing options...
mammoth Posted February 7, 2013 Share Posted February 7, 2013 (edited) I have recently aquired a J type instruction book. Valve clearance is given as 5 thou hot, no mention of any difference between inlet and exhaust. Ignition timing is "about 32 to 35" degrees before tdc fully advanced, corresponding to 6" to 61/2 " circumference of a 211/2" flywheel. There is no mention of valve timing. In relation to a much earlier subject the governor is set at 16mph. The book I have mentions electric starting, with reference to pinion engagement. However, the spare parts section does not cover electric starting. Edited February 7, 2013 by mammoth Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.