As a last post on the subject of correcting the valve timing on the Leak Compound in Befur (prior to “sea trials” later in the year), here we will look at the results from the static (blowing) valve timing tests, and compare to the results prior to rebuild. But first a video of it running on air with the new timing…
I just updated this post to improve the pictures and ordering to allow simpler comparisons between old and new timing data.
This time we are looking at how to fix the problems with the Leak’s valve gear design. This is now part of our Leak Hints and Tips section on the known errors or problems with Leak design……
As we get to the end of January 2022, the tuning/rebuild/shopping of Befur’s engine continues, once this is complete we can get on with the list of hull and fittings-related work. But it seems we should at least explain what work the last few months have contained…
HP valve Bobbin ready for measurment
The next stage in the refurbishment and sorting of the valve timing issues is to pay some attention to the HP Valve problems.
The Digital Engine Indicator
As my first job was working as an Instrument Technician for Shell Research in the Applied Physics department, I became interested in the measurement of physical systems… thus I was interested in Engine Indicators as a tool for evaluating engine performance, and measuring valve events and gas-flow in steam and very large marine diesels.
An Engine Indicator – Wikipedia Commons Image
Given my later life in computing I concluded that a digital version of one of these instruments could be made to evaluate the performance of Befur’s engine.
I penned an article for The SBA’s Funnel magazine, but the publication of this has been delayed, so I am publishing it here for those interested.
It’s still a prototype, and in need of further development, but it has provided some interesting data – which at least prompted further analysis and investigations into what happens inside Befur’e engine…
As you may have seen from earlier posts, and here we are embarking on a major winter “shopping” of Befur, to address a number of problems.
Measuring the valve timing on the bench
One of these tasks is to analyse and reset the valve timing of the engine to improve efficiency and performance. Continue reading
Befur home for winter work
Well, Befur is back in the fells for some winter work.
The pull-out and trip home was uneventful, thanks to Simon and Dean’s help, and the garage finally finding and fixing the leak in the Land Rover’s turbo pipes! Much less smoke and much more go!
We have a tentative list of work we want to do, and the game plan is to try to get back into the water before Heggerscale freezes (the lake is a milder climate to over winter in)! However, as I write this post, and document the work, it seems questionable if we will finish the work in 2022!!!
The work falls into several groups, some just inspection/maintenance and some fixing/improving: Continue reading
Just a note to record the things we have been doing over the last month or so.
Most importantly we have secured a berth at Ferry Nab on Winderemere, so Befur will be exploring new waters this year. So, as always, the cosh is upon us, with the berth being available from the 1st April (yes, we know, not an auspicious date!).
The work has divided into annual maintenance, finishing/installing the sailing rig and finishing the fit-out of the galley – and sundry diversions. Continue reading
For about a year now I have been saying “Yes, the engine is done, apart from a few bits and bobs” – so the other week I found myself waiting for some timber to arrive and decided to just “knock those bits and bobs on the head” – 10 minutes inspecting the engine revealed that there were in fact (at least) 23 jobs still to be done!!! So so far we have spent two weeks reducing this list to 7…. (and deciding to do some much later!) Herewith some notes on some of this activity… Continue reading
Well as the videos below demonstrate we have the valve gear finished, and I managed to time it reasonably. There is some blowby on the HP, and that might need further investigation, but on the whole it’s OK.
I scratched my head a lot on how to set this gear, and while this might not be the “right way” and the setting is certainly not “perfect” – let me tell you how I did this….
Firstly we set the engine up so I could feed each cylinder from compressed air, with “ball-a-fix” valves to allow me to control the amount of flow, and which cylinder is fed. Also fitted a small pressure regulator to allow me to control the pressure fed to the engine.
This set up allowed me to turn the engine over by hand and feel when the air pressure was assisting or hindering this turning, and thereby determine if the gear was feeding the pressure at the right part of the stroke. Then one could simply say “is the gear ahead of the crank position?” (e.g. the air is being fed too soon, or cut off too soon), OR “is the gear behind the crank” (e.g. the air is being fed too late). It was then quite simple to slack off the allen screw locking the eccentric to the crank, use the key to hold the eccentric in place, and manually move the crank ahead or behind (forwards or backwards) to attempt to correct the error. I did this first in full-forward gear and then repeated the same process for the HP cylinder, and then in full reverse (setting the relevant eccentrics).
Three or four iterations produced the results shown below…
Firstly running in (very) slow forwards
Secondly, a “video tour” providing a more detailed view of the various components?
Well, if you’re building this engine then I hope the valve gear goes more smoothly for you than me!
A handfull of work, drag link bearing blanks ready for drilling boring, fitting and oil-hole drilling
I cannot believe just how long it has taken to complete the reversing gear on the engine – and it’s still not done.
The multitude of little blocks (drag-link bearings) take an age to make – if you had some 7/16″ sq Ph Bronze bar to hand then it might be OK, but I didn’t so decided to hack the blanks out of a piece of 2-inch square bar I had. However, I discovered that my trusty Warco bandsaw did not cut as straight as I hoped, and half of the resulting blocks were undersize. So then you spend a while silver soldering extra bits back on, to bring them to size, and then (literally) DAYS on the shaper, transforming a set of rough cut rhomboids into little cuboid shapes.
Meanwhile a relatively simple turning and pressing job produces the pins for the lifting arms and eccentric pivots.
Drag Link bearing pins pressed into lifting arms and allen-screwed into expansion links.
I happened to have some EN1A on the shelf that these got cut from – this is lovely free-cutting (leaded) mild steel, but I must confess I worry that this is so “soft” that it might not last well in service.
BTW – Midway thru the gear building I ran short of 1/4MS bar. So I went off to Metal Super Markets in Southampton (metalsupermarkets.com) and stocked up on a variety of bar and plate, that my “stores” were running short of; (these really are great people, and very helpful and economic – I would recommend them to anyone, over the counter service with a smile, for even small quantities) – But they only had EN3B, and when it came to turning and screw-cutting this stuff you really miss the free-cutting EN1A!!!
The only issue with the manufacture of these pins, is that one of the errors in the drawings means these pins need to be longer than drawn, to clear the bolts and lock nuts securing the Expansion Links and Die Blocks. There’s not a lot of space, so take care – I extended mine to 1.5″ overall (I think).
The next job was to drill the bearing halves for the rods. I did this by clamping them into a small jig (with tool-makers clamps). My normal approach to this would be to soft solder (“sweat”) the bearing halves together and then drill and bore them as one, separating them at the end. But this was not what the ME articles said – so I followed them… The plan was to create a small jig, drill half the blocks 2BA clearance and the other half 2BA tapping – then tap these and use temporary screws to assemble them into pairs while they are bored, and then open out both sides to clearance for the long rods to be fitted.
Jig Drilling DragLink Bearings
I think this approach was slower. A better plan would have been to solder them into pairs while they were all still oversize, drill, bore, finish to size and then separate.
As it was I then discovered that despite machining all the blocks to size, the journals on the pins were too tight (only a few thou, but enough to stop them fitting, so yet more fettling was needed)- At this point I discovered that the relevant reamer has gone missing, so more careful hand work on pins and bores (scrapers and emery tape) was needed to get a good fit….
The Valve Rods
This is about to start sounding like the blog of a complete idiot, but at least it’s improving my patience.
Firstly, while assembling and testing the valve gear (prior to first run on air) I found that the LP valve was fouling something and could not accommodate the full travel of the eccentrics, over a couple of hours of assembly, disassembly, reassembly (repeat as needed) I came to the conclusion that the tailrod was too long and clouting the end of the tailrod guide… there being no opportunity to lengthen the guide, I decided to shorten the tail rod – carefully sawed 1/4″ off, and reassembled again, only to find it STILL DOES NOT FIT!!!!!
Further inspection determined that the valve buckle was actually fouling the nut holding the tail-rod guide – and actually the shortened tail-rod was now falling out of the guide at the lower extent of the valve travel!!! So, it now needs lengthening – more work yet to be completed…
The HP valve rod has a “joggle” on the bottom to line up the valve rod with the eccentrics. I decided to make this as a separate part and screw it to the rod proper. This joggle also serves to further widen the already widened drag-link pins resulting from the error in the drawings. I did measure this and allow for it in the longer pins – but I forgot to take account of the lock-nut on the die-block pin….AAAARRRGGG!!!
I concluded I could shave enough off the joggle to accommodate all this, but the amount of metal left for the thread holding the actual valve-rod into the joggle was going to be a bit thin, so I decided to braze the rod into the joggle – this I did (with no distortion), and decided to use the Linisher (belt sander) to just clean the flux and oxide off the joggle…. What I failed to see as I did the final side was that I was holding the assembly slightly out of square and ground a nice 20thou depression in the bally valve rod – thus rendering the whole shooting match scrap! 😐
Either way it provided me the opportunity to screw-cut the 3″ long 3/8″x26 thread on the new rod, using the off-set compound slide method often recommended (but never tried by me) mechanism – and it does a much nicer job (even on the nasty EN3B!), so I conosoled myself that the extra 3 hours work, had resulted in a nicer job (displays a fixed grin)!
BTW, In this process I again reminded myself that under conditions where you need to take fine cuts on tough material a carefully sharpened carbide or carbon steel tool will outperform a indexable tipped tool – as if you check the specs these are not typically made to make a cut of less than 5thou !
Jig Boring the holes in the lifting arms for the weighshaft and drag-link pins
Overall these 16 half bearings and eight rods and 4 pins took more than a 10 days of effort (probably about 30 hours! not including the remaking of the vale rod) – a slog…. assembling the whole sh-bang produced something that worked but was too stiff, so more fettling and adjusting needed!
I am really hoping I can bring this all to a good end – sometimes I wonder!
SY Befur 