The BSA A7-A10 Forum
Bikes, Pictures, Stories & more => Other BSAs, Other Bikes, Cars, Machinery & Tools => Topic started by: RDfella on 30.12. 2022 20:12
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Thought I'd start a new thread - just in case I'm daft enough (at my age) to start a new project *eek*
Already mentioned in cylinder head? post, so here's an update:
Lot of things to consider before actually deciding to commit funds and 'go for it'. The cylinder head being the first.
After much on-line searching I cannot find, considering suitability and availability, a better option than Enfield. But, like most things to do with engineering, a compromise is required. In this case, my aim is for an engine of around 750 / 800cc - which is where the first conundrum arises: the Enfield 350 has a veteran-era bore / stroke of 70/90. I couldn't accept that - I prefer square or over-square. 78 x 78 gives near 350cc, but a bore of that size would be a mis-match with Enfield's 350 head, insomuch as the head bolts would be perilously close to the CI liner in my alloy barrel - if not colliding with it! So a 500 head (with more appropriate ports & valves) is required.
But wait - a 78mm bore is way under the 500's 84mm bore. Will that mean the combustion chamber overlaps the cylinder - or the inlet valve hits the cylinder (as is the case with BMC 'A' series engines when modified). I won't know until I can get my hands on a 500 head (hopefully soon). And will the head gasket adequately seat on the liner without stressing the flange?
Also, it looks like I'll need to make a gasket to suit, reminding me that was actually the greatest problem I had to solve with my last vee. Try as I might, I couldn't get the fire ring to compress the variety of materials I tried. I figured what was needed was a material that compressed when the fire ring was applied, but not so compressible that it would fail in service. Found a firm (major gasket manufacturer) who confirmed my analysis - but they don't supply raw materials to the public! Soon after my enquiry to that firm. I received a parcel containing supplies of that material - together with a note "you don't know where you got this from"!
So I've been trying to compromise on bore / stroke dimensions. And here piston selection come in (I refuse to make cylinder heads or conrods and seek to avoid making pistons if at all possible). So what's available piston-wise in the 78 - 80mm region? Not a lot, it seems. There's a Ford Mondeo piston @ 83mm, but that'd mean a stroke of 70mm or less. OK, my last vee is 92/75 but that was designed for racing. I now want a more moderate engine - heavier flywheels, nearer square bore / stroke etc. And so ages were spent investigating on-line.
There's a Commando piston avail by Wiseco at 80mm, but at eye-watering price. Same with KTM and others. Then I discovered a Vauxhall piston at 79mm. And at a reasonable price (considering this - if it goes ahead - will be a prototype and could well end up scrapped if major problems arise). And so that is another item 'parked' for now.
But what about conrods?
Again, much on-line searching, with little progress. If I go for 79mm bore (and complimentary stroke of 76.5mm) I will need a conrod of around 6 1/4" to clear the 7 1/2" flywheels I've figured would be a good compromise. Whether that rod has a roller or shell big-end I don't really care, but will need to know before making the crankshaft (which, because I no longer have access to heat-treatment facilities, will need to be pressed-up as opposed to one-piece).
Sadly, very little is available, mainly due to the fact car rods are quite short because they have no flywheel to avoid. The only candidate I have found so far is BSA CB/DB (the shortest of the 3 versions - ZB was the longest and BB the intermediate). A10 / A7 may be another option, but would mean another pair of new Thunder rods (am trying to keep the cost down and prefer steel anyway).
I have one CB rod, but would need another - does anyone have one they're willing to sell? *????*
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RD,
This ratbag is a member of our club.
You might be interested to check out some of his creations.
He likes offset cranks and big bore motors.
https://www.bmcmotorcycles.com/you-tube-channel-links
cheers
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A month later ... and an update (yes, I am daft enough to start another project) *eek*.
Covered all the considerations / possibilities in my opening post, so here's where I am now:
With the likelihood of access to a heat-treatment kiln (after a lot of searching) I can proceed with my preferred one-piece crank. That means split big-end rods. Bore / stroke requirements mean rod c to c length of 6" or just a touch over. My preference is steel rods, but little is available (my favourite VW rods @ 144mm are too short for this engine - car engines have their flywheel at the end, so no need for long rods to get the piston clear of the crank).
Ended up choosing Bonneville T140 rods. Alloy unfortunately, but at least better than BSA ones insomuch as they have steel caps.
Pistons? Bought a pair Kawasaki ATV pistons @ 77mm, but then discovered, because of the volume of the heads I'm using (AJS) I will need domed pistons to reach my preferred 7.5:1 CR. So have just bought a pair of 76mm T140 pistons. At least they'll fit the rods, unlike the Kwaka ones, which were 18mm. Too little material to bore the pistons to the rod's 3/4" yet not enough difference to fit a bush in the rod. At least that's solved now. *smile*
Cylinder heads? 4 valve would be a nightmare on a vee twin, so there's very little to choose from. Enfield ones would have been ideal, but bare head prices are usually above £200 - each. Ouch.
And so I went for AJS, but they need a lot of work. They have a counterbore 'register' where the cast iron cylinder locates. I need a flat surface, so that means welding that up. Also, the head bolt holes would be too close to the liner in my alloy barrel, so need moving further apart. And - we're not finished yet! - the inlet port needs shortening for the rear cylinder and moved sideways considerably for the front cylinder (else the front carb will be stuck in the rear's exhaust).
Have made a start. First pic shows the std recess and bolt holes, 2nd shows my mate Russel's welding and 3rd is after machining but before inlet is modified. Getting there slowly!
The eagle-eyed will notice the pushrod holes are different between the top and other head. That's because the top one is an earlier model - same in all regards except the pushrod arrangement. Suits me to convert the later one to the earlier design.
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G'day RD.
Your a brave man mate.
When I re-located the four outside head bolt holes I made threaded plugs, alloy for the head and CI for the barrels. Then drilled half in the plug and half in the head/barrels.
Cheers
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Hi RD
Looking forward to seeing progress on the new Vee *smile*
MAP cycle is USA make Steel conrods for Triumphs, BSA's etc
If the budget would stand it?
http://www.mapcycle.com/categories/engine-top-bottom-end/connecting-rods.html
John
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MAP cycle is USA make Steel conrods for Triumphs, BSA's etc
If the budget would stand it?
Never run to a budget on these sort of jobs - never know where things will end up! Just keep the cost down as you go along without making silly cuts that'll come back to bite you is my motto.
As to those rods - am aware they and a couple of other firms make them, and realise H beam rods have fans in the racing world, but I just don't like them - can't see the logic behind the design.
pics of crank 1, as arrived and 2, current rough-machined state before stress-relieving and then final machining. Turning took 15hrs (steel is quite tough and offset turning means cuts of no more than 1 mm at a time). Despite copious coolant chips came off blue.
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Will you explain that crankshaft to me please. By the way; lovely finish 👍
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Only roughly machined, I'm afraid. As stated, it needs now to be stress-relieved, before final machining (mainshafts reduced, threaded etc, oil ways drilled and BE ground) then it's off for nitriding. The layout will be similar to my 1,000cc model, although stroke is 80mm instead of 75mm and flywheels will be 1/2" bigger OD. Started with 25+kg of EN40B bar and after turning it's 4.5kg! Bobweights will be mild steel.
Attached pic of the 1,000cc one for reference. The threaded holes are to permit changing of balance factor in situ without dismantling the engine.
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So does that central journal have side by side big-ends or is the second conrod bushed to the first conrod, or is there a Y shaped conrod with two pistons on it, or is one big end forked around the other?
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So does that central journal have side by side big-ends or is the second conrod bushed to the first conrod, or is there a Y shaped conrod with two pistons on it, or is one big end forked around the other?
It can be seen from the width of the BE and the oil hole arrangement that it's twin rods, side by side. Actually an advantage for vee twin motorcycles, as it gives a bit more clearance for the rear exhaust and front carb.
In my view a hinged pair of rods are a compromise that should only be considered when other options are inconvenient. The 'hinged' rod will give slight variations in timing and piston position as it's not always perpendicular to the BE. Usually used in radials where multiple rods mount on one BE. I'm not a fan of forked rods either (yes, I know Merlins had them) because, in my view, the forked rod is weaker. Again, only necessary if it's important that cylinders should be inline.
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Ah yes, I hadn't studied the other picture very well.
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Again, only necessary if it's important that cylinders should be inline.
Aesthetically better if the cylinders are in line; Indians and those other American things traditionally had knife-and-fork B/Es which look better than say, those off-set Morini Vee's.
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April update: been busy making crankcase patterns. Had forgotten how long all this takes - previous ones were made in my spare time, but this engine is a more concentrated effort.
Crank has had BE ground, just waiting now on delivery of mild steel discs (200mm x 30mm) to create the bobweights. The first pair were 'lost' in the post, but expecting the replacements any day.......
Pic is of drive side crankcase pattern - about half completed. Quite a bit of time is taken up creating draft angles on every part to ensure the pattern will extract from the sand.
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Bit more today - drilling crankshaft to mount flywheels (6 Allen bolts & 2 x dowels each side). Next it's a strip down again to send the crank (minus flywheels) off for nitriding. Flywheels are mild steel and have no need to be hardened. Last pic is the amount of swarf generated from turning crank and flywheels - about 3 x barrow loads *eek*
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May 1st - well, crank has been nitrided and today I've just finished touching up the crankcase patterns ready to send them off to have a firm near Berger do the casting. Been using Butlers for over 30yrs and have to say I've never had a poor casting.
Time now to do a bit more on the heads and make a start on a cylinder barrel pattern.
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Impressive pattern making. Do you need to allow for shrinkage?
Do you have more than one set cast?
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Hi GB,
Yes, there are several considerations to be taken into account. First is draft angle (I use 2 *) otherwise the pattern will not extract from the sand. And that applies to all parts of the mould. Shrinkage allowance depends on several factors - type of alloy used, pouring temperature, effect of 'risers' placed by the casters etc.
And, as always. I have two of everything made. If I make a cock-up when machining or the engine goes bang later on, I don't then have to go through the process of getting more castings made. Making two of everything (or in the case of barrels, three) is more convenient and cheaper to have done 'whilst they're at it' than the alternative. And that way one can be sure they'll never be needed!
I'm not a pattern-maker by trade and glad I'm not. It's something that might fascinate the sort of people who spend years making fantastic model trains, but I don't really enjoy it. It's the fiddly bits, like trying to get a perfectly smooth radius (and draft angle!) at the base of the lugs you see inside the timing cover that test my patience. And these are relatively simple, one piece patterns. Imagine making a pattern for a cylinder head where several inter-locking parts are required - all able to be extracted from the sand. And that's without worrying about cores for ports etc.
As it is, I have to make a core box for the new cylinder barrels, but at least that's straightforward. Even the previous engine wasn't too bad, where the cylinder barrels needed a core for the timing chain tunnel as well.
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Bit more yesterday.
Crankcase patterns are currently winging their way to the foundry and the crank is on its way back from nitriding, so I set about one of the smaller jobs - making the cams. Last pic is of the finished product before case-hardening. I chose the 'K' profile as it was the only suitable one I had to hand. It's slightly more dwell (310 / 295) than I'd prefer, but the ability to design something better sadly went with my mate George. I used to enjoy designing cams, but without access now to a decent pantograph I can no longer get a master cam made from my pattern (from which the finished product is copied).
Really must make a start on the cylinder barrel pattern.
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G'day RD.
The black art of valve/cam timing. 310/295, 99 overlap. Just a bit more inlet than the 357 cam (299/295, 88 overlap).
Your a clever fella.
Cheers
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Castings arrived today.
Been rather busy these last couple of weeks: lathe needing bearings replaced, two of my classic cars and my daily driver developing faults (managed to get home each time without the dreaded breakdown truck). Then my two pillar lift started playing up - transpired a bad connection in the switchfuse meaning the voltages were 240/240/80. Finally my fishing launch needed a bit of TLC including a rudder restore where part of the blade had got loose - glue had given up retaining the dowels, but I did build it 47 years ago! Oh, and I'm putting a new tiled roof on a cottage washhouse......
So not much time for the bikes, but must make a start machining those cases.
As usual, quality of the castings is excellent; been using Butlers on / off for around 40yrs.
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I imagine converting those castings into beautiful engine casings is something you look forward to.
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Crikey RD, how do you find time to eat and shIt *????*
Cheers
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Crikey RD, how do you find time to eat and shIt
Sometimes I have to resort to concurrent ...
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Sept 4th - bit more progress. Been kinda distracted recently with property maintenance, eg replacing the washhouse roof on a cottage I own. A real nightmare these 400yr old buildings - nothing is plumb, square or anything else. Fitted new wall plates, rafters and battens - I'm currently about 3/4 way through replacing the tiles - even they're a PITA, as every one is a slightly different shape to the next one.
Anyway, I've managed to get a couple of hours in the workshop. Started machining the crankcases (seen here making the register) and put the tapped holes in the crank flywheels for fitment of balance plugs as required (5/8" UNF x 3/4" deep, 10 off). Essential when the most suitable balance factor is anyone's guess. *smile*
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Thank you for updating us. I'm sure most of us are following this thread. 👍
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Getting there slowly. Got around to making an engine stand this afternoon - better than chasing the engine around the bench, especially as the next job is to sort the timing gears. I'll be a bit held up though, as I'm waiting on a mate to surface grind the timing outrigger plate, and I still haven't ordered case-hardening material for the cams. Been unusually disorganised recently - too many things requiring my attention concurrently. Mind, forecast is good for tomorrow and, with one of the biggest tides of the year, I'll be out in the boat.
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Hello 👍
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July '24 - getting there slowly. Crank cases now together and building engine around it. Barrels are finished, waiting for heads (much modified) to return from blasting (quickest was to clean fin area) so I can fit the guides I made together with Ford Pinto valves.
Gearbox overhaul next. Almost a problem with the clutch - was designed for belt-drive plunger type, but opted for Norton. Trouble is it's a fair bit bigger and almost doesn't fit in the primary. Also, converting it to belt looks nigh impossible.
Most vital parts made now, so now it's assembly time - together with modifying a PAS rack and pinion to fit my Ford.
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It looks good and strong *smile*
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Bit more progress. Timing & drive side. I'm using - much modified - AJS cyl heads (moving the inlet ports, converting to coil springs, enlarging / angling pushrod tunnels, welding face that mates to barrels, widening mounting bolt pcd etc).
Now looking for where I've left those pesky magneto bolts / screws ... Gearbox is plunger, clutch Norton.
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Breathtaking mate. Incredible work.
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Yeah, from talented people like this to those who ask questions like "which way do I push the A/R lever when starting?" or the immortal "which oil shall I use?".
Motorcycling is a very broad spectrum..
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I'm totally gob smacked , never commented before but just mind boggling to someone like me who doesn't know one end of a lathe etc from the other *respect* *respect* *yeah*
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topdad i know lathes but no way capable of RD's work, maybe i spent too much time in the pub instead of dads workshop like MWAS did.
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Bluddy'ell Talking of lathes, I spent yesderday afternoon trying to get my old Seneca Falls to run better. Trying to get all the alignments and tensions right so the belts stay on the pulleys. If anyone thinks old 'bikes are difficult... try an old lathe ! *work*
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Getting things as far forward as possiblr before my op on Monday ...
Engine well on the way, and frame now finished. Had to lower the frame 1/2" to get filter out and cut out two BSA engine mtg lugs. Added a pair of lugs up front and two underneath to locate the new engine. Also cut off the old tired stand lugs and welded two new ones on. This morning (sun shining!) I gave her a sound coat of two pack. Hope it dries before rain ..... Apparently a shower is 20% possible.
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Dear RDfella,
I just cannot wait for an update and find that there is none. I need to ask and hope, it is OK for you: how is the project "another vee" going? I wonder, how the framework is doing and which set of carbs found your choice eventually. What kind of tank will you use and so on, etc. etc.
Thank you in advance for another chapter report.
Best regards
Manfred
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Guess progress is relative.
Engine well on the way and in frame. Gearbox, front forks (Suzuki GS750) & wheels on (I like discs up front).
Oil tank repaired (new inside tube) and the fuel tank clears the motor fine - just needed (done today) the RH fuel tap moved forward about an inch and a half. HOORAY - wasn't looking forward to making a new bottom for that.
Held up now waiting for a few small bits & pieces in the post, like some 2mm alloy plate (I only keep 1/16" and 6mm) to make a spacer for the mag behind the timing cover, 'cause I don't want to recess the latter. Halfway through making the exhaust system. I'm using SS tube with mandrel bends cut to appropriate lengths and tacked together. I have MIG and TIG, but am hopeless on thin walled tube, so after tacking it goes to my mate Russel who's the DB on alloy welding and thin SS tubing.
Have opted for Monoblocs (had one 1.1/8" already) but need the odd part to complete. They're 389's - would have preferred the smaller 375's but the latter are like the proverbial rocking horse droppings.
Just found - this afternoon - that the new alloy rear rim, although central to the Ariel hub, is offset in the frame around 1/4" so have moved it over.
Still loads to do, such as make a roller plunger for the gearbox and a working oil feed to the valves instead of the bit of wishful thinking AJS came up with (I'm using AJS heads as there ain't much else suitable and I can't contemplate making a cylinder head pattern).
Enough for now, will post some pics soonish. In the meantime, hope everyone has a healthy and happy festive break. Don't forget Christmas day is actually the start of the new year (previously a pagan festival commandeered by the Church) so the days will start getting longer from next Wednesday. *smile*
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G'day RD.
Great to hear of the progress mate. Yes please to the pics.
Was the longest day of the year down here yesterday. Another month till it gets real hot.
Cheers
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Well, here's a couple of pics.
Been busy on other jobs, so progress a little delayed. I'd forgotten how much there is to do.
Engine bolted in now and next jobs are: to complete the return feed to rockers, which I've also spliced off to feed the inlet valves (standard on AJS). Also fuel tank to complete, were I've had to make an insert to clear the front carb. Front mudguard to make brackets for and the top yoke / headlamp brackets to refit. Cables for throttles, clutch, decompressor and retard to make up and oil gauge to mount then put bike on rollers to check oil feeds OK. Seems never ending.
Well pi**ed off with whoever designed those oil tanks. Must have been on the hooch. Spacers, special bolts, brackets and washers - and still it's hard up against the frame (the return pipe was nearly worn through). What'd have been wrong with three stud fixing, with grommets if they were concerned about vibration / insulation issues?
Anyway, onwards and upwards.
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RD fella you will get there because your an engineer , when i was building the berger thing as a non engineer and had to make things work together i went to bed thinking only that and that and that to do but but it wasn't as easy as that in practice using just a frame and an engine that had never mated from the factory, i have said i will never again get a bare frame and build something that has never been together before. i had nearly finished it when i realised my home made brake pedal was not going to work and had to get it altered just like other things that once in place upset something else. then along came a notrun man telling me i had the seat in the wrong position , maybe for him and how they built tritons years ago but i built it to suit me not him. *beer*