JAPton blog

[Rockburner]

Gulp.... here we go....

Time to start the assembly!

First I checked the locating of the crank oil feed quill, which, for some reason, my Dad had left out of the engine when it was last buil! How the big end was getting oil I have no idea.....
I only ordered this recently, I had no idea it was supposed to be there until I spotted it on the Speedway Service list of parts and wondered what it was.... If I hadn't lost the little seal from the timing cover and had to order new ones I'd never have known about this part.



I also checked the crank-shaft oil feed line was clear:


Yup!


I then set up the timing side crankcase on a few blocks so that it would sit easily, cleaned up the remaining lithium grease which was on the thrust washers on the crank shafts, fitted the bearing cage and rollers on that side, and dropped it into the case:


Fitting the bearings was a lot of "fun" - they're soaked in R30 and have a tendency to try to pop out when you're pushing the next one into the slot: this little so-and-so made a bid for freedom and I lost 10 minutes hunting for the git, eventually I DID find it on the floor, I think it somehow ended up under my shoe!


Second set of bearings all in:



I then cleaned up the case mating surfaces with Sika Wonder Wipes,



Then again with meths on a clean bit of cloth.

Just a fraction of the blue paper and wipes I went through....


The Threebond was a lot more fluid than I was expecting, and I lost a bit of time hunting for a nozzle amongst my other tubes of goo - unfortunately couldn't find anything to fit so I had to just dispense from the tube.
I think this was a little too much - but there wasn't a "huge" amount of overflow on the outside of the cases.



Note that on this side of the cases (the Timing side), there's a "wall" or "lip" on the inside of the mating faces - this provides a locating key for the other side and a partial "labyrinth" seal, it also means that hopefully there's a lot less chance of the Threebond getting into the inside of the cases if you apply it to this side of the cases (as opposed to the other half), well - that's my hypothesis anyway...

I fitted the other side of the cases, used the small bolts to hold it together and align them, then fitted the workshop legs and cleaned up the small amount of excess 3Bond that oozed out. (the Wonder Wipes were very good for that).

The next step was to fit the output side crank seal - this is a modification to the original engine, I'm guessing from F500 racing, and I really ought to try to find another one at some point.
I 3Bonded one side of the gasket (the cases side) and fitted the ally seal mount.
Interestingly, the 3 holes are NOT in exactly 1/3rd circumference locations, the screws wouldn't screw down until I rotated the mount 1/3rd. If I remember I may etch an "up" arrow into the ally just to make it easier next time.


Test-fitting of the timing wheel - as I was looking at the cases on the legs, and the wheel hanging on the wall I had a sudden panic that it wouldn't fit!!
But it does.


It's a nice tight fit on the output shaft splines. I also like implementation of the fine-adjustment collar.


Woodruff key, splines, output cog and fixing nut, There's also a couple of large washers that fit over the nut which stop the cog sliding off.



I rummaged around in the box-o-bits but couldn't find another nut of the right size and thread to temporarily hold the splines on the shaft: this nut is the right size, but wrong thread, but it'll do for now just to stop the splines falling off.


I need to make up a pointer for the timing wheel: current thinking is to just use a bit of wire-coat-hanger and one of the mounting studs to hold it in place, can't see any problems with doing that, so will do that when I get to that point.

Next job will be the barrel studs (copa-slipped, and with a touch of grease on the rotating bits), barrel, with 3Bonded paper base gasket, quench the head gasket : Ooo - a heaty bit, watch out for fireworks!, and the head, rocker box, then timing gear..... should be fun!

[Skub]

All the future Japton builders will be referencing ye olde RB scrolls. Get it all into print and live happily off the earnings.

[Rockburner]

Next stage.... the barrel.

These are the barrel studs. The little discs above them go into the blind holes in the cases first to act as a "bump-stop" and (I think) to help against galvanic corrosion (or something)


Each one gets a small amount of copa-slip (One day that tub will run out, and I will be left hopelessly bereft!)


All in situ, and tightened down hard:


Cleaning up the excess copa-slip that was left


Ready for the piston: already have new rings and gudgeon pins.


The first bit is easy - piston and pin slid together nicely.


The circlips though were a bit of a fight to get in - but eventually I worked them in with a large pair of needle pliers (which is probably where that scratch on the piston came from. hey ho.


The second one was just as hard to get in.



Imprompto hook (from an old bungee net) bent up to keep the piston from flailing around.


Sika Wonder Wipes and meths again to get the base gasket surface clean


3Bond application, tried to put the minimum on this time, so just dabbed it on lightly and spread it out thin








The base gasket was fitted and more 3Bond lightly applied to the top surface of the gasket, then I checked the ring gaps: they just need to be "opposite" each other, and from memory, they shouldn't be directly on the "thrust" sides of the piston (ie, fore/aft), so I made sure they were lined up on each side of the piston:




Rather nice little ring-clamp from Dad's collection :


Much easier and lighter than some I've seen


And this is where I envy Zaphod Beeblebrox..... a 3rd hand would be helpful at this juncture.


GAH! First attempt and the friggin bottom ring managed to slip out after the ring-clamp had slid away!


But, after a couple more attempts (it was a bit of a fight to get the rings into the bore!)
Yay!


Up


And down she goes!


The piston moves nice and freely in the bore, must remember to drip a little oil in there just to help it slide before I do the head gasket.
I pushed the barrel down and wiped up the worst of the 3Bond excess


Then stuck the head on so I could pull the barrel down tight and let the 3Bond go off properly in compression.
Here's the head sitting on the top of the studs so you can kinda see how the studs work.
The upper part of the stud assembly is free to rotate so it pulls the head down onto the barrel. With studs like this, you can remove the entire barrel and rockerbox assembly without having to split it all up (should you want to)



However: doing up the studs is a long process because you can only rotate the stud with a spanner about 1/3 of a turn each iteration..... so I broke out my new secret weapons....


Wera Joker spanners: they're good.


You can flick the spanner back and forth like a ratchet spanner: Took a few tries before I really got the hang of it, they do tend to drop away unless you use your other hand just to keep them aligned on the nut correctly, but by f~ck do they speed up something like this! The studs go into the head by about an inch (approximately) on a relatively fine thread, so it's a LOT of 1/3 turns to do - the Joker cut the time down I'd estimate by at a half, if not more. I was pressed for time while I was doing this last bit as well, so I was very grateful for having the Jokers! (I can't seem to put an Amazon url into here - so just search for "Wera Joker Self-Setting Spanner" I have a set of 4, each one covers a smallish range of sizes.)


I left the head tightened down so the 3Bond has time to go off and the base gasket should be all set by the next time I get into the workshop.



Coming up!

Fire! Heat! Water! Imminent probability RB burns himself!

[kendo57]

A couple of parallels slid under the piston holds it steady and makes getting the barrel on easier. I watched a guy
on Youtube building Gardner engines and when he used gasket seal he tightened the cases down to a low torque
and let the sealer harden then re torqued them to the correct setting. He reckoned it produced a better seal.
Never done that myself but thought it was an interesting idea.
Looking forward to seeing your engine running , thanks for posting.

[Rockburner]

A couple of parallels slid under the piston holds it steady and makes getting the barrel on easier. I watched a guy
on Youtube building Gardner engines and when he used gasket seal he tightened the cases down to a low torque
and let the sealer harden then re torqued them to the correct setting. He reckoned it produced a better seal.
Never done that myself but thought it was an interesting idea.
Looking forward to seeing your engine running , thanks for posting.

I could have used a couple of bits of wood, and probably should have done - but I had the wet 3Bond lurking on the top of the cases and had to be careful not to get it everywhere!

Yeah - I think the idea is that the gasket sets with a touch of thickness, and becomes akin to a solid rubber "seal", that can then be compressed further? I may need to think about that on the rest of the use-cases, but fwiw everything will get another good wang with a spanner.

[Rockburner]

I think things are going well... (and a lot faster now the weather is warming up!)

So - last night I got another couple of hours in the shed and....

Dribbled a bit of oil into the cylinder to help the initial ring seal and checking of compression


I got the engine spinning a bit by hand and then wiped most of the excess that had gathered at the top of the barrel.

Then it was time for some heat!


The last time I tried quenching copper it was some brake-line crush seals and I massively over-did it and turned them into slag....
So this time I played the heat over the gasket until I had a glow chasing the heat around the ring, then chucked it straight into the water


I only did one side, mainly because I really did NOT want to over-heat the thing and warp it out of shape, so, we'll see how it goes. If it starts blowing very quickly... at least I now know how to get at it.

Shiny side up!


Buttoned up again.


I did try rotating the engine with my thumb stuck over the plug hole..... and there's definitely compression there! Whether there's enough compression only time will tell....

So - time to assemble the rocker box:
All the bits:


First I cleaned up the threads for the rocker adjusters:


Stuck the cap-heads on the valve stems : (This is exactly the sort of thing I would forget if I hadn't put ALL the parts into little trays of associated parts, as seen above, I would highly recommend this practise if you're doing a job like this).


The exhaust rocker had a little bit of corrosion on it's shaft, (phnarr), so I gave the shaft a little polish (ooer!). The inlet seemed fine.




Assembly of the rocker shaft with all their annoying little roller pins in situ:


I dribbled a little bit of oil into the roller-pin bearing assemblies to get them started, they definitely felt dry when I was first checking their movement.

As described earlier in the thread: the Rocker box assembly is done by pushing the bearing liner for the outboard (push-rod-side) as far out as it will go, fitting the top-cover of the box, then donig up tight ONLY the inboard screws, so the inboard bearling line is locked in place, and the outboard liner is "just" moveable ... then screwing the outer cover on, and the bosses on the inside of the outer cover then push the rocker arm into the box: pushing the outboard liner into the box just enough. This means the rocker arm "end-play" is automatically controlled and is hopefully minimised. I may actually re-do this process with a lot more photos next time I'm in the shed just to make sure I've done it right....

First thing to go on is the lower halves of the valve-covers.


I had to spend a bit of time trying to figure out where the washers on the bolts that hold the rocker box to the head (only 2 of em!) were supposed to go. I didn't make an exact note of this when I disassembled the bike (d'oh!) but I think I worked it out eventually. The complication is that there's also a bracket fitted above the rocker box that attaches to a head-steady which bolts to the bike's frame at the headstock, so I was trying to figure out if there should be a washer under the bracket, or 2 above.... I'm pretty sure there's no washer under the rocker box, it mates directly to the top of the head.

And that is where I ran out of time for the evening.

I'm currently pondering the idea of trying to seal the valve gear with the 3Bond - it's not designed to be sealed (it's a shale-track engine, weeping oil all over the place is a design feature), so it's a problematic process at best. Especially since I may well be placing and removing things repeatedly....

Food for thought over the weekend anyway.

NEXT TIME: Rocker box fitting and TIMING! (well, hopefully!)

[Rockburner]

Soooo, I hopped and skipped into the workshop on Friday afternoon, full of the joys of spring!

First thing I did was remove the larger half of the head-steady so the bracket that goes onto the head would be easier to fit...
My Dad's choices here are clear... this nut is NOt coming undone!


Then I undid the Rocker box again so I could document the assembly process properly (as promised).
First: Assemble the rocker arms and bearings into the bottom half of the box like so: Note the "outboard" bearing liners have been pushed "down" out of the box body, so the rocker arms have next to no end-float:


Gently put the top on.


This is what the push-rod side of the box should look like - the rocker-arm bearing liners will be proud of the box face:




Fit and tighten down the "inboard" fixing screws, This will lock the "inboard" rocker-arm-bearing-liners in place, but allow the "outboard" bearing liners to still move: when the cover is fitted on, it won't meet the box edge, because the stubs on the inside face of the cover are meeting the outer end of the rocker arms:


You can see the gap all around where the cover meets the box.


Tighten up the cover. This pushes the rocker arm against the bearing liner, and pushes the bearing liner into the rocker box.


Most of these engines have a single-sided wing-nut/bolt for the rocker cover, but I just have a plain set-screw (bolt)


The bearing liners have now been pushed into the box, and the end-float of the rocker arms is limited by the stubs on the inside of rocker cover face.


Note - this bearing liner (exhaust side) is still a little proud.


Now fit and tighten the "outboard" fixing screws to lock the outboard bearing liners into position.


The assembled rocker box: the rocker arms should "flop" about freely, but without rattling around. With that in mind, it's worth remembering that they only need a small-ish amount of movement in actual usage.


Fitting the Rocker box to the Head:
The lower valve covers go on first, then the Rocker box:


The Washers on top of the Rocker box are spacers to allow the head-steady bracket to fit easily.


Head steady bracket:


Rocker box fitting bolts - getting these aligned is a bit of a git:


Test fitting the upper half of the valve covers:


Ah - yeah... the oil feed banjo fitting - that would have been easier to fit EARLIER....
I may need to find another one of these, it's brass, and the hex "head" is knackered.


And as for these little gits....


These are the oil feed into the valve-guides, and they are a pain in the arse to fit, so I took the Rocker box off again to fit them!


They're just a push fit into small holes in the head, so sealing them wo'nt happen.

At this point I was pondering something and happened to be rolling the crank back and forth....

when I heard and felt a distinct "clunk" coming from the movement of the crank.

[Rockburner]

So... I started stripping everything down again! GAH!

A rather unpleasant discovery when I took the barrel off was this oil weep under the base gasket:




To be honest, I'd had a nasty suspicion that I'd seen dirty oil at the bottom edge of the barrel, looks like I was right. I think the 3Bond had soaked into the gasket, or maybe it just wasn't thick enough?? Don't know: but when I fit the new base gasket (I'm going to make another one because this one is very tight around the barrel base), I think I'll use Blue Hylomar instead of 3Bond, maybe, don't know, we'll see. I'm not impressed because this was weeping with zero provocation whatsoever, there's not even any crankcase pressure at the moment - the timing side is still completely open so this was weeping simply through capillary action. It is interesting though that the weep lined up with edge of the barrel base that is broken (see earlier photos). I think pulling the gasket away from the barrel base may help, hopefully!

This time I took the barrel studs off before the piston - makes it easier to get to the gudgeon pin circlips.


Another shitty video...


(Apoloies about the portrait videos, I set things up in a hurry, will do better next time!)


So - the cases were split again!



I did figure it out though...
THIS:


is scraping on THAT:


I think the big-end-shaft nut is hitting the main bearing liner locating screw:


really not sure how the design would even allow for that.. but, it appears to be what's happening. I can only assume that previously, the thrust washer on this side was thick enough to create a clearance: IIRC the two thrust washers fitted were a 0.040 and a 0.050: because I've fitted a new liner on the output side the clearance in the cases is (I think) now a tad smaller, so when I did the crank end-float I ended up with slightly thinner overall thrust washers fitted.

I played around with the thrust washers: simply moving the fitted ones around (ie, moving one from the output side to the timing side), and this did seem to create enough clearance:



But, I think I'm going to do some more checks before I start the assembly process again: I'm going to make sure that screw is down as far as it will go, and I will likely do a touch of grinding to take some metal off the top of the screw head, just to increase the clearance a bit more.
Then, I'll fit a thicker thrust washer on that side, and re-do the end-play by fitting the correct thickness thrust washers on the output side.


Funnily enough... the output side of the bid-end shaft has the nut and shaft ground away slightly in a fashion that would indicate that this issue has happened on the other side. While pondering this over the weekend (I've thought of nothing else), I did wonder if maybe the fly-wheels got swapped over when we replaced the big end bearings, but I'd be very surprised if this was the case, the crank wasn't completely disassembled: the output and timing shafts were not removed from the wheels, (and it's not a reversable assembly), so I am slightly confused.


Output side crankcase cleaned up nicely:


This stuff rocks!



So - all this weekend I've been pondering my options.

I think I'll start, as mentioned, by trying to take some material off that locating screw (won't be much, just enough to make it less of a prominence),
cleaning up the rest of the sealant from the cases,
Re-doing the crank end play with a thicker thrust washer on the timing side to ensure clearance,
Make a new base gasket (maybe with a thicker bit of paper... not sure really)
Then restart assembly.

few steps forwards.... several steps backwards.... hey ho... it's all a learning experience!

[Skub]

Nary a straight road man.

A wee dab of engineering blue might have helped to find where it was touching. Failing that,a good old Sharpie.

[Rockburner]

Nary a straight road man.

A wee dab of engineering blue might have helped to find where it was touching. Failing that,a good old Sharpie.

Yeah - I've got some paint pens which I'll probably have a go with (after cleaning everything up).

[crust]

Your 3Bond does seem very runny, mine is like toothpaste.

I wonder if its separated out in storage, mine has separated into a clear oil and goo. I work the material up and down the tube to remix it.

Fascinating thread

[Rockburner]

Your 3Bond does seem very runny, mine is like toothpaste.

I wonder if its separated out in storage, mine has separated into a clear oil and goo. I work the material up and down the tube to remix it.

Fascinating thread

I did think it was very runny. I'll mix it up like you describe and try it again.

[Rockburner]

Didn't really feel like going into the workshop last night, but nevertheless I did.

Firstly I cleaned off the timing side case:


To check exactly what is hitting what I improvised some "engineers red"

(It's a red paint pen )

Gently fitted the crank and rotated it slowly a few times (only a few)


As I thought.....




I think the crank-pin nut is also slightly scrapping the slightly proud area of the casing, the ring around the bearing liner. Hmmmm. But it's definitely hitting that screw head.
For Reference: that test was done with a 0.023 and a 0.010 thrust washer fitted (which is how it was setup when I discovered the issue).

I found a nut for helping to hold the screw in place in the vice:



Then gently and slowly took some material off the head of the screw with a file:


The (nearly) end results:


Fitted back into place:


That should be an "improvement", but I think the clearance is still going to be somewhat tight....


I then took it out again and cleaned up the slot a tad: (not very well unfortunately, but it's still functional)


I then played with thrust washers for a bit, trying to get the clearance: even with a 0.050 thickness thrust washer there was a slight scraping still happening, so I added the 0.010, and it's clearing now. This was done with the timing side case lying on the blocks, so the full weight of the crank was pushing down on the thrust washers/bearings. In practise, that won't happen, because the engine isn't mounted lying on it's side! (IE, it's the "worst case scenario" for this clearance: heat not included....)

I'm aware that when the engine gets hot this clearance may reduce, but I'm hoping that by setting the clearance as large as I can, that danger will be mitigated at least somewhat.

I'm still trying to figure out why this has become an issue when I can only assume it wasn't a problem before. I've had a look back at the photos from when the crank was rebuilt, and the ONLY nut that was removed during that process was the output side crank pin nut, nothing else was touched: so - this problem nut is the original one, and it's in exactly the same state/position as it was before.... so I'm no more enlightened as to why this nut is striking the cases as I was before. Hmmmmm.

Anyway: I fitted the 0.060 thrust washers on the timing side, and a 0.023 on the output side..... and checked the end float:
Base:

Float:


That's not bad!! There IS float with the thick timing side thrust washers, and I have a 0.020 washer that will bump the float up to between 0.012 and 0.015, so looking good so far.

I need to fit that 0.020 washer, check the float again, and check the piston is at least vaguely central in the crankcase mouth and the piston is central in the barrel, but dinner was calling me....

Bloody thing!

[Rockburner]

I guess I should also state that I don't want to be grinding material off the crank itself; I could grind down that nut and the crank-pin shaft end to get more clearance; because I don't want to mess with the crank's balance: I've no idea how well balanced it is.... but I don't want to mess with it!

[Rockburner]

In regards to the issue of the crank-pin nut contacting the bearing liner screw......




I've had a word with the JAP Guru... and his advice was to simply take an angle-grinder to the crank-nut and make clearance!

Apparantly it's a common thing, the cases are "not" exactly precision made, and there's a lot that were cast by jobbing engineering firms after JAP stopped production, so exact fitting is not always going to happen. His advice was to figure out the desired shims on the crank (to get the piston and con-rod as central as possible), then see if the nut is striking the liner screw (and the casing), and then get the grinder out!

He also suggested that if I wanted to confirm the clearance I've created, I can fit slightly narrower shims (eg ten-thou thinner), and see if there's contact. If not, then I should be good for the lifetime of the engine. Sounds like a plan to me.

He also pointed out; when I mentioned my concern about affecting the overall balance of the crank; that shaving a 1/16th off 1/3rd of the crank nut would be akin to taking a piss before a weigh-in... totally irrelevant! Which was reassuring.

So - that'll be the next thing on the list! GRINDING!

[Rockburner]

So, last night I started out by making up the new base gasket :


I have made myself a set of templates out of some thicker carboard and used that. I've trimmed the inner circle to be slightly larger, so hopefully there won't be a capillary path from the cylinder base straight out under the gasket this time.

I also made up a quick Mag-pinion cover gasket from the excess paper to avoid wasting it.


I then tidied all that away and got down to the main job of the evening. I finished stripping down the crankcases again and experimented a bit with the shims just to confirm the crank-touching-the-cases issue.

I'm sure I took more photos over the course of the evening, but it looks like the phone camera didn't actually save them, which is odd....

Anyway: here's a few shots of the same modification that was done to the Output side of the assembly at some time before:



This is, essentially, what I need to emulate on the other side.
Interestingly.... the output side is the nut that was removed when we replaced the big-end bearings: in this photo you can see that the nut has been done up slightly tighter this time than it had been before: you can just see the threads on the crank-pin becuase the nut has been rotated on the pin about 5 degrees more this time.


I decided that the grinding would have to be done.
So I cleaned up the wheels as best I could, wrapped a tea-towel around the bigend to prevent too much grit getting to it:


Protected the timing-shaft oilway:


Experimenting with the best way to clamp up the wheels so they don't wander about.


Then remembered I have a little B&Q trestle that would make life a bit easier, clamped it to that and did some taping to protect other gaps and holes:


I also marked up the approximate area that needed work:


In addition I wrapped some duct tape around the shaft just in case the grinder got away from me!

Work in progress:






I did the majority of the grinding outside (to avoid any conflagrations...!) with a 115mm Ryobi, and it worked very well - nice and controllable. The light was just enough that I could see what I was doing, but more would have been preferable.




And for some reason, that's where I stopped taking photos. (soz!)

I got to a point where all the marker had been eradicated, then, as the light was fading, I took the trestle back into the workshop and get the Dremel out to tidy up and polish. I used the Dremel grinding wheel to make the ground-away area slightly concave and to take off the rough edges, then wire-brushed and polished it a bit.

I then cleaned it all up, using meths and paper to try to get rid of as much grit as possible, before removing all the protective stuff and unclamping the wheels.

I tried the wheel in the cases with a 0.023 shim (which is the minimal it would need I think.. I stil need to figure out exactly the best shims to use - more on that later*.

The fucker is still scraping. GAH!

So - I need to take a bit more off - I suspect I just need to "round-off" the ground area so that it clears the head of the bearing-line-fixing-screw.

It's sooooo close!!


* Something from the conversation I had with the Guru: Although the recommended end-float in the Greenway book (which is the Speedway "Bible") is 0.012" - 0.015" : The Guru recommends letting it be a little looser : 0.015"-0.020"... and the engine will rev more freely. Given that my engine is "square" (bore = stroke) and will be wanting to rev more easily due to that: I am taking that advice and giving it strong consideration. The flip-side is that the Guru tends to be building up engines for actual racing... ie, they'll get stripped down again after a season, and a season is not really that many miles. So: my thinking is to compromise on this and aim for an end float that takes into account the hopefully longer mileage that the engine will do before it's next strip down: I'm going to aim for around 0.015", or slightly higher, end float: ie the looser end of the Greenway figures, and the tighter end of the Guru's advice. The aim is to have the engine in good fettle for a few years of riding around on the road with the occasional classic "parade" track-day. It's unlikely to get utterly thrashed, but I would rather not be rebuilding it every winter!

[cvilla]

Really good work, both engineering and blogging;)
No way I could put it back together, even with a full manual, 125cc new barrel and piston is my limit so far:)
Keep going we like this.

[Rockburner]

Really good work, both engineering and blogging;)
No way I could put it back together, even with a full manual, 125cc new barrel and piston is my limit so far:)
Keep going we like this.

Cheers - I agree that it's daunting, but in reality, all I'm doing is unbolting shit, figuring out why it wasn't working, then bolting it back up.

(yes, there's a bit more to it than that, but if I can do it, I'm sure anyone else can! )

The scary bit for me is the timing.... mainly becuase although I have lots of sources for information, as far as I'm aware, no-one has ever assembled these parts in this manner before (the 350 crank in the 500 engine), and I have no idea how much fiddling about with the timing my Dad did when he got it running. It's the ignition timing that I have no clue on. Dad didn't leave any notes!

[Buckaroo]

Ask Millyard. I bet he'd love this challenge. All us watchers certainty do

[Rockburner]

More grinding...



(forgot to block off the timing shaft oil feed... oops )

Progress:


Checking with a 1/2" wide rule


Checking with a 1" wide rule


The cleared area needs to be around 4/5" from the shaft - approximately.

Almost done....



After all that I stuffed the wheels back into the timing side case... and it's STILL "just" touching that odd ovoid shape in the cases with no shim in place - and it's just the outer parts of the ground area (there's a distinct double touch I can feel).

However - there WILL be a shim in there and when there's a shim, there's no touching. So that's gone relatively well I think.

I buttoned up the cases dry again and without any shims to check the end float, and conrod centrality, with the intention of fitting shims not just for good end-float, but also to get the conrod as central as possible.

Overall end float with no shims :


Using the case joining line as the "centre-line" for adjusting the conrod centering. There's nothing else on the cases that is machined in any way so that it could be used for an accurate measurement for centre-ing the conrod: ie, there's no matching face or point on either side that I can use to measure the offset to the conrod and get a balanced measurement with any accurary.
This is with the wheels as far "left" as they will go:


This is with the wheels as far "right" as they will go (the rule hasn't moved).


So - need to play with this a bit more, figure out the shims and tinker, then rebuild again.

Over night I also had a nasty though that I may have put the output side case on without the main bearing pins and carrier... D'OH! So I'll be checking that end-float again!

I think I'm getting a little pressured and starting to make stupid mistakes - so need to try to slow down a bit and be thorough.