Troubleshooting a JAP Special

[Rockburner]

Interesting conversation with the Guru this afternoon....

I hadn't realised it, but that banjo "post"  fitting has a counterpart in the Pilgrim pump outlet, which is BSP as standard, and the Rocker box fitting is BSC as standard.

Here's photos of the 2 parts from the supplier...





Apart from the machined channel on the upper part.... they're both nigh on identical banjo fittings.  It's quite within the bounds of probablity that the BSP pump outlet part (the lower photo) has been modernised to have the channel cut into it to improve oil flow and that photo is of an older style part, so the parts would look virtually identical when you're just picking them up and throwing them into a package.

So it's quite likely I've just been sent the wrong part...  hey ho, I can easily see a mistake like that happening, we'll see what they say at the suppliers....

[cardan]

Weirdly I was working at my bench this afternoon when I noticed a banjo fitting on the (very messy!) windowsill. I measured it: 1/8 BSP on the screw-in end and 3/8 BSCy on the nut end.

I have an Australian-made bike with a Spacke De Luxe engine, made in the USA. One of the fittings the oil pump is 1/8" NPS, which is major diameter 0.405", 27 tpi.

So 0.375", 0.383", 0.405"... 26, 28, 27 tpi... you've got to love a good thread.

Leon

[33d6]

Learning about various thread forms is one of the great entertainments of ancient machinery (not just motorcycles). In the early days of the automotive industry there were three great centres of industry, USA, UK, and Europe. Of which Europe had several major subsets, France Germany and Italy with activity elsewhere on top of this. None of these areas really spoke to each other. They couldn't, there was only surface post and ships, let alone all the different languages, even friendly and helpful communications took months so all played alone. All had the same problems. All had much the same knowledge base, machinery, metals and men to work with and all invariably came up with much the same answers to their problems but not quite hence the weird mixture we find today.
Everyone has known the need for standardising these things for over a hundred years but we haven't managed it yet and I doubt we ever will. Human beings can be remarkably contrary.
Working on an old motorcycle is just a pleasant way of learning all this history and ain't it fun.

PS
Just be glad you haven't had to dive in to metric stuff. That's another world of mystery all of its own.
   

[Rockburner]

Oh, this bike has everything on it. Including proper metric, not just BA (which is metric thread believe it or not!)

[Rex]

A metric spec, but clearly not a metric thread.
I read somewhere many years ago that the early US loco's (the ones always featured in Westerns) used Imperial threadforms until US manufacturing and standards caught up.

[Rockburner]

A metric spec, but clearly not a metric thread.
I read somewhere many years ago that the early US loco's (the ones always featured in Westerns) used Imperial threadforms until US manufacturing and standards caught up.

Is that because originally the engines were shipped in from Britain? And further work was then based on those originals? Maybe, perhaps?

[Rockburner]

So, back in the sauna, err, sorry, shed.

I took a look at the Pilgrim Pump banjo unit first, to confirm what is going on with the oil feeds.
This is the feed pipe top banjo fitting:

and the bottom end:


As you can see, neither have a "channel" inside the fitting, so my thoughts are that for decent oil feed, both "male" fittings really should have a channel.

This is the outlet from the Pilgrim pump:


No channel.
So - I figured I could swap to the new banjo post I received inadvertently.


....


Have you ever known anything on this project to be that simple??



....


This is the new banjo post flapping around loose in the Pilgrim pump.


Here they are back to back.


the NEW fitting is 1/8" BSP 20tpi.
the diameter fraction is "internal".... Edwardians!
the outer diameter of the threads is 0.378, (nominally 0.383 according to Zeus)

the OLD fitting is 1/4" BSP 19tpi (wtf?? BSP is weird),
the outer diameter is 0.510 (nominally 0.518, Zeus says)

So - the fitted Pilgrim pump is a weirdo too! ffs.

Luckily I don't need to chase down yet another sodding banjo post, because the old one on the pump is fine.
The new 1/8"BSP banjo will be thrown into the box of useless bits.

I dug out a couple of copper washers for the Pilgrim pump banjo, have I mentioned in the past my opinion of felt washers...





Next job was to try the timing box with some oil in.


Dribbling some oil on the cam(s).


Fitted up with the new pushrods (I tidied up the excess epoxy a bit too, but there wasn't a lot).



STILL clickety clack. 

ffs.

So I took some time to have a damned good look at the timing chest mechanisms, and I still can't really see anything wrong at all.

The inlet follower DOES get VERY close to the casing when the cam is "off", and I was wondering if this very very slight mark was an indicator of that...


There's a possibly corresponding "nick" on the very edge of the boss that holds the camshaft in the casing :
(right in the centre of the image)


So, I took the follower I've designated as the "inlet" and shaved off a tad of a chamfer on the lugs:






I also took a sharp knife and shaved off a tad of a chamfer on the boss in the cases:


Close up:


There's now a significantly bigger gap when the follower is on the lower part of the cam.


Did it make a difference I hear you ask??



...


did it buggery. :roll:

So I carried on with the aim of making the notches in the followers to allow better oil flow to the moving parts.


Advice from the guru was to do both, but make sure they are on "different" sides so they aren't going to interfere with each other.


I'm nigh on giving up on trying to solve this damned "click-clak" sound.  It ONLY happens when the pushrods are in place and under compression from the valve-springs.  Remove that compression and the timing chest is utterly silent when it rotates.

[Rockburner]

Soooo...  a BONUS episode!

I had a bit more time in hand, so while I ponder the wisdom of just forging ahead, I took the chance to look at the push-rod tubes, and also modify my valve-lifter clamp

I read somewhere on FB the other day that the pushrod tubes have o-rings in....
and blow me.. they do!


Actually - that one had 4!  Oddly the other one had only 2!

The modification to the valve-lifter clamp was because I realised that the offset of the forces was still causing me a lot of issues with it, so I err - bodged it to stop it falling off!
First I cut about 3mm from the underside of the clamp, to push the screw further over the top of the rocker box, then I bent a bit of old steel to make a hook to guarantee it wasn't going to pull itself off the box:


It works a treat!



I gave the inners of the pushrod tubes a clean:


O-rings?   no, I can't say I've got more than a few....
( :wtf: where the hell did all these come from??? )



The o-rings are used to pad the bottom of the push rods so they fit neatly into the rocker-box at the top. Ideally they'd be a friction fit, and I've got that.... more or less...
Test fit:



So - if I don't get back into the house I have a nasty feeling my dinner will be served "au visage", so, until next time my oily brethren!

[Rex]

I reckon your vice is as collectable as your bike will be.
What is the intended rolling chassis?

[Rockburner]

I reckon your vice is as collectable as your bike will be.
What is the intended rolling chassis?

See page 1, it's motive power for a Featherbed special build.

The vice is certainly handy!

[Rockburner]

More tinkering today....

I'm still trying to figure out where this clacking noise is coming from, and after a bit of fiddling about, it occurred to me to try rotating the engine within the timing cover off again.  I was trying to figure out if there was a worn interaction in one of the ball joints (either end of the pushrods).

With the timing cover OFF, the clickety clack is NOT there.  Whatever is causing this is only in effect when the Timing chest cover is fitted.

So - I continued trying to figure out what could possibly be happening.

I dug out a 1/2" length of rod so I could assemble the timing components in the cover, rather than the cases (to see if anything was interfereing)

First the rod needed a tad of tidying up. (No idea what it was originally)


It just needed to allow the cam-followers onto it, so rough was good enough.

I can confirm that there's nothing interfering due to the timing cover.



So - with more investigation... we get more information.

And here's a video explaining what I believe i have discovered.
https://youtu.be/HmQjgWlt1uA

So my choices are:
Order a new pair of bushes and in the meantime, strip the entire thing down again, with no guarantee (despite what I believe) that this is a solid fix;
Or:
Accept this slight looseness and carry on, knowing I'll need to strip the engine again at some point soon(ish) and accepting that there'll be a tad more wear happening in the current bushes. I don't know what that movement will do to the rest of the components: ie. what extra wear (above the usual) would be caused by carrying on.

Difficult decision. (I'm currently waiting to see if I can get a chat with the Guru to se what his opinion would be). Stripping the entire engine down would be somewhat demoralising at this point, even though I now know how simple it actually is.  It's more the faff of stripping and cleaning the sealants and re-making gaskets etc that puts me off.

[Rockburner]

Ok - so I had a call with the Guru and he offered some more suggestions for things to check: namely:

1: try rotating the engine with just one push-rod in, see if it's one or the other causing the issue.
2: check the play of the camshaft in it's bushes with no springs (ie whip the pushrods out)
3: measure the wear on the bearing parts of the camshaft spindle (ie where it sits in the bushes.

So - I did those.

1: Each "side" of the timing still has the click noises, but with only one valve in operation I was able to figure out exactly where in the rotation the clicks are happening.  BOTH of them are about 5 degrees after peak cam lift. IE when the cam-follower has "just" passed the highest point of opening on the cam lobe.

2: there is f***-all play in the camshaft when the timing cover is in place, at all 4 cardinal points (TDC, TDC+90, BDC, BDC+90) whatever play there is, is identical.  With a nadger of end-play.  I think the bushes are fine.

3: I measured the cam spindle-ends with a metric vernier, then converted to imperial (see last photo in the post), to get the following:
crank end: 0.003071 under (nominal is 0.5", measurements avg to 0.496929")
mag end: 0.001969 under (nominal 0.5", measurements avg to 0.498031")

I also measured the mag-end bush inner diameter (the one in the timing cover): 0.497"

(I haven't got any means of measuring the crank-end bush without stripping the engine again, and even then I'd only be measuring the outer end of the bush, relative to the spindle).




So, If the bushes are fine, and even though there's a touch of end-play on the cam-followers, there's no other movement on that spindle (you need SOME play to prevent the followers binding on each other), ie both followers are not rattling on the spindle: we are both stumped. 

Even the Guru is clutching at straws now: his last communique was an idea to check the actual cam-lobe for a slight dip at the point the click is happening. IE use a dial guage to measure each lobe as it rotates (preferably in a lathe, but I should be able to bodge up something reasonably solid....)

The really weird thing about this is that the click noise happens even when the crank is being rotated really slowly, so the thought that it's a "bounce" from the momentum of the parts in the system doesn't really add up.

My current thought is to say F**k it and just finish the build and see what happens!  getting bored now...

(as an aside, replacing the camshaft bushes sounds like a right faff... the one in the timing cover needs to be machined after fitting to give the correct end play, and they need to be reamed to size "inline", ie both fitted in place when the engine is completely torn down. I'm quite glad I don't need to do that!)

[Vreagh]

Could it be the backlash in the cam gears when the torque on the cam is reversed as the follower goes over the peak ? This would be more noticeable when turning slowly.

[Rockburner]

Could it be the backlash in the cam gears when the torque on the cam is reversed as the follower goes over the peak ? This would be more noticeable when turning slowly.

The current thinking is that its something along those lines.

What's got me confused is that the guy who has done 100s of these engines has not experienced this noise before. If it was something expected like that backlash you'd think he'd have seen it at some point in his career.