Lapping Inter head/barrel joint

…for the advice, much appreciated. I have it dismantled now and it all looks fine but with the spigot 0.002” less than the recess so I’ll re-lap as per notes above starting with the flange face only and blueing as I go and hopefully with a bit of care and patience Bob will end up being my uncle.

cheers, Bruce

…was sitting on top of four identical thickness washers… I reassembled minus the tube as per G Cohen practice to clock the drive shaft vertical float before touching the head - 0.051”
I think I read somewhere between 0.010 and 0.030 being the range to aim for but will check when the time comes. I didn’t bother measuring again sans washers but will check everything thoroughly once the head joint has been finalised. I suspect the washers were added to assist rocker/valve contact angles and opened up the shaft clearance, but as I say will eyeball and measure as I go once the head and barrel are back in place and brace myself for the likelihood of having to adjust the Oldham clearances (cue another thread…). Point taken re. making sure the cam box sits squarely on all four feet Jonathan, thanks. If it doesn’t what’s the method to level it all out… shims?

As an aside, my first Norton in the early 1990’s was a featherbed ES2 and my father (I was a rookie mechanical observer at this point) had a real job getting a reliable head joint with the aluminium gasket.

…the washers Franks is referring to are those in the top head recess for tightening the head bolts against, which are present and correct. The four that I discovered were fitted between the cambox and the top of the main studs from the crankcase mouth which the cambox sits on, the ‘posts’ if you prefer. Looking at the exploded diagram these washers aren’t part of the original assembly and as I understand things are a common workaround to achieve either acceptable shaft clearance or rocker/valve strike angle, or a bit of both. Despite the fact they aren’t original, I’m keeping an open mind as to whether or not to re-fit them again depending on how it all maps out. Although I’m happy to listen to any advice on this. All the posts and head bolts are match marked already which I’m sure is a good sign.

I’ll keep an eye out for the seal adjusters David, thanks for highlighting that. My cambox has had adjusters added to the top as well, not sure if that’s regarded as a good or bad thing, I’ve yet to open it but intend replacing the wiper seals while it’s off.

The bike is new to me, and although I wish to treat it with due care, I’m really just keen to get it running nicely, put a few miles on it in the spring and work it all out from there as there will undoubtedly be a lot of wee niggles as it comes back to life. I get the feeling it’s done next to nothing for decades and although the top end was re-done at fair expense in 2014 by someone apparently well versed in SOHC rebuilds, it has only covered 8 miles since and I think I’m mainly dealing with the old enemy of degradation due to time and lack of use. I’m only saying all of this as a line in the sand as to where I think I am in space with it and what my hopes are.

… It might sound like I know what I’m up to, reality is I just think I know what I’m up to at best, sometimes I don’t really know how to approach a task properly at all, and seek the approval or warnings or advice etc. of all of you chaps who have been there many times before. I find this forum and a few similar for other machinery a great source of help and encouragement, and caution, in equal measure, and appreciate it very much. Up here in Scotland specialist ‘help at hand’ can often be scarce so it’s beneficial to be as competent as possible, fortunately I enjoy it too. Points noted above re. Cambox legs, I’m going to make a start to the head joint prep this week and take things from there.

cheers, Bruce

Good news first. Success with head joint, motor goes well, Stu Roger’s cam tube o-ring and spacer seal set-up works a treat, I’m even slowly working out how to start it (this one has a great thirst, you need to get plenty fuel in there). And I even had my first 2 mile test run. Footrests are a nightmare, gear change so very difficult, the gap between first and second is breathtaking… but all tweakable given time and miles and familiarity.

More pressing (and the bad news) is the oil pulsing out of the cylinder base, mostly by the near side rear stud. It’s excessive by anyone’s standards. I’ve done a few ‘clean up and look again’ tests with a slave fuel tank, torches, and strategically stuffed tissues, and it’s definitely eminating from the base upwards, presumably the rear cylinder feed, and is moving out under pressure. My bottom barrel joint assembly was simply a thorough clean of faces and spacer, and two new base gaskets coated in grease. That was maybe wishful thinking and I should have used sealer. I made sure the gaskets were clearing the oil feed holes in the crankcase. The rear oil feed screw was over two turns out, half a turn out didn’t stop it. Screwing home fully did.

And so, the next raft of questions. Let’s ignore the prime suspect of the base gasket joint being the culprit for the moment… as that’s the obvious place to go but I wish to think about other causes before dismantling it all again so soon…

Pressure relief valve - is it possible that if the ball was stuck on its seat the pressure could be so great to the rear cylinder that it could overcome the gaskets rather than simply over-oil the piston and/or push excessive oil up to the cambox? My barrel has four drillings.

And in the likely event that the barrel has to come off again, do I need to re-lap with the head or just clean and reassemble?

Should I have used sealer at the base joint in the first place?

Any other thoughts as to possible source of the trouble?

cheers again, Bruce

…is fitted with a thick-ish locknut and a fibre washer.  Looking at Paul Normans online shop the locknuts are made purposely thin. I’m guessing now, but it seems logical that the elongated pin on the screw that goes through the spring should be able to push the ball firmly against it’s seat in the case (ie clamped shut) and that this is the ‘screwed fully home’ position? Then turn screw back 2.5-3 turns and lock, allowing the ball to then pop that small pre-set distance off its seat as oil pressure overcomes spring pressure?

with the locknut wound fully out against screw head mine feels like it’s tightening against the fibre washer as opposed the ball, which may well explain why I’m seeing this excess oil to the barrel - in that once screwed ‘home’ then adjusted back out, the screw is in actual fact much more than 3 turns out from the ball being clamped so the spring is in less compression and will allow ball to open under less pressure, with a bigger opening, more oil through? Is Columbo right on this occasion?

Just one more thing… thanks again to all for the advice.

cheers, Bruce

...since getting back onto the business in hand after numerous life distractions. Though there are still questions...

First of all thanks again for all the help and advice thus-far. The barrel is back on and bottom spigot has been successfully sealed, new oil pressure spring fitted, kept old ball for now although I bought a new one. Similar story with the adjuster screw as the old one seemed a much more pleasant fit. Chucked fibre washer away, adjusting inwards hard against ball then back out and locking is now easily achievable. Head joint is holding together fine too.

so, after 30 miles of tentative riding including a single sustained 15 mile stretch and having bolted a few wayward items back into place, things appear to be going in the right direction. Although the piston and rings are new and need run in It feels very strong indeed, a bit buzzy maybe, but nice and lusty. It still likes to fling a little oil around but it looks like it's almost all from the valve gear which will remain on monitor for the rest of the season. Gear change is miles better after a bit of footrest/gear lever/kick start jiggery-pokery. It makes a wonderful noise. It's even reasonably comfortable. I like to think I have starting sussed but then do I? I've never tried with anyone watching. And then there is the next problem to work out.

Once travelling, if I give the throttle a big wind open we are rewarded with a rather loud and sustained 'chirping' sound from, I am sure, the carburettor. Roll back off a fraction and it goes, roll on and it's back. Any ideas why this might be? It is very prominent and a tad disconcerting.

cheers
Bruce