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[K2-K6]

To echo whats been said above, such a shame to get this result from all the hard work leading up to it.

I think we all feel your pain on this one Neilw.

It is an odd one this, if you don't know about it. For those that are unaware, the rockers are best pulled up through the tappet cover holes and linked across the outside of the cover with elastic bands to hold them there while the cover is assembled onto the head. It has the effect of the rocker pads touching the cam lobes first, and not letting the rocker tips "snag" on the valve stems while tightening tbe cover to secure it.

[Neilw]

Thank you for all your support. I now realise the mistake I made, and it's borne from my lack of experience.

I didn't know that the rocker cover should have sat flat on the cylinder head. This wasn't explicitly stated anywhere, so when I fitted the cover and it sat about half an inch above the head, I thought that I should just tighten the bolts uniformly down until they met. Which is why I managed to bend all 8.

I guess, if I had been more thorough looking through the manuals, I may have spotted the bit about holding the rockers up. Note - none of the videos I watched on YouTube explained this!

So definitely a lesson learned.

Now onto sourcing a replacement head.




 

[Oddjob]

I’m not of that opinion Neil. To bend all 8 I think you got the cam timing wrong. Maybe you finally got the chain on the sprocket and then moved the cam to align the bolt holes. Just a theory but would explain the results better than just snagging the adjusters on the top of the valve stem, 2 or 3 , yeah I’d say possible but all 8, mmm not sure. I think as you rotated the engine afterwards that’s what caused the valves to hit the pistons and explains the noise you could hear as well.

Either way, damned bad luck and I’m genuinely sorry you learned that lesson the hard way. If you hadn’t broken the guides I may have had 8 spare valves somewhere. I know I’ve got over 50 good cam followers in a box of oil, I even threw around 20 away. Never thought I could get them repaired with hard chroming. Live and learn eh.

[McCabe-Thiele (Ted)]

This is the trick to hold the rockers in place when you fit the top, one rubber band does a pair of opposing rockers, the adjustment screws were undone as much as possible.

I learnt this from NJ's rebuild
WP_20181111_16_44_15_Pro (2) by Macabe Thiele, on Flickr

[Neilw]

So an Update with some good and bad news!

BryanJ came to my rescue and supplied me with a replacement cylinder head with intact valve guides and a good set of valves.  I've spent many days preparing, cleaning, painting and finally honing the valves, and everything seems good. Installing the springs with new valve seals went smoothly, and today was the day to fit the head and move forward.

I've had the head on and off twice, as I discovered that the front flange holes were blocked with some form of calcification, which I cleared with a reamer; all good and refitted.

I've torqued all the head bolts down, and I have now discovered that the flange bolts should have been torqued less (thanks, Haynes manual, for not mentioning that). As a result, I over-tightened the front flange bolt and stripped the thread in the lower cylinder head. It's not entirely gone; I can get it finger-tight, but no tighter.

So, now what are my options? Is there a diy fix? will it do as it is, as all other bolts are torqued correctly? I'm not quite sure how to proceed and whether i'm able to do it myself. The lower cylinder has been bored out, and i have new oversized pistons fitted, so i don't want to replace it.

I could cry!

[Johnwebley]

Helicoil will sort that


No hassle, just extra work

Those small bolts are prone to stripping

Sent from my SM-A546E using Tapatalk

[Bryanj]

Yup 6mm helicoil kil, not too expensive and you will use it more

[Neilw]

Phew, another new skill to acquire!

Anything to watch out for when buying a kit - i see cheap ones on ebay are they any good?

[Laverda Dave]

Buy cheap and repent at your leisure! Things are normally cheap on eBay for good reason, 90% are absolutely crap! I bought a 90deg screwdriver to adjust the carbs on the NC30. A Seeley screwdriver was £40! I bought one on eBay for £12 and it lasted all of five minutes. It was so cheaply made inside the cable stripped as soon as I tried to adjust the balance screw that has a spring behind it, it is now in the bin and I've bought a decent Seeley item that I should done in the first place.
A good helicoil kit is made by a company called 'UniThead'. They should have a website. You get the full kit in a plastic box, worth the money and always works first time.

[Bryanj]

With tools i would agree but i bought one of these about 3 years ago and so far bought over 100 coils extra, there is a nice tap holder i got as well if i can find that i will post it seperate

[Bryanj]

The wrench i bought isnt for sale at moment but this is similar, means you dont need room for a standard tap wrench

[Neilw]

Just a quick update - and i've had a good day!

I purchased a Helicoil kit and thought I might be able to drill the holes while the cylinder head was in the frame. I decided against it due to access restrictions, but also so I could do a proper job.

I did front and back flanges to ensure no ongoing issues and, if i say so myself, did a good job, so one happy bunny.

Fitting the main cylinder head was straightforward and then the new head. All torqued down correctly, including the two flange bolts into their new Helicoil homes.

Fitting the chamshaft/chain was fiddly, but nothing like the whole day it took me last time, maybe an hour of messing around. Also made sure that 1 & 4 were at TDC and the slot was located correctly, which will save me time when i get to setting the tappets.

So i'm now back to where i was 4 weeks ago before i screwed things up.

I'll tackle fitting the rocker cover tomorrow afternoon.

Thanks for all the advice to get me this far. ALso have a set of Elastic bands care of my postman, ready to use. Fingers crossed.

[McCabe-Thiele (Ted)]

Most of us have experienced Groundhog days at one time or another, well done with your pereverance.

[Johnwebley]

Good for you

Can I suggest you completely remove the tappet screws and lock nuts,

Lol

Obviously the nuts stay on the tappets!

Get a card,8 holes

E1 to 4

I1 to4

Keep them in the same position

Keep up the good work



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[Bryanj]

Well done, only a couple of hints
1 make sure cam is right way round so the tacho drive works, i am NOT admitting to why that one

2 some jointing compound under the pontefract cakes or pucks as our us cousins call them!