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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!
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