SOHC.co.uk Forums > The Black Bomber Board
Black Bomber valve clearances.
royhall:
--- Quote from: K2-K6 on June 28, 2019, 06:38:06 PM ---It looks like they're not familiar with that adjustment geometry specific to this engine at Newman. With a conventional screw type it could accommodate that change.
Worth taking into consideration for anyone else in same situation, unfortunately of little help here.
--- End quote ---
I have at least found the problem so am happy about that. And I can put it right without having to strip the whole lot down again. Newman Cams said they had removed a very thin skim, from what I can see and measure that looks close to 10 thou plus whatever they took off the cam itself. That's a lot for the mechanism to make up, and it simply does not stretch that far. Your correct in saying they probably aren't familiar with the layout. Just unfortunate and another one of those things to watch out for, and partly my fault as I should have taken measurements before and after. O well, it's only money.
Bryanj:
You could fit what the yanks call a lash cap on the valve stem, its like a small hardened dustbin that fits over the end of the valve stem.
Laverda Dave:
I had a similar issue with the 250RS Roy. Newman advised me to send the cam and the rocker arms. They ground the cam and welded pads to the rockers to take up the bigger clearance. From your experience with Newmans compared to mine (earlier post) I think it depends who you get to speak with at Newmans determines the level of advice you receive. I've always been lucky and have spoken with Mike Newman who obviously knows his onions (and cams!).
Good to hear you have the problem sorted now.
royhall:
--- Quote from: Bryanj on June 28, 2019, 10:48:19 PM ---You could fit what the yanks call a lash cap on the valve stem, its like a small hardened dustbin that fits over the end of the valve stem.
--- End quote ---
That's an interesting idea Bryan. On this occasion though I think I will replace the rocker arm as any other way is just treating the symptoms and not really curing the actual problem.
Bryanj:
I just hope they didn't take so much off the lobe that a new follower wont close down enough. Have you told Newmans about the problem as they ought to fix it for free really.
I remember many, many years ago talking to an engineer who raced (250 K3 I think), he had a cam made and hardened it with the result it lasted less than 100 miles, apparently cams were meonitic cast iron with followers hardened and you should never run two hardened surfaces together
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