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Oil pressure valve help needed

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Oil pressure valve help needed

Posted by Chris willis at July 12. 2017

Problem after problem with this build, please can anybody help, my timing case is on the left, and I found that it was missing the oil jet and spring which I have now sourced. I also needed an oil pressure valve, (spring, ball and cap) so I bought the cover on the right from eBay as I could see it in there, I can't just change the cover as holes are different shown by the blue arrows, the problem is that the ball sits lower in the right case by about 3-4mm but everything fits but also the ball is tight against the cap on my case, would this have maybe had a smaller ball ? Shown by the red arrows, confused, I certainly am

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Re: Oil pressure valve help needed

Posted by John Oldridge at July 13. 2017

HI chris, I don't know the answer to your problem, but I know a man who might !........ Mike P the singles guru,...... he has been more than help full to me in the past, Should be worth a call.

Regards John O

Re: Oil pressure valve help needed

Posted by richard_cornish at July 13. 2017

Hi Chris,

   The pushrod OHV and SV engines were re-designed for 1948 by, I think, Bert Hopwood. this new design incorporated revolving tappets, which after around 1,000 miles were found to have suffered excessive wear, as did the cams. Production was stopped so the tappets could be modified and possibly the timing cover as well. Unfortunately a couple of hundred of these bikes had been made and sold before Nortons realised there was a problem.

   It is possible your ebay cover is one of these early ones as the casting looks slightly different to your other one. Are there any casting numbers on either ? I am not 100% on this being the reason but it seems the most plausible scenario.

Regards,  Richard.

Re: Oil pressure valve help needed

Posted by Paul Knapp at July 14. 2017

Hi Chris, you omitted to say what year your engine is. Your picture of the right cover (dirty one) is the same as my '51 model. Is your model pre '48? when there were some significant changes to the engine.

Paul

Re: Oil pressure valve help needed

Posted by Chris willis at July 14. 2017

Thanks guys, hi Paul it's 55/56 but it's a bitsa, I bought it as a basket case but it's clearly just bits gathered to build a bike, everything fits ok, am I on the right tracks to tighten the cap until it nips up against the ball then turn back 1,1/2 turns from something a read, the case I took it out of would have been about 4 turns, my case is the left hand one

chris

Re: Oil pressure valve help needed

Posted by Paul Knapp at July 14. 2017

Hi again Chris, my interpretation of that ball valve is it ensures a flow of oil to the oil jet which feeds the end of the crank. It keeps the gallery full of oil, once this is achieved, the ball lifts and allows the excess to flood the cam box. I would think, using a ball that fits the seat (and seals) along with using the correct conical spring (the NOC has them) and with 1-1/2 turns out, you would be on the right track.

Paul

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