Conway Anti-Sumping Valve A65V

ericg

Well Known and Active Forum User
VOC Member
I have a pressure gauge on the Commando and a piece of clear tube on the Norvin and the Comet special as on Eglis so I can see oil circulating as soon as the engine is started.
Actually the valve itself can hardly fail as this is only a ball and a spring.
Some grit can be trapped between the ball and its seat and no consequences to the engine in this case.
BUT, if the connection (pipe) between the valve and the pump isn't absolutely air tight the oil will eventually drain and next time you start your engine the valve won't open because there is no oil between valve and pump so no suction.
I think there is no valve failure only badly fitted one.
Marcus idea is great though.
 

Michel

Well Known and Active Forum User
VOC Member
I have such a valve on my Commando for the last 31 years and about 40 000 miles same on my Norvin 12 years and about 28 000 miles.
No problem so far so I have fitted one on my latest project which a Comet engined special.
What does fails on your valve Michel? And how did you know that there was a problem?
Hello Eric, the problem was easily diagnosed by noticing that the oil did not return to its tank a few seconds after starting the engine. I disassembled and tried to unblock the valve with compressed air without success and I was unable to disassemble it either. Then I forgot the valve which disappeared with other old parts to the dump. The mystery will therefore remain intact.
 

ericg

Well Known and Active Forum User
VOC Member
Hi Michel,
I presume you did fit it the correct way ie with the arrow pointing to the pump.
The valve is two parts screwed together, you can put one end in the vice (not too tight) and unscrew the other end with a good fitting spanner.
I've found that there is no way to open the valve by blowing air to the inlet side but you can easily open it with a slight striving with your mouth.
If you want to try it again you can use a bit of good fitting (for air tightness) clear pipe after the valve so you can see oil flowing as you start your engine.
Again if this pipe is air tight there is no way for the oil to drain down between the valve and the pump.

After all, thousands of Velocettes have done millions of miles with factory fitted anti drain valves without problems.
 

Marvel

Well Known and Active Forum User
VOC Member
I could never bring myself to trust a so-called anti-sumping valve so fitted a manual ball valve on the outlet from the oil tank. It’s barely visible but being a bit forgetful didn’t trust myself to always turn it on so I fitted an oil pressure gauge reading the pressure to the big end quill.
 

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