ET: Engine (Twin) Oil Return Pipe Question

Rixon

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Does anyone know the size of outlet hole in the oil return pipe fitted inside the standard Vincent oil tank?

I’m currently adapting a Norton oil tank to fit on the Norvin and it struck me that the outlet hole in the Norton return pipe may not be the same diameter.

I’m not sure how critical the size of this hole is but I may as well be safe and follow Vincent practice.
 

Cyborg

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I was recently pondering the same question and ended up making the hole 1/4”.
I suppose the actual size Vincent used depends on whether it’s a B or a C. Never looked at a D. The C chain oiler setup is different, so that would come into play. This oil tank is in the tail section, so size/ length of hose could be factored in. At the end of the day, I decided it wasn’t really that critical. If for some unknown reason it wants more resistance to shove more oil to the rockers, then I can just add a restrictor to the line, but doubt that will be required.
 

Bill Thomas

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Another thing we don't think about, Till somebody asks !,
Interesting, The hole coming out the tank fitting might be small, But the metal pipe going to the pump is much bigger !, Looks to me like it takes a 7/16 " Rubber pipe .
The metal pipe that the rubber goes on, The inside is more than 3/8" but less than 7/16 ",
Must admit when I built my Special I made it bigger than 1/4", But not 7/16, That was with a home made oil tank, It's been Ok since 1975 !!.
This showing the big standard feed pipe going down between the gearbox cover and the Timing case.
 

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Rixon

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Just to reiterate - I'm referring to the oil return hole located inside the oil tank. The size of the hole will surely affect the back pressure and, I assume, the oil feed to the rockers.The pipe sizes I'm ok with.
 

davidd

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3/8" sound about right for the hole that the pipe fits into. I would think that the holes in the block are drilled to 3/8", which would be perfect for slipping the return pipe into. This should allow a pipe to be inserted in the hole with somewhere near the correct ID for good oil flow. I would think that the Norton should be roughly the same size. A smaller ID does cause a slight restriction, but the oil will move faster through the smaller size tubing. The viscosity of the oil you run will also determine how much restriction there is in the system.

The locking rocker feed bolts should have no problem with an increased supply of oil passing by. It is always good to make sure that the area around the guides drains well. It does not sound like the pipes or any restriction should cause problems.

David
 

Pushrod Twin

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These 2 holes in the UFM? They would be a nominal 1/4" inside. Made from 3/8" OD tube x 1/16" wall = 1/4"ID

I couldnt get a piece of 6mm, .230" round to enter but a piece of 5mm .198" flopped around so I would suggest that the 1/4" hole had shrunk around the welded area.
 

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Chris Launders

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Also the standard return is much higher than an oil tank on a Norvin would be, the one on my Norvin I just put a 1/4 BSP fitting on the central oil tank and the standard pipe size into it, no restrictor.
 
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