ET: Engine (Twin) Oil Return Pipe Question

Rixon

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I'm using a standard Norton oil tank, not a central one.

These have an internal fixed return pipe which terminates in a flattened end. The return oil is allowed to "escape" via a hole drilled in the pipe wall.
 

Cyborg

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Siting around watching red insulating varnish dry, so made up a go/no go gauge at .250”. Just fits into the hole. C tank with the chain oiler which taps in there.

Hole in the B tank is pointing towards the side of the filler , so can’t measure accurately, but it is slightly larger and slightly oblong.

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Chris Launders

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I know you are using a Norton tank and I am familiar with them having had an atlas for the last 36 years, I was just pointing out on my Norvin I didn't bother with any sort of restriction in the tank.

I don't know the size of the hole in the Norton return pipe inside the tank off hand and I don't use mine anyway, I have a cartridge filter in the tool box and the return from that goes straight across into the oil tank, the original return pipe is blanked off.

Would all Nortons have a restriction in the return pipe, surely the ones with the pressure fed rocker set up wouldn't need one ??
 

Robert Watson

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I don't believe there is a restriction in the Vincent return line. The metal tubing bits are 5/16 tubing with the appropriate rubber hose over top and 1/4 bsp threaded fittings. the tube going from the banjo on the bottom of the oil tank to the block in the filler neck is the same 5/16 tubing with a 1/4 in ID one finds elsewhere in the oil return system......
 

timetraveller

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The answer, dear boy, is a twin start oil pump. Without a deflector to aim the issuing oil downwards inside the oil tank filler neck it will rush out so quickly that some will issue from beneath the filler cap.. No longer a drip not even a spurt, just a good flow once above a couple of thousand rpm. So much more satisfying.
 

Marcus Bowden

VOC Hon. Overseas Representative
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Plus a Honda oil pump supplying into the gallery and cylinder lubricators blanked off, cams and followers have done over 300k so I know it works, it's just big ends I have to keep replacing. Plane bearing floating bush is what I've just put into an "A" comet with the supply pump increased to 3/16" wide delivering half as much again. On post-war Comet's, I'm thinking of increasing the size of the Honda pump and directing it all into the filter housing so it gives a constant supply with mechanical seal to the main shaft possibly restricted as I like to see at least 8 to 10 psi to cams, normally running at about 1 Bar. As for modifying a twin to plain bearings is yet to be thought about. Never have I replaced a ships B/E bearing and they do hundred's of thousands of "hours" lasting 25 to 30 years that I've sailed on!
Roller B/E's take little oil but the contact surface is bearly measurable.
 

Rixon

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Just measured the outlet hole (oil return line) in the Norton oil tank I'm using and it's 1/8" diameter. Based on the feedback I'll be modifying it to 1/4". Thanks for all the useful info.
 
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