anti sumping valve

[stumpy lord]

Hi,
conways sell an addition to enable you to do that,this probably comprises a banjo union, a lump of hose, and a speacil extended banjo bolt that will open the oil tank drain bolt.
what you then do is disconnect the oil feed pipe at the oil tank, and using your new drain pipe as above, fit it to to the oil tank stop valve, the extended banjo bolt opens the stop valve, and away you go.

 

[Kevin Fowler]

G Day, Thanks for the input as usual I am not on my own. I will instal the valve as per Conways instruction at the next oil change. I will report back

 

[vincenttwin]

I have have had a Conway Valve on my A single for 10 years ,seems to work well ,but like any vintage bike with no oil pressure gauge after starting I always take the oil tank cap off to check the oil return (common sense I hope) . yes a very weak oil pump might not pull open the ball and spring which I think is the case of Robins red bike in Ireland ,even with the anti siumping valve taken out ,the oil return to the tank seemed very weak.
A on-off tap would of course stop any sumping , but if you forget to turn it on ,bye bye big end.
cheers
Peter Allen

 

[derek]

Although I know that a lot of theories have been given, on how the oil drains through the series C oil pump into the cranck-case.
I would like to know if a definitive answer has ever been reached, as it seems to happen even too new oil pumps checked and fitted correctly?

 

[Vincent Brake]

Guys, working of the valve can be checked over, when one puts a piece of clear oil hose after the valve (I learned from Peter V) and one sees oil or dont see and get Fxxd

greetings

Vincent Brake Speet

 

[nkt267]

I had another point of view put to me by a very knowledgeable engineer, that the oil can possibly flow around the outside of the pump sleeve into the crankcase if it is not a good fit. This seems to match with a post by clev trev (I think) about putting 'o' rings in the crankcase for the pump sleeve to seat in..John

 

[Tom Gaynor]

I have a new two-start pump, fitted 4 or 5 years and about 10,000+ miles ago. (In the light of experience, I do not recommend two-start pumps: a wholly unnecessary waste of money.) But. It doesn't sump. Maybe I'm just lucky. I do however use the bike regularly, at least 2 or 3 times a week: that must be significant. I can't however say that it sumps much when left for several months in winter. That may be because the oil solidifies...
I followed the tip in KTB, and put a drain plug in the feed banjo bolt (A22). If you've a lathe, it can take all of 20 minutes to do. If not, maybe 30. Draining the oil now means getting it hot (always a pleasure, and much quicker since I lagged my UFM), removing a 1/4" BSF capscrew in the feed banjo bolt, and waiting until it stops running. Easy-peasy...
Every five or six oil changes I bite the bullet and change the filter. I have to say that either there IS no debris in my system, or that the filter is wholly ineffective. No prizes for guessing my assumption.
It's a motor remarkably tolerant of less than perfect maintenance: more evidence of Irving's genius. A Vincent engine will run perfectly well for 50,000 miles from new, with almost no attention. For a car, 50 years on, that's expected. For a motorcycle, 50 years ago, that was incredible.

 

[Kevin Fowler]

I have fitted the anti sump valve, and primed it .and checked for leaks for 2 days. I also fitted a drain point above the valve. I have since done 2 short rides and an oil change.
Very regular checks on the oil return,flow were done, No reportable issues .
All is good. Any one want photos or line drawings , i will oblige.
cheers
Kevin

 

[derek]

Regular checking of the return oil flow only prooves that oil is being returned from the crankcase, but how does it get their? If serious sumping is taking place and the oil under gravity leaks around the outside of the pump sleeve, then when engine is running with the positive displacement pump the leak around the outside of the sleeve under pressure would be much greater. Therefore how much oil is actally going through the filter-to bottom end and cams etc., apart from that down the pushrod tubes. Could this be why so many vincents suffer from excessive cam wear:

 

[timetraveller]

Oh dear! Only the fifth day of the year and I already have to disagree with someone. Derek might be correct in principal but in reality just how much oil leaks around the outside of the pump housing and how much between the plunger and the sleeve? Can we really expect that enough oil is going to force its way through some very narrow gaps to continue to allow the return side to continuously pump oil back through the filler neck when there is a much easier flow route through the intended route? If you were an oil molecule which route would you take?
On the subject of wearing cams; there were a few examples of original cams lasting for decades but these were the rarity. I suspect that the quality control on the original cams was poor. When I started tuning my own bike and those of others in about 1960 I would look through boxes of new MkII cams to find ones where there was not a flat at the start or end of the lift. These flats could be seen by eye. If they could not even get the shape correct then there is no reason to expect that the hardening would be any more competent. The lever action of the Vincent cam design means that there is much more pressure at part of the cycle than there would be if the cams had a straight lift. This cannot help but it is noticeable that Stellited cams and followers do not wear.