E: Engine stop valve assembly

[Monkeypants]

I have worked it out and all is good no more Sumping the problem was T32 oil stop valve was completely stuck so I ground it in, now everything is working good I have a little bit of oil in the sump but engine does not smoke when I fire her up and it scavenges that little bit of oil back in the oil tank/UFM so thanks for the info I love solving problems and fixing them, also no more oil tap to worry about wicked. To Vibrac dont worry mt theres always a way worrying dont get you no where. Ash.

The T32 valve needs to be open at all times other than when you are disassembling the bike. It is only there to hold the oil in the tank on disassembly. When assembled the valve must be fully lifted to allow oil flow to the engine.


Glen

 

[Black Flash]

Come on Vincent Speet,

I think it is about time you show your pump to the rest of the Vincent universe!

 

[Peter Holmes]

I have no desire whatsoever to see Vincent Speet’s pump!

 

[Pushrod Twin]

I have heard about that several times, but never tried it myself. The intake port on the pump in fully closed before the pressure port opens. My guess would be, assuming crank position actually makes a difference, if the pin is at the top, the oil is not going to try and siphon out into the sump. If the pin was at the bottom of the stroke, that would help create the siphon effect. I’m reasonably sure some oil finds it way past the quill regardless of crank position. Especially if the timing cover is mismatched and the side of the quill is worn. My Comet sumps fast enough that it would be a good candidate to measure. Drain the sump… let it sit for a week at BDC… drain and measure. Repeat the test for TDC and measure the difference.… but I’m all tested out for a while.

Norton Commando owners insist that leaving their engines stopped with pistons at TDC is the solution to sumping and their explanation is similar, but rather than "siphon" effect, they seem to think it simply prevents gravity pushing oil down from the tank, then back up through the crank pins and bleeding out of the plain BE bearings. I am seriously sceptical as I believe the bottom of a Commando oil tank is still above the crank pins at TDC. OK, having the pins at the top does reduce the difference, top to bottom, hence reducing the "head" or pressure, but enough to stop the bleed???
With the Vincent oil tank strategically placed at the top of the frame and the first obstruction, the pump plunger, near the bottom of the engine, the head pressure is greatest, so the pump has to be the source of the bleed, does it not?? Position of the crank pin would have little or no influence, I believe.

 

[Cyborg]

well…. I could test the Comet and put the theory to bed once and for all, but someone’s going to have to buy me a beer. As noted in my oil pump volume thread, it’s surprisingly easy for the pump to suck in air. Actually…it seems odd to me that there is more interest in sumping than the possibility of air getting sucked into the pump and the pumps (maybe ?) possible relationship with crankcase breather timing. Granted the effect is less imminent. Anyhow…If air can get in, then oil can certainly get out over time. As mentioned previously, the suction port closes before the pressure port opens, so where the oil pump stops shouldn’t really make a difference. However…regardless of where it stops, there isn’t much real estate preventing oil from escaping. Any crap going through the pump is going to create wear on the very area that helps to prevent sumping. Hopefully this makes some sense. I’ve broken my rule about not posting prior to my first cup of coffee.

ps… Thanks Peter. Now I can’t get that frightening image out of my head.