Insufficient oil to head? Low Pressure (3 start) oil pump 1962 Norton 650SS

Britstuff

Britstuff

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Having a possible problem with oil supply to the head of my 1962 Norton 650SS. I thought I had this possible issue resolved several years ago, but recently suffered a stuck exhaust valve which is making me question if all is as it should be.

Am running a Norvil high output oil pump with three start auger. Oil supply to the head is via the scavenge return pipe. Rocker spindles are scrolled, with the flats facing inwards.

Oil flow return to the tank appears to be healthy, the oil is full of small bubbles which I take to be a sign of a healthy oil system. I disconnected the oil feed pipe to the head from the y shaped union to observe flow rates. The feed to the head is a mere dribble, even when giving it some revs. Is this normal????? I can put my finger over the return hole in the oil tank and that greatly increases the volume of oil delivered to the head. Amount of oil being delivered to the exhaust valves appear to be quite meager.

In the past I constricted the output of the 01.9380 oil tank return adapter down to about 1/8", (please see picture attached). I am thinking about constricting it further. The manuals talk about substituting in a Jubilee return pipe adapter, that apparently has a more constricted aperture, but which
I think are now hens teeth. Any thoughts regarding aperture dimensions, flow rates, or tales of previous related experiences would be much appreciated.

Cheers,

James
 

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Triton Thrasher said:
A buildup of coke on the valve stem can cause sticking.

Can originate from rich mixture or oil burning.
Click to expand...
Hi:

Thank you for your comment. Yes, very possible, it may be that I am barking up the wrong tree. I just want to make sure my my oil delivery to the head is normal.

Cheers,

James
 
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Britstuff said:
Having a possible problem with oil supply to the head of my 1962 Norton 650SS. I thought I had this possible issue resolved several years ago, but recently suffered a stuck exhaust valve which is making me question if all is as it should be.

Am running a Norvil high output oil pump with three start auger. Oil supply to the head is via the scavenge return pipe. Rocker spindles are scrolled, with the flats facing inwards.

Oil flow return to the tank appears to be healthy, the oil is full of small bubbles which I take to be a sign of a healthy oil system. I disconnected the oil feed pipe to the head from the y shaped union to observe flow rates. The feed to the head is a mere dribble, even when giving it some revs. Is this normal????? I can put my finger over the return hole in the oil tank and that greatly increases the volume of oil delivered to the head. Amount of oil being delivered to the exhaust valves appear to be quite meager.

In the past I constricted the output of the 01.9380 oil tank return adapter down to about 1/8", (please see picture attached). I am thinking about constricting it further. The manuals talk about substituting in a Jubilee return pipe adapter, that apparently has a more constricted aperture, but which
I think are now hens teeth. Any thoughts regarding aperture dimensions, flow rates, or tales of previous related experiences would be much appreciated.

Cheers,

James
Click to expand...
I had a sticking exhaust valve on my bsa b33 , oil feed to head via the return to oil tank , first i increased the size of the banjo bolt hole which was incorrect (very small) anyway it's supposed to be 1.1mm but my exhaust size is 1.7mm now and intake side 1.2mm I have oriented my rocker spindle so that it spurts toward the spring , I have also pushed a piece of copper wire into my oil thank return hole and then just wound it around the tube to hold it there . Also I know Commandos have to have the shafts the correct way around, I think it's oil holes outward . Not sure with your motor , try some stuff to increase the oil flow . Cheers.
 
I made an exhaust valve guide for my BSA b25 engine once
Like an idiot I never gave it a slight counter bore
This caused the valve to stick every now and then because of carbon build up on the valve
I'm wondering if you have the same problem
 
Question. If fitting an oil filter in the return line, does the head flow increase so much that you get a problem?
 
Thank you all for your helpful comments!

I have been conducting a few more experiments...

I swapped out the oil pressure relief valve for a Commando one I had laying about, (I believe and it looks to be the same as the original dominator one). Shimmed it for minimal rattle. This seems to have helped somewhat. The intake valves now appear to be getting sufficient oil, but the exhaust valves are still quite dry. I replaced the exhaust rocker spindles with some older, (lightly worn) ones. Now I have a very light trickle of oil from around the thackery washers down to the base of the valves. Definitely an improvement, but I was still expecting more. Maybe I am expecting too much from the low pressure system? Either way I will continue playing to see if I can improve the flow any.
 
I fitted a jubilee size restriction and found it to give too much oil. gradually drilled bigger to get what i wanted. Would have thought the bigger pump would do the job ,unless also supplying drilled con rods?
 
norton bob said:
I fitted a jubilee size restriction and found it to give too much oil. gradually drilled bigger to get what i wanted. Would have thought the bigger pump would do the job ,unless also supplying drilled con rods?
Click to expand...
Do you by any chance remember what the size of the jubilee sized restricted hole was?
 
I think my oil supply issues to the head are now resolved. Thank you all for your helpful comments.

I found a couple of oil supply issues I have now addressed:

1. I treated myself to an SRM pre-tested oil pressure relief valve. Immediately noticed the oil flow return to the oil tank was increased. Using an oil pressure gauge I borrowed from a friend, the oil pressure is now a healthy 10-50 psi when warm.

2. I identified an oil flow constriction at the Y shaped rocker oil feed assembly on top of the head, (NM25192). I imagine with a pressurized system it would be o.k. but with the low pressure feed it was slowing flow quite significantly. I ended up putting the oil feed bolts (NM18101) on a lathe and filing them to increase oil flow capacity, (please see picture). Major improvement!

Not sure why I never noticed the above issues before. I suppose a stuck valve makes excellent food for thought.

I think insufficient oil to the head was the primary reason my exhaust valve stuck. However, it may also not have been helped by the fact I was running stainless valves, (valve guides are bronze, although I do not know what type). I have now gone over to some much nicer chromed and stellite tipped valves from Norvil.

Thanks again!
 

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Britstuff said:
I think my oil supply issues to the head are now resolved. Thank you all for your helpful comments.

I found a couple of oil supply issues I have now addressed:

1. I treated myself to an SRM pre-tested oil pressure relief valve. Immediately noticed the oil flow return to the oil tank was increased. Using an oil pressure gauge I borrowed from a friend, the oil pressure is now a healthy 10-50 psi when warm.

2. I identified an oil flow constriction at the Y shaped rocker oil feed assembly on top of the head, (NM25192). I imagine with a pressurized system it would be o.k. but with the low pressure feed it was slowing flow quite significantly. I ended up putting the oil feed bolts (NM18101) on a lathe and filing them to increase oil flow capacity, (please see picture). Major improvement!

Not sure why I never noticed the above issues before. I suppose a stuck valve makes excellent food for thought.

I think the lack of oil was the primary reason my exhaust valve stuck. However, it may also not have been helped by the fact I was I was running stainless valves, (valve guides are bronze, although I do not know what type). I have now gone over to some much nicer chromed and stellite tipped valves from Norvil.

Thanks again!
Click to expand...
Hopefully that's the end of it
 

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