1962 Norton Dominator 650SS Hi Pressure Oil Feed To Head Conversion

Hi All:

I am toying with the idea of changing my low pressure drip oil feed to the head, to a high pressure one like on a Commando, (and other post '66 Norton heavy twins).

Is an upgrade to a six start gear and worm an essential part of the recipe?

Some back ground information:

It has been quite a long journey trying to get an adequate oil supply to the exhaust valve guides and tips. Have recently suffered sticking valves, a snapped exhaust rocker and major deformation to the top of the exhaust valves. Through it all intake valves have been just fine, plenty of oil, no problems. Funnily enough all was acceptable until I fitted an anti-sumping oil tap. I think the fact that the bike was wet sumped most of the time when I started it, caused a nice strong initial oil feed to the exhaust valves before the sumping was cleared. I suppose I could put my finger over the return hole in the oil tank for a minute or so whenever I start the bike. I'm just thinking why keep messing with it? I like my anti-sumping tap, My MKII 850 Commando runs so much quieter and without any problems with oil delivery to the head. I have a Norvil high Capacity, (whatever that means) oil pump fitted on the '62 Dominator. Still running the three start gear and worm. When I run a pressure gauge from the high pressure outlet, below the pressure relief valve, I get excellent oil pressure, (warm 20-50 psi).

A concern I have with my proposal is possible over oiling to the head. Being a '62 I am guessing the oil drain drillings are smaller than the factory post '66 hi pressure feed bikes. I assume we are talking about the single drilling oil drain for the intake valves - to my tiny mind it appears to be quite small.

Rockers are all in great shape. I would definitly install plain spindles with the flats correctly orientated. Oil feed to the head from the high pressure outlet, below the pressure relief valve. I already have inlet valve stem seals fitted. I'm just wondering if the six start conversion is a neccessity? some sources seem to suggest it is not, but, obviously I do not want to risk compromising oil feed to the crank.

I look forward to your comments.......

Many thanks!

The high output pump and 6 start gears will dramaticaly increase the oil supply , It usually results in an excess to what the valve sealing (?)! can resist. and will overwork the pressure release valve to the detriment of the mag or distributor. Extra oil flung up from rods may give the simple oil rings a hard time , the pump will wear at twice the rate . The alternative will be to stay with the 3 start set and adjust the hole in the tank return fitting to send a bit more oil to the head . I fitted a brass insert and drilled it out in stages till i got what was needed , signs of oil in the ex valve area. Better tappet adjusters are sold.

Thank you @norton bob for your comments. I have also played around with various sized tubular inserts in the return to the oil tank. Doing so definitely helped, but results remain inconsistent. My idiot test is if I see signs of oil on the top of the exhaust valve springs after a run, all is likely ok. Unfortunately it is rather hit or miss. On any given day either one or both exhaust valves seem to be running dry. The head is currently off for the third or fourth time. Be it in the past to replace exhaust valves or guides. I just fancy trying something different, instead of repeating the same and getting the same result. Currently the only way I can get a good squirt to the exhaust valves is when she is wet sumped or if I hold my finger over the oil tank return hole for a good minute or so. Frustrating, as the strength of the oil return seems to be good and I examined and played around with the feed to the head to the point it seems to also be good. I am running what I think are some pretty decent mushroom tappet adjusters.