Lack of oil to rocker box

YES First who rebuilt the engine and where have you fixed the oil pipe too , the tank or the back of the engine case ? all-so there are oil ways in the cylinder head have these been cleaned ,As it seams to me there is a blockage somewhere in the head or oil pipe ?and as the return oilway at the back of the barrels been cleaned are is a dogleg in the crankcases that matches up with this oilway , and it gets blocked too ? yours anna j dixon

Hi I had trouble getting oil to head on my dommi 99 flowed there for first 5 or 6 miles then stopped,tried allsorts,checked all lines were clear,tried another pump,even tried a smaller restriction in return line ,all failed then I noticed a race bike with another breather from rear valve cover,I had a spare so welded an aluminium pipe to this and ran another breather this fixed my problem,so there must have been be too much crankcase pressure ,and the oil takes the easiest path back to tank. hope this helps cheers barry

Previously wrote:

My 1960 model 99 Dominator enginehas been totally rebuilt. It seems to have intermittent oil starvation to the rocker box.The oil seems to be going straight back to the tank instead of up the rocker box feed. Can anyone help please?

There are quite a few possible reasons for this kind of problem. As Anna says, clogged up feed holes in the head can restrict the flow. Also over-pressurisation inside the rocker boxes does not help.

Try running the engine with one of the rockers covers removed. If the flow improves then fit a breather in one of the coversto help. You don't have to weld one in place. You can drill and tap the cover for a threaded pipe union such as used on twin carb spacer balance pipes.

Norton's recognised that the feed to therockers became a problem when the oil pumpbecame very worn and the return pressure to the tank then could not handlepushing oil above the tank level. This was one reason the later engines had a pressurised rocker feed. John Hudson suggested restricting the return flow by fitting a restrictor from the Jubilee model in the plumbing just before the oil tank. A thin washer with a 2.78mm internal dia will doa similarjob.

On my old Atlas, I took a 120mm length of 6mm bore plastic tubing and then slit this along its length on one side. This was then put inside the oil tank and slipped over the return pipe, covering the outflow hole. This had the same effect as covering the hole with a finger, which all the smart owners do anyway, on start-up, after a long period of non engine-use. OK, this was not precise mechanics and probably put too much oil back to the head when the engine first started but it worked for me as a short term fix before I refurbished my oil pumpwhich thensolved the poor feed problem totally.