Keep in mind, these are not Ferrari or Lamborghini engines. Think agricultural. They will tolerate literally decades of abuse, dirt, crappy oil, they run with cracked flywheels and blocks. The rings can have 1/4 inch wear gaps, the cylinder can be totally devoid of chrome plating, the big end journal can have 1/16 inch slop, and still these things will run. Ive seen engines in this condition. One I remember had rounded head nuts, these had been tightened with a plumbers pipe wrench. I will say ALL engines I have bought were running with sump oil resembling thick tar. .
Samo, your engine will likely refuse to run properly as its too perfect and you are obviously killing it with too much love and affection.
If I believed in reincarnation, Id like to return as your engine.
Re the crankcase pressure, there is always some blowby in these engines, thats what makes the go oil black so quick, so you will have some pressure buildup even in a twin.... but it may be limited.
If you have any doubts about oiling effectiveness, make a clear perspex replacement sump cover.
Steff, just modify/restrict the pipe diameter to deliver just enough oil up top..... the valve guide clearance will hold the level, they dont have seals and are usually fairly loose. ... short rockers cause side thrust on the stems.
I have the injector return dripping onto the exhaust valve rocker, as the slight injector leakage is oil in my case.... and it didnt cost anything other than the few seconds to reorient the pipe.
One other thing I always mean to mention, overheating.
When a Lister gets too hot, it stops without damage. It will begin to lose power, due I think to poor combustion, and will slow to a stop. I have witnessed this a few times with similar engines, so it seems to be a repeatable phenomena.... like im not suggesting its a good thing, but thats what happens.
