https://www.nortonownersclub.org/history/dominator
"From engine No. 116372 the con rods had a strategically placed hole drilled in order to squirt oil under pressure onto the cylinder bores. At the same time all models were fitted with a six-start worm drive on the oil pump, supposedly giving double delivery. Along with enlarged oilways, the rockers were now pressure fed from the delivery side of the pump."
My Atlas is an enigma.
I have engine/frame No. 102688, dispatched to Berlina May, 1962. It appeared at my dealer in April, 1963 when I bought it new, and it was titled as a 1963.
This engine has from new, the 6 start oil pump, and the con rod squirt holes.
The NOC record has no indications that this bike was a special build, but having the oil system mods as noted above, would make it seem to be a special build. Further indication of a special build are the Monobloc carburetors which do not have model/configuration numbers stamped on the flanges.
Other possible indications of a special build are the fact that vibration, IMO, is no worse than any 650 Brit twin, the bike beats the snot out of any other Atlas I ever raced, and the engine is less tractable than the first Atlas I owned.
I hope this has not gotten off topic, but I think the occurrence of a 6 start oil pump and squirt holes much earlier than 1966 should be in the record.
Slick