If All Else Fails.
O.K. This is a Dumb Guy Solution from When Datsun 240Ks were New.
Used to Install C.D. Ignitions back in the Day and Always had Problems with the 240Ks.
Too Much Fuel Pressure to be Able to Lean Them Down
It was weird, Oil Pressure around 15 P.S.I. at Idle, Fuel Pressure about 15 P.S.I. at Idle.
O.K. what we did was to Cut into the Fuel Line Either side of the Fuel Pump & Recirculate the Fuel.
This Relieved the Pressure on the Carby.
I'm sure in this Day & Age there Must be a Smarter Solution But it Solved our Problem Back Then.
Regards Tony.M