Hi Phil,
There is no adjustment on the SD1 V8 lifters. The only engines that had adjustable rockers were the 'so-called' homologation engines fitted to the Twin Throttle Plenum Vitesses and they were welded up on the road cars.
Hi Wallace,
You're almost right, the oil pressure switch cuts out the fuel pump if oil pressure is low when the engine is running (the pump is powered during cranking).
As has been mentioned above, a 500 cfm carb is way over the top for a 3.5 and I would agree that overfuelling sounds like the problem here.
I had an '85 Vitesse for 18 years, great engine and huge fun to drive.
I also had the twin Plenum Vitesse - and yes the oil pressure switch failed - oil leaked through it. 5 min job to change it. Other than that totally reliable. I also have a Classic Range Rover with the V8 and used to have a JE motors V8 110 . Oh and a Westfield Seight I used to borrow off a mate. My favourite engine!