I will probably regret raising this, but here goes......
A standard B&L Mk II pump will deliver at maximum 500ml per hour driven at 1000rpm, according to messrs Best and Lloyd.
Whilst this is no big deal with most poppet valve engines of the period, which simply belch the surplus out, it is an issue for the Barr & Stroud engine. One of the best documented and most widely repeated tales is that of Philip Brown and his 1,000cc B&S V twin engined Brough outfit, who seized the engine one day in Dorset whilst trying to cut back the oil to reduce the smoking. What happens in the oil-tight B&S engine is that the excess oil builds up in the sump until the flywheels can get it, at which point commences a smoke screen of battleship proportions. I've had this happen with Ever Onward, which is 500cc B&S powered. The fix is to stop and drain the sump, which solves the problem, but isn't convenient, ever. With the B&L set perilously close to off, it still over-oiled terribly. It now runs a Pilgrim. I don't have delivery rate data for a Pilgrim, but at around 4 drops per minute, it's fine.
Later Best & Lloyd pumps were designed to deliver only 200ml per hour, driven at 1,000rpm, 40% of the earlier pumps, and a tacit acknowledgement that 500cc per hour is too much.
My current project is 500cc B&S powered, and I have a lovely B&L Mk II pump, with tell-tale that I'd like to use, but I need to reduce the pumping rate to around 40%.
Has anybody gone down this path before? What did they do?
thanks,
JFerg