Hi

I saw a Special today that looked as if it had once been used for trialing. When up to temperature, the engine ran at an oil pressure of at least 20psi. (No blocked jet!)

It had what looked like a three bearing crank case (with rib half way along) but also a (presumably skimmed?) low compression head with 18mm plugs. The sump was aluminium.

I wondered what sort of lubrication system might give rise to 20psi+ in a Seven engine?

Regards

Colin

Colin,
The three bearing engine when introduced had a reduced size oil jets to try and build a decent oil pressure for the centre main. Further ways of doing this are an offset bored oil pump to displace more oil and restricted feeds to the camshaft bearings to force yet more oil to the centre main - and build more pressure.

Another thing is the deep sump - oil takes ages to get fully warmed up in these and this keeps up the pressure though sluggish oil isn't always good for the bearings. Was it warmed up when you saw it running?

Dave