1098 oil pressure light pressure.

[Thomas.hewitt05]

Is there specific pressures that the oil light comes on and off at?

[Bill_qaz]

Depending on switch but normally 3 to 7 psi , I am sure someone will know the factory standard.

[philthehill]

Specified in BMC workshop manual Part No: AKD530L, Part AA, section AA.4 Oil Pressure - the low oil pressure warning light will glow (light up) when the oil pressure falls below 8lb/sq in.

[Bill_qaz]

So my upper guess was close Phil , when I was a mechanic we used to call them "too late lights"

[svenedin]

It is possible to find switches that operate at a higher pressure to give more warning and there are even switches that are variable.

Stephen

[geoberni]

So my upper guess was close Phil , when I was a mechanic we used to call them "too late lights"

I think it's fairly common that the Pressure Switch for the light is going to be a fair bit lower that the pressure at Idle speed.
You don't want it flickering like the Ign Light does when the engine is ticking over, people would be rushing to the garage all the time.....

Idle speed oil pressure is, according to the same part of the WS manual that Phill quoted, Approx 20psi.

[Bill_qaz]

But if it comes on driving its probably too late, much prefer a gauge, that's why
I have oil and temp guages next to each other, you get used to normal needle positions and notice if out of the norm, even when not reading the actual numbers.

20220310_131723.jpg (1.63 MiB) Viewed 175 times

[philthehill]

It is always better to get an early indication of low oil pressure.
I have a 20lb/sq in oil pressure switch fitted to my Minor:- ttps://www.minispares.com/product/Classic/Engi ... %20searchh
a oil pressure gauge and a oil temp gauge.
This is the adjustable oil pressure gauge:-
https://www.minispares.com/product/Clas ... |Back%20to

[les]

Well of course I see the advantage of gauges but despite that I like the simplicity of just a couple of lamps, it’s a Morris Minor after all. For me it’s relaxed motoring, not worrying if I’m running a couple of pounds under pressure. The vehicle I recently sold had me playing that game, although it was more relevant in that.

[Bill_qaz]

An audible alarm wired to the higher pressure is also an option
As you say Phil an early warning of dropping pressure is preferable. Oil temp is particularly advantageous In a competition engine such as yours.
Did once have a rod exit the side of the block on the dyno before the oil pressure dropped, so guauge not infallible
Scary in the days when you shared the dyno room with the engine.