Oil Cooler Bypass Valve
 

The book says set it to open at 15psi. Has anyone done this?
I've done mine.
What you need:
A compressed air supply.
A regulator with a gauge.
A hose with fittings to connect the regulator to the by pass valve (bpv)
A 1/2" BSP cap.
Tools.

Firstly pull the valve to bits and clean it out (impossible to do the cross bores without un soldering. I didn't do this. I'm gambling.
Make sure the ball is good (not rusted or pitted) (easy to buy a new one at the engineering supply shop)
Check the spring condition is also good.
Put the ball up the hole, followed by the spring, and lastly the adjusting screw. I engaged the screw spigot into the spring and screwed it in with the cap end facing the floor, just to make sure the spring is fitting correctly.
The valve (Thor or Emco) is marked "input" Put you hose on this side, along with the cap.
Wind the regulator up to 15 psi. If the air is flowing through the valve, wind the bpv screw in until it just stops. Now back off the regulator, and wind the pressure back up watching at what pressure it starts to flow through the bpv again.
When I had it right, I put a couple of drops of locktite thread locker on the screw and screwed the cap back on.

I've just done another valve for a friend. Some things to note:
The ball is a 9/16" dia. (just in case you need to buy a new one?)
The book says to set the valve with it sitting in water.
If you hook it up the wrong way around, it will never bypass. (flow coming from the wrong direction holds the ball against its seat)

There are two different mounting brackets for the valve (this goes in conjunction with two different pairs of short pipes (B.P. valve to engine block)
Can anyone identify which carriers had the odd ones? (why the change?- Air cleaner?, Oil filter?)