There is no set amount. There was usually three or four shims in the relief valve. Unless there was a fault with the releif valve transfer to the new pump and them test the setting preferable using a flow meter, valve should start to open at 2300psi and be fully open at 2500psi. I seem to remeber that one 0.012" shim was equal to 200psi.
Note the hold relief valve in the valve chest is set to 2500-2650psi
Ash, February 2012
