A quick check would be to use a 3/8 drill motor.. I have the same issues
with EDM lifters.. at rpm I can only get 50psi and it doesnt matter
what RPM.. it runs fine but doent get higher psi.. I have tried both
the standard pump and HV with no change.. I still believe its the
EDM lifters.. this is a SB but I'm sure that BB and SB are the same