i converted a mid 80's buick smog pump to make a vacume pump......pulled off the pully,sealed the intake opening,used a ford 6.25 pully,taped the outlet with half inch npt tap,drilled and taped tree eighths npt in the back of the case for suction,ran in line with air/oil seperator to valve cover and ran outlet to catch can.........at idle makes 10 hg.....at wot over 25hg.......so had to run vac. releive valve tee'd in on suction line at pump to limit vac. to 12 hg.........no problems so far........and a lot less than a vac. pump.........