I'm saying do not start an engine on an engine stand . #1 reason : it's not safe . #2 reason : in order to break in a cam , the engine must be above 2500 rpm for at least 20 minutes and vary speeds and not idle . This will knock over an engine stand . #3 reason: its not safe , especially a 512 Build an engine test stand with an empty 727 case and a torque converter with a ring gear . You can sell the test stand afterwards if you want . remember your life is in your hands .