i have a 98 7.4 mfi 310 hp and i need to know what the timing should be set at and is there anything you need to disconnect like when you set the timing in the trucks thanks Ed

Usually there is a tag from Mercury on the valve cover with the timing setting on it. I know my 7.4 is 8 degrees BTDC but not sure on the MPI.

You short the A and B terminals on the diagnostic connector, this puts it in base timing mode. Then most engines get set at 8 degrees BTDC. My balancers actually have an 8 degree line highlighted.

Start the engine, adjust the throttle to 1400 RPM. Jumper terminals A and B on the Data Link Connector (DLC) to place the engine in Base Timing Mode. Then set the timing with a timing light.