Yes if the distributor assembly has been turned for any reason or the engine doesn't seem to be running correctly then ignition timing should be checked or adjusted with the earlier EFI Digital Ignition System using MEFI type ECM's.
http://mefiburn.com/ecmrepair.asp
.
EFI / MPI Models
1. Connect timing light to number 1 spark plug wire.
2. Start engine and run at 1300 rpm until it reaches normal operating temperature.
3. Stop engine and connect the scan tool or timing tool to the DLC connector on the EFI/
MPI wiring harness.
4. Start engine, allow rpm to stabilize.
NOTE: 1
MEFI-1 models only, manually adjust remote control throttle lever to get 1200 engine
rpm.
NOTE: 2
MEFI-2 and MEFI-3 models only, ECM will automatically adjust engine rpm to
approximately 1200 rpm when put in the service mode on a scan tool or when using the
timing tool.
5. Check ignition timing. If incorrect, rotate the distributor until timing is correct. Torque
clamping screw to 18 lb-ft (25 Nm).
6. Recheck ignition timing.
7. Disconnect scan tool or timing tool from DLC connector.
8. If required, return remote control throttle lever to idle position and shut off engine.
9. Restart engine, increase rpm to 1300 then return to idle position slowly. Ensure that
engine returns to idle rpm. Readjust throttle cable, if required.
10. Shut engine off.
Mercruiser Engine Timing Procedures | PerfProTech.com
The stickies are typically found at the top of each sub-forum seen before the normal topics like yours is found as an example...The Mercruiser I/O sticky section is titled,
------------ADULTs ONLY -------------------------No Exceptions-----
