When I rebuilt my 3.7 Mercruiser, I timed it manually at 4 degrees BTDC. In the water the engine was missing, so I connected a timing light and saw it was several degrees in advance, (2" off the marks on the rotor) I retarded it, and this fixed the missing problem,
but since the distributor has no external way to lock the auto advance mechanism, how do I accurately time it, using a timing light?
but since the distributor has no external way to lock the auto advance mechanism, how do I accurately time it, using a timing light?