Gordon, Thanks for your comments. As it turns out we did put the new injectors back in and it runs great. We did check the timing a little bit differently and found it to be right on. We simply bled the system and connected the injectors with injectors out of their "holes". We turned the engine slowly (counter clockwise) and the injectors "popped" with marks at tdc (or slightly advanced of it). That was good enough for us. The reason we wanted to check is that we bought the boat used with no record of engine hours. The owners manual indicates the timing should be checked every 500 hours. The only thing is the timing marks on flywheel (1 and 2) don't correspond with the cylinder that is actually firing. The Yanmar service manual says that matters concerning injector timing do not always correspond with the cylinder numbering (re: cylinder #1 being on flywheel side and #2 being on timing gear case side of engine)so we did not worry about that. Again, Thanks. Doug