I have twin v-6 Mercruisers and VDO tachs and a synch gauge. The tach for the port engine shows 800 rpm less than starboard and the synch also shows starboard is revving higher. I am convinced the engines are actually in sync due to the sound and also they burn the same amount of fuel (each engine has its own tank.) I swapped the tachs and the same port engine shows 800 rpm lower so I have eliminated the tachs as the problem.
Question: What do I look at next? How does the tach get the signal from the engine? Could a bad synch gauge cause one of the tachs to read bad?
I have already made sure the tachs are set for 6 cylinders and by swapping them, the problem didn't follow the tach but stayed with the engines. I am mystified at this point...
Question: What do I look at next? How does the tach get the signal from the engine? Could a bad synch gauge cause one of the tachs to read bad?
I have already made sure the tachs are set for 6 cylinders and by swapping them, the problem didn't follow the tach but stayed with the engines. I am mystified at this point...