Check your oil level and oil pressure. If they are hydraulic lifters, the
will collapse with low pressure or poor oil flow. Check the filter also.
Bill

"B. Alexander" wrote in message
...
Hi,
I would like to know the proper way to adjust the intake/exhaust valves on
my Mercruiser Alpha One 3.0L inboard, they are making a loud clacking
sound
when the engine is at full speed.
Thanks in advance.