1966 2.5 motor tick

[T time]

I've been helping a buddy get his "new" starcraft going after 6 years of storage. After new points and condenser and a carb re-build we got it running and took it to a lake for a test run. the more we ran it the more a " tick" could be heard in the top of the motor, espcialy in higher RMPs, Any ideas on what it might be. The boat is a 1966 Starcraft holiday with a 110 hp mercruiser 4 cyl. Thanks for any help.

 

[whs109]

Re: 1966 2.5 motor tick

Assuming the rockers/valves were gapped correctly, my guess would be a valve tap due to gumed-up valve guide not allowing the valve to seat all the way (caused by periods of non-use)...worst case, look for mushrooming on valve stem where rocker contacts valve stem. You would have to inspect the intake/exhaust valves for indications of exhaust blow-by to find out which is causing the tap.