Hello I have a 1989 v6 johnson looper engine and was wondering what would be concidered good compression: I have 72-75 psi on all cyl but dont have the power I think it should -brought to marina -they striped spark plug hole, didnt tell me till later just said the engine is wore out . starts up good and idles fine it is on 19' statos bass boat with 14.5x26 prop top rpm was 3500 --changed prop to 14.25x17 4 blade and still only could get 4900 rpm any help is appreciated thank you
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