I have a 74 cal 3-30 with atomic 4. I purchased it in the last year and have since put on a new bottom and a new martec 2 blade folding prop. I get a considerable amount of vibration when under way. The engine is smooth at an idle and seems run well. It has a 2 to 1 reduction tranny. I can push the boat a little harder than I care to and the vibration subsides. So I only get it at lower cruising speeds. Reverse is fine. I had the opportunity to go out on a old cal 2-27 with an atomic 4 and it was very smooth in all areas of operation. It appears to be something in the shaft or transmission. I had the shaft alignment checked and was told it was ok.
Any suggestions
Any suggestions
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