I have a 1985 Searay Monoco (cuddy cabin) with a Mercruiser 1984 228R (GM 5.0 litre 305 V-8 w/Rochester 4bb carb). The original engine suffered a cracked block and had to come out. I purchased and installed a rebuilt long block (block and cylinder heads). I am almost positive I set the timing right because the engine runs smoothly, until I try to bring it down to idle. As pull back on the throttle and get the RPM's down under 900, the engine bogs down, sputters and dies. I have since had the carb rebuilt, installed new plugs, wires, distributor cap and rotor, and new ignition coil. I have had the alternator tested. There is new fuel in the tank (50 Gal.). I have tried incrimental turns of the distributor to fine tune the timing. The timing should be 8 degress TDC for this engine, but I assume that sould be at idle, which I cannot do. The timing mark is off significantly to the left (facing the stern of the boat) when it runs it's smoothest. I assume this is because of the increased RPM's and that it would come in line as the engine slows. The only other thought I had is that I didn't set the lash correctly. Could this be the issue even though it runs well at higher RPM's? Any other thoughts? Please Help!
