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raptor06

1GM 10 swop to 2 GM 20

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Hi all. My boat has Yanmar 1 GM 10 with an SD 20 sail drive, i want to replace it with a 2GM 20 , will the SD 20 fit the bell housing for the 2 GM 20 ? are there other alternitives that can utilise the SD 20 .

 

Thanks

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Yes the bell housing is the same bolt pattern. Check the flywheel thickness as the bigger engine may require a spacer due to a thicker heavier flywheel, at least the 3ym later model engines do. 

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I'd be more concerned about the sail drive being able to handle the extra torque.

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I believe the SD20 can be used in Yanmars up to at least 30 hp, likely more (I don't know exactly know how much more offhand), so a lot more torque than a 2GM20 can push out.  The SD20 is used in the J/109 for example.

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The only thing that changes is mountings on the engine bed, as the new engine will no doubt be longer - whether this interferes with any other part of the cabinetry surrounding the front of the engine is something you need to also check. Swapped a 2GM to a 3GM without any problems and for the new engine I ordered it with a shaft drive gearbox and swapped that over to the old 2GM which was still in good condition and sold it for about 60% of the price of the new engine.

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