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Yeoman engine swap

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Gents: This is my first time posting after lurking around for about a year. . . guess its time to get off the pot. I've got a 1970 Yeoman 627 with a damaged 8hp B&S. An earlier owner obviously swapped out the original 7hp (making some nicely done hood modifications in the process). So here is my question. . . What is a better choice, (1) rebuild the existing 8hp, (2) swap in a mid-1980s 8hp B&S from an old Murray, or swap in an early 1990s 12hp B&S from an MTD clone. I can provide engine numbers at some point if that will help, but here is what I can provide at this time. The 8hp that's in it right now ran without oil. Yup, my fault. Embarrassing! It will start, but smokes heavily under any load. Is this worth rebuilding? My knowledge and tools to do this are limited. The 8hp from the Murray was retired by a friend when it failed to start. The Murray sat in a rusting hulk. It would probably be easier for me to get this engine going than the one in the Yeoman. But, would it fit without too many mods? The 12hp runs fine in a working tractor (An MTD, it ain't no Simplicity). Would this fit without too many modifications? Would the 12hp overwhelm the Yeoman's drive train? I would rather work to have a 12hp Yeoman than keep the MTD. The other option is trade all for a working Simplicity similar to the Yeoman I have (any takers?). Thanks, folks, for your time. Jeff in Ithaca

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The 12 hp would probably not fit - the block is larger than the 7 and 8 hp motors. It could likely be made to fit, but require significant modification. Best to stick with the 8 hp. I don't rebuild engines, so I don't have an opinion on that! Tom

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