RE: 1939 - 1942 Mercury & Ford truck blocks Does anyone know if the 221 '39-'42 flathead is the same block as the '39-'42 239 block? I know if you take the steel sleeves out of the 221 you can hone it to a 239, so is the 221 really a 239 with steel sleeves? Are crank jourals the same? cylinder walls the same? Thanks!
They are not the same. The cylinder decks have different center deck water port and the 239 engines have much thicker cylinder walls. There are differences between 39 thru early 41 blocks and later 41 thru wartime 29A type blocks too. Namely the pan rail casting sand removal ports that have little soft plugs in them. These create a bulged effect on the 39 thru early 41 engines in four places. The later engines don't have them. The earlier blocks to 41 have a flat intake deck and the later ones thru 29A have a raised appearance where the intake is installed that follows the shape of the intake.
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