after 5 years of trying I recently acquired this WW2 stationary power plant , absolutely complete and I would think brand new , previous owner got it at an auction in the late 50s early 60s and never used it apparently there was plenty of them around post war but I`ve never come across one before . Just wondering the HP for it , it`s an 81T ,from my research I believe it is 239ci as per the Mercury of the time . Cheers .
81T is rated at 85 HP. Should be 221 cu. in. 81 designates first year of application to be 1938. First Merc was 1939 @ 239 cu. in. DD
Mercury motors from 1939-1948 were 100 HP. The early Merc motors 39-42 were in the larger work trucks also. The T was for the trucks. I believe it was the 1 1/2 ton and larger trucks. The way to know if it is a Merc is took look at the center water jackets under the head. You will have trapezoid jackets top and bottom with a round one in the middle. There are no markings on the outside of the block to tell. The Ford and Mercury look the same on the exterior.
Despite the "1" in the part number prefix, 81T heads were used on 99 engines as well as the 221 truck/industrial engines. So that means nothing, and it means even less since it is an easily swapped external part! Also, wartime Canadian flatheads were produced in both the '39 and the '41-2 versions... Yours looks to have at least the oil filler breather from the PCV equipped setup, possibly making it the late sort. Early, '39-40, would have 2 bulges on each side of block leading to soft plugs in the pan rail and a flat top where intake goes. Some 239's had 99 stamped at right front of top. '41 up type had a sort of raised pad area for the intake manifold, lat block sides, possibly extra holes/fittings for oil cooler or full flow setup. Yours seems to have '42 type ignition and will likely prove to be a 29 or 21 type.
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