Mike Rimu Posted August 31, 2020 Report Share Posted August 31, 2020 Hi there I have my engine in the shop getting re built its a 25 inch block engine # T3834402 cylinder block #666029-1 which I understand is from a 37 MC dodge truck . The engine is in a 1939 Canadian Plymouth P8 sedan and I have no idea of the history of the engine or car. I am looking for parts for it but the thing I have problem is the bore size. From the research I have done the bore size in meant to be 3 3/8 but the bore in the engine is 3 7/16 which means that I would need Desoto or Chrysler pistons not Dodge pistons. I am not sure on the length of the stoke but I'm trying to find that out from the shop. Piston pin is 7/8 and the compression height of the piston is 2 inch (center of the piston to top of the crown) with 2 compression rings and 2 oil. The engine is in New Zealand so it's taken a bit of back and forth with the shop for details. I'm here in the States and wanting to get the right parts before I head home for Christmas. I am just a little confused as a couple of places I rang thought that I would need 3 3/8 size pistons when they looked up the T38 engine number. Anyone come across this engine with a 3 7/16 bore? I have no idea what cc it would be I thought that they were 218. Thanks for all you help out there in mopar land Mike Quote Link to comment Share on other sites More sharing options...
Andydodge Posted September 1, 2020 Report Share Posted September 1, 2020 Mike........please read my reply on the car side..........the engine is a DeSoto/Chrysler based engine that probably originated in Oz via the UK and Canada.........the 3 & 3/3/8th and 3 & 7/16th bore was a common bore used in the 1950's in Oz cars & trucks of all mopar brands as we had the 25" engine ...................just tell the Yanksits a DeSoto/Chrysler engine with the relevant bore & all will be good....................lol..............andyd Quote Link to comment Share on other sites More sharing options...
1949 Wraith Posted September 1, 2020 Report Share Posted September 1, 2020 (edited) The Canadian 2 ton truck in 1942 DD4, DDM4 and FL4 ,FLM4 went to 3 7/16" with 4 1/4" stroke for 236.6 cubic inch, piston pin lists 2 7\8" , length 1 1/8" A rare bird, but maybe a point to start your search, maybe military. If your engine is a Canadian export, a lot of the engine parts are different than the US counterparts I checked my parts list for 1941 Canadian and US long blocks all were 3 3\8" except the C30-C33 being 3 1\4" so probably no luck finding pistons in the States Edited September 1, 2020 by 1949 Wraith addition Quote Link to comment Share on other sites More sharing options...
1949 Wraith Posted September 1, 2020 Report Share Posted September 1, 2020 I found the Chrysler part number for the 1942 Canadian DD4 truck 3-7/16" bore piston and pins: 974072 then ending in 77,80,81 and 83 for .020 to .060 over Quote Link to comment Share on other sites More sharing options...
Dodgefran Posted September 1, 2020 Report Share Posted September 1, 2020 Hi Mike, I have a 1938 Dodge Humpback 1/2 ton with the 25" engine. The engine is at a shop being rebuilt by a guy who has done "more than a few" rebuilds. Sometimes there has been a "rebuild" done and the info hasn't been passed on through during those 80+ years. That block was used (so I've read) as a 218 to a 265, so you have a good range of ci's to look forward to. I even convinced the builder to let me video the teardown so I could put it on Public Access TV. Have fun doing your rebuild. Quote Link to comment Share on other sites More sharing options...
maok Posted September 1, 2020 Report Share Posted September 1, 2020 (edited) This pic is from my '37 MC truck with the same 25" T38 engine manual, Edited September 1, 2020 by maok Quote Link to comment Share on other sites More sharing options...
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