1937 25 inch block re build

[Mike Rimu]

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

 

[Andydodge]

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

[1949 Wraith]

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

[1949 Wraith]

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

[Dodgefran]

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.

[maok]

This pic is from my '37 MC truck with the same 25" T38 engine manual,

 

Edited September 1, 2020 by maok