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Mopar Engine Production Questions


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I read somewhere that it was about 1938 when Chrysler Corp started up the engine factory in Canada. There they only made the 25” long cylinder head sized block, I learned. This engine could be bored up or down to suit small and larger engines up to the 265 ci. I believe the same block could be used for a smaller 218 ci engine.  Different cranks were used too for various stroke lengths to match cubic displacements. 


I think the 265 is the largest flathead 6 cylinder Mopar car engine. Is that right? I realize they made a bigger straight 8. Was that 8 ever cast/poured in Canada?


Did Chrysler Corp make any 265 engines within the USA? Or were they all poured at the Canadian foundry and  shipped to the USA for cars built there?


Were the shorter 23.5” head size engines destined for USA built cars, all made in the USA?


Pic just for fun. Its a 201 vs a 218 crank. 


Thx. Keith 




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Chrysler in the US made 2 six cylinder engines from the mid 30s to 1960 or thereabouts. There was a Plymouth/Dodge engine, which measured 23 1/4" long at the cylinder head. And a larger 25" long DeSoto/ Chrysler engine.


In 1938 Chrysler Canada got their own engine foundry. It made only one engine, the DeSoto/Chrysler 25" long six cylinder. They rang the changes on bore and stroke to get engines suitable for Plymouth, Dodge, DeSoto and Chrysler. Typically the Plymouth/Dodge engine had a 3 3/8 bore and the DeSoto/Chryslers got a 3 7/16" bore, both using the same block casting.


To get different displacements they used different stroke crankshafts. Each crankshaft got connecting rods of suitable length. Shorter for long stroke, longer for short stroke engines. This way they could use the same pistons.


Typical combinations  3 3/8 X  4 1/16 = 218. 3 3/8 X 4 1/8 = 228. These were used in Plymouth and Dodge. They came as close as they could to the American Plymouth and Dodge engines of 217 and 230 cu in which had different bore and stroke.


3 7/16 X 4 1/4 = 237.  3 7/16 X 4 1/2 = 251. 3 7/16X 4 3/4 = 265.  251 and 265 engines were also used in some Dodge heavy trucks up to 1962 and military Power Wagons up to 1968. Flathead sixes were made as industrial and marine engines till 1972. There was a 241 cu in engine used in prewar Chryslers and DeSotos, don't know the bore and stroke.


I have an industrial 225 cu in engine that uses the 4 1/16 crankshaft with 3 7/16 bore pistons. So different combinations were possible.


So far as I know all straight eight engines were imported.


In 1955 Canada got one V8 engine, the Plymouth/Dodge A engine known as the wide block or Polysphere engine, usually seen as a 318 but also made in 270, 277, 303, 313 and 315 cu in forms.

Edited by Rusty_OToole (see edit history)
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The biggest passenger car flathead six was the 265 version of the DeSoto/ Chrysler block. It required special rod bolts with rounded off heads to clear the cam and block. Used in 1952 - 54 Chrysler Windsor and  52 - 54 Canadian DeSotos. Also used as an industrial marine and Dodge truck power plant. The 251 was much more common.


There were larger six cylinder flatheads of 331 and 413 cu in for heavy trucks but they were a completely different block casting. These monsters weighed over 1000 pounds and often came with dual carbs and dual exhaust.

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18 hours ago, Rusty_OToole said:

There was a 241 cu in engine used in prewar Chryslers and DeSotos, don't know the bore and stroke.

Hi Rusty - The 241 cu in engine was 3 3/8 x 4 I/2 - use in '34 De Soto Airflow, "34 Chrysler CA, CB, CY( Canadian Airflow). "35 De Soto SF, SG(AF)., "35 Chrysler C6, "36 De Soto S1,S2(AF), "36 Chrysler C7, '38 Chrysler C18,  '39 Chrysler C22. My parts book doesn't go beyond "39 so I don't know if it was used beyond '39. More trivia for everyone!

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  • 11 months later...

I have a P6 B coupe made in Windsor Canada body number 486 which would have been a early production run 38 business coupe. It has a 218.06 motor with a 3.375 bore. I have a 25 inch long block. The motor is stamped Truck motor. My question is when did Windsor start producing 218.06 motors? I heard the factory opened in summer 38. If that is true where did Windsor Canada get there motors for there pre 218 factory 38's ? I may be the only one known who has a 38 Windsor business coupe. Since they were sworn to put 218's in there 38's where did they get them from? Canadas 218's had 3.375 bores? Who made my motor? I need to have it bored and the crank ground so I need prats and the correct information. 



1937 Plymouth 2.jpg

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