What is the length of a mopar flathead 6?

Answer 1

There were two different Mopar flathead sixes, most easily identified by the length of the cylinder head. The smaller one (23" long) included the 218 cu. in. Plymouth and 230 cu. in. Dodge engines. The larger one (25" long) included the 251 and 265 cu. in. versions used in DeSotos and Chryslers. This applies to U.S.-made engines. In Canada, Chrysler Corporation cast only the 25" long block and bored and stroked it in various combinations all the way from 201 to 265 cu. in. The 230 version continued in passenger cars (Dodge and Plymouth) through 1959, when it was replaced by the slant six. The 251 continued in production in Dodge Trucks and military vehicles as late as 1968. In a There were two different Mopar flathead sixes, most easily identified by the length of the cylinder head. The smaller one (23" long) included the 218 cu. in. Plymouth and 230 cu. in. Dodge engines. The larger one (25" long) included the 251 and 265 cu. in. versions used in DeSotos and Chryslers. This applies to U.S.-made engines. In Canada, Chrysler Corporation cast only the 25" long block and bored and stroked it in various combinations all the way from 201 to 265 cu. in. The 230 version continued in passenger cars (Dodge and Plymouth) through 1959, when it was replaced by the slant six. The 251 continued in production in Dodge trucks and military vehicles as late as 1968. In a more exotic vein, there were some huge flathead sixes made for big Dodge trucks in the '40s and '50s as well. Some of them were as large as 431 cubic inches! But all those are rare as the proverbial hen's teeth. By far the most common Mopar flathead one finds is the 230. Note that the manifolds are not interchangeable between the two sizes of block. The Mopar flatheads were known for g There were two different Mopar flathead sixes, most easily identified by the length of the cylinder head. The smaller one (23" long) included the 218 cu. in. Plymouth and 230 cu. in. Dodge engines. The larger one (25" long) included the 251 and 265 cu. in. versions used in DeSotos and Chryslers. This applies to U.S.-made engines. In Canada, Chrysler Corporation cast only the 25" long block and bored and stroked it in various combinations all the way from 201 to 265 cu. in. The 230 version continued in passenger cars (Dodge and Plymouth) through 1959, when it was replaced by the slant six. The 251 continued in production in Dodge trucks and military vehicles as late as 1968. In a more exotic vein, there were some huge flathead sixes made for big Dodge trucks in the '40s and '50s as well. Some of them were as large as 431 cubic inches! But all those are rare as the proverbial hen's teeth. By far the most common Mopar flathead one finds is the 230. Note that the manifolds are not interchangeable between the two sizes of block. The Mopar flatheads were known for great durability (they had hardened exhaust valve seats, among other advanced features), smoothness, and pretty good efficiency for the day. Although the design was simple, the engineering was very carefully carried out (the original design was laid down by the famous trio of Zeder, Breer, and Skelton, who designed all the early Chyrsler products, including the revolutionary 1934 Chrysler Airflow), and the materials were good. The basic form was set by 1935, when the block was modified to provide full-length water jackets around the cylinders. --Michael Sawdey, msawdey@aol.com

Aurora, Illinois, USA