Early Hemi Tech West Coast Willys Club

Jim Jordan of El Cajon, California has kindly offered a short review on the differences between Industrial and Marine Early Hemis versus Passenger Car Hemis when you are looking for a suitable motor for your Willys or any other hot rod. Many thanks to Jim for his detailed response from a recent West Coast Willys Club Willys Guys E-Mail list post.............

Sent: Saturday, July 11, 2009 10:31 PM
To: willysguys@westcoastwillysclub.com
Subject: [willysguys@westcoastwillysclub.com] Industial HEMI

I will try to give you a bit of what I know from my experiences. Before looking at anything, or buying or not buying it, have the owner give you the serial number which is located on the top block surface at the very front of the block.  There is a ½” wide pad just ahead of the valley cover with a stamped serial number.  Attached is a chart of the prefix of serial numbers identifying Chrysler motors and the model the motor was installed in.  All of these are passenger car motors. If, within the first three or four digits it has an “M” or “I” …it is a Marine or Industrial motor.  “Poly” motors had the same passenger block but with different pistons, cam, heads, rockers and valve covers.

 The 50s and 60s was still a time when it was common to order a car just the way you wanted it and the factory would sell or build just what you wanted.  This was particularly true for Industrial and Marine equipment. An industrial or marine motor was always found being use for that application. It would be a separate thesis to discuss why the many differences but the primary reason was that I and M motors were designed to, and needed to, run unendingly at lower RPM without failures. There were rare instances where passenger motors were used in an industrial or marine application.  One application could be in back-up generators so that parts were available locally at dealers.  So, just because the application was industrial, the motor could be a passenger motor. The odds are not good, but it could be. The serial number will most always tell you. Once in a great while a motor will show up with no serial number.  The guess is that it was a crate motor of some sort so one has to then study the heads and front of the block.

 Essentially, I and M motors are parts donors for their rods, rocker assemblies and valve covers. The I and M cranks are different in the snouts, the blocks are different in the bolt and cooling patterns on the front of the block, the cams are different in lift, duration and their snouts.  Also, many marine motors were used where there were “twin motors” … and one was counter-rotating.  The heads will interchange but are different in cooling, etc.

 What one really wants is a 1955 – 58 passenger motor (having the non-extended block and having water ports in the ends of the heads) and a corresponding passenger serial ID.  Then, all the after-market aluminum and hot rod stuff will bolt onto it.

 Hope this is of some help

 JJJ

 

 


From:
Sent: Saturday, July 11, 2009 10:31 PM
To: willysguys@westcoastwillysclub.com
Subject: [willysguys@westcoastwillysclub.com] Industial HEMI

 Does anyone know what some of the differences might be between the industrial / truck Hemi's compared to a passenger car Hemi ?