52.0.4 Cylinder head
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52.0.4 Cylinder head
The cylinder head casting number for MBs is 639660. Very early 1941 MBs did not use MA heads. The casting number, The Wilson “W” number as well as the Month and Day of casting shown as MM-DD are also cast on the head and are found under the oil filter bracket.
A “C” suffix was added after the first slat grill contract was completed. The “C” may be a revision code or denote the start of dedicated MB production. The casting number will look like “639660C”, and appears on MBs in March/April of 1942. On very rare occasions one may find a LATE head, (JEEP, WILLYS) without a “C” or a mismatched font “C”. This is a mold build room error.
The MB head is smooth, does not have any ribs and the corners and edges are rounded over. Valve tappet clearance and firing order info is on every head. The year of casting is not shown but can be determined by what information is cast on the head.
1941 – All of the above, less “C” after casting number. No “WILLYS or “JEEP”
1942 – All of the above PLUS - “C” after casting number, appears March/April, “WILLYS” cast on head, appears some time after “WILLYS” removed from rear body panel.
1943 – All of the above.
1944 – All of the above PLUS - “JEEP” cast on head, about the same time the word “Jeep” appeared on the frame number tag.
1945 – All of the above.
