Brian wrote me asking if I knew what type of engine this was.  He pulled it out of a old WWII Jeep and didn’t recognize it.  He wrote that the Head cast was #634816 and the block casting#630282. In particular, he noted the exposed cylinder tubes.

I told him I didn’t know what it was, and confessed that I had never worked with any MB/GPW motors, but I would do my best to figure it out (I do enjoy a good internet hunt). After searching through various images I could see it was similar to a MB and GPW motor, but was also different.

For example, you can see examples of GPW heads here at Dino’s site and though it looks similar, it’s missing various features.  Here is an example of MB block.  In fact, if you go here, you can review all kinds of WWII engines.

After trying various keyword images searches, I tried typing in the casting numbers and that is when I discovered that the head was a pre war head from a Willys Model 37. So, then I looked at prewar Willys.  On this page http://clubs.hemmings.com/clubsites/wocv/willywilly/willywilly.htm on the fourth pic down, you can just make out, just below the distributor, similar indentations on a 1938 Willys.  Here is a better look at a prewar block.