Willys MA Cylinder Head?

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tombonMB44
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Willys MA Cylinder Head?

Post by tombonMB44 » Wed Oct 04, 2017 1:38 pm

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Hi All,
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I have just brought home a 1942 Willys MB which has a great history. It was used by the Australian forces in the Pacific theatre and then sold to the father of the guy I bought it from at the end of its war service in 1946. It then worked on a farm until 1975 when it was parked up until I came across it. It has had a lot of mods done to the tub but the chassis and all else is very original and unmolested. My reason for coming on here today is that the engine is a bit of an enigma to me and any wisdom and/or assistance anyone of you can provide would be greatly appreciated. As you can see from the attached pics the Jeep is a December 1942 Willys MB. It has an engine block which appears to be a 1939 and a cylinder head which, I believe could be a Willys MA head? The vendor of the Jeep states that it is the original engine it had in when his dad purchased it and I have to say that it does look very much like it is the engine that belongs to the jeep if that makes sense. On that basis it would have had this engine during its military life either all the way through or at some point during that time. Can anyone confirm if 1939 Willys engines were used in Wartime Jeeps? Is the Head a Willys MA head? Any guidance, help, advice and/or information would be greatly appreciated.

Thanks in advance.
Tom


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Re: Willys MA Cylinder Head?

Post by rjbeamer » Wed Oct 04, 2017 3:11 pm

First off I have never heard of any war time Willys using the 1939 engines from the factory. The 1939 engines used a head that looks like this one that has a 2 bolt thermostat housing. Why do you think that this is an MA head if I might ask?

You show a picture of the distributor Tag but the date code is dirty and unreadable. What is the letter just before the #2 on the tag.

Roger

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Re: Willys MA Cylinder Head?

Post by tombonMB44 » Thu Oct 05, 2017 12:57 am

Hi Roger,

Thanks for the reply. The stamping one the head 637014 W2 led me to think it may be an MA head. As I said, feel free to correct me if I am wrong but doing some research on web led me down that path.

I will get the date off the Distributor and reply shortly.

Thanks.

Tom

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Re: Willys MA Cylinder Head?

Post by tombonMB44 » Thu Oct 05, 2017 1:14 am

Hi Roger,

The letter next to the #2 on the distributor tag is R

So the full reference reads: GS4007 12 R

I am really just curious as to whether this engine was in a supply of spares and was put in to the Jeep during the War or whether it would never have been an engine used in wartime Jeeps. If the head is original to the engine then the head is not from an MA but from what I read from other posts, Willys MA Jeeps had the cylinder head ref: 637014 W2. If all MA's had this single stamping on their heads and these heads were not used with that stamping on any other vehicle, I kind of deduced that this would be a Willys MA head. Happy to be corrected and educated as that is what we are here for ultimately.

Thanks again.

Tom

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Re: Willys MA Cylinder Head?

Post by rjbeamer » Thu Oct 05, 2017 6:41 am

On the Distributor 12R equates to Dec. 1938. R is the code that Autolite used for 1938. That would be in line for use in an early 1939 engine application.
My feelings are that this is a 1939 Willys car engine that was installed in the Jeep after it left the military. I think that the head is original to the engine. The head with the exception of a possible date code is the same as the head that Willys used on the MA. IMO

Roger

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Re: Willys MA Cylinder Head?

Post by W. Winget » Thu Oct 05, 2017 9:46 am

I think from memory you will also find the 39 and 41 (they skipped 40) had Babbitt bearings with Bering shells used in the 42 blocks and military MB engines. You can in theory go back into the 41 and put inserts in, by changing the rods (maybe the mains as well, I cant recall the posting) but the 39 is pre-war.

A small tidbit I learned was they tossed in a 39 series at the Camp Holibird test grounds when they blew the MA engine during initial tests after about 1200 miles (again from memory looking it up in May for Aberdeen). You want to dig a little by looking at my old posts, we took a 41 up to Aberdeen MD for sale and the experts here filed us in on what was what.
Nice jeep either way....as someone said, it's better than using a generator or CJ engine.
V/R W Winget
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Re: Willys MA Cylinder Head?

Post by Fred Coldwell » Fri Oct 06, 2017 5:58 am

Tom;

The Willys cylinder head with cast-in part number 637014 is original to the Willys engine used in its model 39 motor vehicles, so the head on your model 39 engine matches the block, as does the distributor per Roger's decoding remarks. That same cylinder head was later used in MA jeeps. But without knowing the actual casting date on your 637014 cylinder head, which is too blurry to read in your photo, it is unlikely that the casting date falls within the month and day range of casting dates for the 637014 cylinder heads later used on MA jeeps.

The U.S. Army did not stock pre-war model 39 engines to be used as replacement engines in MB jeeps. Instead, the Army ordered and warehoused additional MB engines to use as replacements in MB jeeps. I agree with Roger that the model 39 engine found in your MB mostly likely was installed after your jeep was surplussed from the Army following WW II.
Happy Jeep Trails,

Fred Coldwell
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1945 CJ2-26 - X50
1944 Dodge T233 CC
1945 Dodge T233 Utility
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Re: Willys MA Cylinder Head?

Post by tombonMB44 » Mon Oct 09, 2017 3:51 am

Thank you all for your replies and information. As always a great source of information and greatly appreciated.

Many thanks.

Tom

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Re: Willys MA Cylinder Head?

Post by W. Winget » Tue Oct 10, 2017 8:54 am

My bet:
Someone in 42-45 swapped their tired 39 Willys Car engine into a jeep and drove off in a fresh car...
:shock:
Or maybe there was a Willys Car around when they didn't have a lot of surplussed MB engines in Australia in the beginning and someone blew the engine and didn't want to get caught for for having blown it. :lol:
V/R W. Winget
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