CJ engine information needed (now with photos)

[Carsten]

Hi guys...

One of my colleagues have a 1944 Willys MB with a CJ-3A engine:

Right hand side casting info: 641087-L-W12A N1-CR-N2
Serial number stamp on machined boss above water pump: 3J-124935

There is a thing I find a little strange though. I am normally a MB/GPW guy, so please bear with me here, if I am mistaken. As I understand, the later CJ-3A blocks had the reinforced web in the left hand side rear corner. The CJ-3A information Page http://www.cj3a.info/cj3a/date3a.htmsays:

In 1952 the engine block was changed to one with a larger flange at the rear. The 1965 Service Manual states that this was done at engine serial number (3J)130859.

Now, the engine in question does have the reinforced block, but its engine serial number is lower than the one specified as the first block with the reinforcement. Is there a possible mistake here?

I would say my colleagues engine was produced in 1952, but I will appreciate any information that can narrow it down.

[athawk11]

Even though the published change to the larger rear flange is on engine 3J130859, according to Bob Westerman's book "The Civilian Jeep Model CJ3A, the larger flange actually appears earlier at around 3J124xxx, so your engine is right in the correct timeline for the flange change.

[Bob W]

What numbers and letter are cast in the block on the left side, down low, near the rear?

[Carsten]

Actually, my friend discarded the block in question above, because of cracks in the valve seat area. It will be repaired, but for now he has found a new block, which he is also curious to having dated.

RH side: 641087 L-W11 A NI-CR N2

No serial number stamp on boss above water pump.
Two frost plugs on RH side.
Non-reinforced web on rear LH side.
Number 40558 stamped under lower RH side rear reinforcement web.

Might not be a CJ-3A engine, but any help is appreciated, thanks!

[Bruce W]

Is there anything readable on the brass tag on the RH side, below the distributor hole? This might be a Kaiser/Henry J "Supersonic" block. Which is still the same as the Willys "Go-Devil" used in CJ2-A's and CJ3A's. BW

[Steve Webb]

Didn't some governments put a rebuild tag on the blocks. This is in Europe isn't it?

[Carsten]

Sorry guys,
The picture with the brass tag, is actually of the old engine. He sent me the picture, because it looks exactly like the new one, except for brass tag.
Yes, the engine is in Denmark.

[Sean Collins]

The change from 4 to 2 welch plugs on the passenger side occurred mid-Nov 1950. Material was changed from Nickel-Chromium (NI-CR) to Copper-Chromium (CU-CR) around June-July 1952.

Given the casting date 8-28, too early for 1950, so likely 1951.
 

[Carsten]

Thank you, Sean - that makes good sense!

So we are in the time span of CJ-3A and M38, but is there any way to tell for sure? There is no serial number above the water pump, only the number 40558 underneath. Was the L-134 used in other vehicles at that time?

[Sean Collins]

... Was the L-134 used in other vehicles at that time?

Any/every other 4-cylinder vehicle Willys was making at the time: 3A, M38, 4-63 (Station Wagons, Panel Deliveries), Jeepsters, Pickup trucks, etc., as well as outside commercial users (tractors, generators, welders, compressors, etc.).

If you assume 40558 is a re-stamp of the original number (less vehicle prefix), you could narrow it down by finding a list of production numbers covering those years. I don't have anything beyond '49, but I have seen those list on the net before.
 

[Joe Gopan]

And the Jeep Power Plants in Hobart Welders, Lincoln Welders, John Bean Sprayers, Fire Pumps, etc., will usually have mongrel front engine plates that will not match up on the CJ and other Jeeps and you may not discover that until it is being lowered onto your chassis. Spoils what is usually a fun day.

[Carsten]

Thanks guys...

He only have the block, with no accessories to tell the origin of this engine. It’s hard to tell if 40558 is a restamp of the original engine number. Still weird why it would be removed from its usual place above the water pump. Would engines from welders, generators etc. also have s/n above the water pump?
Anyway, if 40558 sounds plausible for a August 28, 1951 engine, I will have to search for somewhere, but the date seems right at least...

[Sean Collins]

... Still weird why it would be removed from its usual place above the water pump.

Quite common actually. During rebuild, if the block deck needs to be milled flat, it can wipe out the s/n (partially or completely, depending on depth of cut).
 

[Joe Gopan]

Many of the civilian 134 CID Powerplant applications had a data Plate attached w/4 rivets beneath the distributor and on rare occasion a Depot Rebuild Tag would be located there. I believe Henry J. data plate could also be located there.

[Carsten]

Thank you, fellas. This is much appreciated!