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Engine Cj2a10973-b

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McG View Drop Down
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    Posted: 05 Apr. 2018 at 11:59pm
https://cnj.craigslist.org/pts/d/early-cj2a-willys-mb-motor/6552018462.html

Not sure what the b means.


Edited by McG - 06 Apr. 2018 at 12:09am
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mbullism View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mbullism Quote  Post ReplyReply Direct Link To This Post Posted: 06 Apr. 2018 at 1:32am
The B means 0.002" oversized cylinder bores from the factory
Those who do not learn from history are doomed to repeat it... Welcome to 1930's Germany
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lowenuf Quote  Post ReplyReply Direct Link To This Post Posted: 07 Apr. 2018 at 5:57pm
Actually, the factory never bored the cylinders. If the serial number was followed by an "A" or a "B", it designated that either the rods or the mains were over sized respectively.

And as an FYI, this engine is currently being held with a down payment, to soon be heading to my place...


Edited by lowenuf - 07 Apr. 2018 at 5:59pm
45 #10012
45 #10033 ACM #47
45 #10163 ACM #188
57 CJ5    Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick



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Post Options Post Options   Thanks (0) Thanks(0)   Quote McG Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr. 2018 at 11:50am
glad it is headed to another from the 2a page.  Might this be a replacement for the v6?  
Now if I could just find one around s/n 60000.......


Edited by McG - 08 Apr. 2018 at 11:52am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mbullism Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr. 2018 at 12:24pm
1948 mechanics manual...(ETA: fwiw, the 1955 MM says 0.010" over)
.
.


Edited by mbullism - 08 Apr. 2018 at 12:35pm
Those who do not learn from history are doomed to repeat it... Welcome to 1930's Germany
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lowenuf Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr. 2018 at 6:03pm
hmmmmmm, never seen that before..... interesting..
45 #10012
45 #10033 ACM #47
45 #10163 ACM #188
57 CJ5    Dauntless V6, T-18 4-speed, D-44 rear/D-30 front, D-20 twin stick



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joe Friday Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr. 2018 at 6:10pm
The factory BOM for MB engines is about 25 pages of 'oddball' parts including very slight oversize pistons, rings, Wrist pins etc. Some were for field fixes, some were for factory salvage blocks.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ol' Unreliable Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr. 2018 at 11:37pm
It seems weird that they would overbore the cylinders by just two thousandths of an inch.  Why not go ten thousandths? 
There's a reason it's called Ol' Unreliable
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mbullism Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr. 2018 at 11:42pm
My guess is at .002 they used a standard piston with over sized rings... the later mechanics manual and service manual both say .01" over, so maybe the moved away from that-

ETA:  also guessing this wasn't anything other than a way to use otherwise out of tolerance parts (?)


Edited by mbullism - 08 Apr. 2018 at 11:55pm
Those who do not learn from history are doomed to repeat it... Welcome to 1930's Germany
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ol' Unreliable Quote  Post ReplyReply Direct Link To This Post Posted: 08 Apr. 2018 at 11:52pm
Apparently Willys pinched their pennies more than I would have expected.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cpt logger Quote  Post ReplyReply Direct Link To This Post Posted: 09 Apr. 2018 at 2:29am
Originally posted by mbullism mbullism wrote:

My guess is at .002 they used a standard piston with over sized rings... the later mechanics manual and service manual both say .01" over, so maybe the moved away from that-

ETA:  also guessing this wasn't anything other than a way to use otherwise out of tolerance parts (?)


Good guess! That is exactly what they did. If you know where to look, you can still find oversized rings for many of the old engines.

Most manufacturers of that era did some of this. The tractor & truck manufacturers used this quite a bit to use up parts that were out of specifications. Aircraft engine manufacturers also used this process to use parts that otherwise would be scrap.

Keep in mind that we did not have the precision casting & machining capabilities that we have now. 

I have heard that the scrap rate was close to 25% of the total manufacturing. While that seem awful high, most of the engineers from that era that I spoke to in the past, confirmed the 25% number. All of them have passed on now.
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