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Plotting Engine Numbers


 

1954 F-headThis engine, with engine number 4J51093 stamped on the block above the water pump, is almost certainly the original engine for Chase Myles' 1954 CJ-3B in Phoenix. According to the Surviving CJ-3B Jeeps List, that engine number corresponds to the Jeep's serial number 454GB219746 in a way very similar to the numbers of many other 1954 Jeeps in the Database.

Keith Buckley has done a regression, which is a systematic statistical analysis, of the numbers for all the 1953 Jeeps in the Database. It indicates what engine stampings can be considered original for a given 1953 serial number (VIN), with 95% confidence. This has been plotted on the graph seen below, which allows quick reference.

A similar graph further down this page plots engine and serial numbers for 1963-66 CJ-3Bs from the Database, along with data from plant records.
 

1953 Engine Number/VIN Regression

Keith says, "I got to playing with the owner data and analyzing it. I eliminated known outliers, and anything with a suffix indicating it wasan overbore or non-standard bearing. Those "B" suffix engines are always much higher numbers because they were inserted in batches of 100.

"The engine number was commonly 2000-3000 higher than VIN. This makes it easy to determine if the engine in a 3B is suspect."

1953 engine numbers

Barely noticeable in the 1953 plot is a bit of a change in the curve around the middle of the 1953 model year. For the first half, the engine numbers seem to be generally only a couple of hundred higher than the VIN. Then around VIN 21000 there are suddenly several which have engine nos. slightly lower than the VIN, as if the plant was using up old stock. From there on, the engine numbers rise faster, as if the 4J engines are also being put into other models, so that by the end of the year a CJ-3B probably had an engine number more than 3000 higher. Maybe this was the result of the 2,267 stripped chassis 3B's which perhaps went into production in the latter part of the year?

The 1953 Numbers Used

The following are the Jeeps plotted from the Database as of mid-2003. Not included here is the VIN prefix of 453GB2, or the engine number prefix of 4J.

VIN Engine No. 95% Confidence Lowest 95% Confidence Highest Predicted Engine No. Difference Actual to Predicted
10691 10858 9689 10950 10319 539
11268 11377 10323 11604 10963 414
11644 11845 10736 12031 11383 462
11619 11695 10709 12003 11355 340
11914 12235 11033 12338 11685 550
12172 12380 11317 12630 11973 407
12305 11856 11463 12781 12122 -266
13887 14173 13202 14577 13889 284
14024 14340 13353 14732 14042 298
14464 14693 13836 15231 14533 160
14465 14687 13837 15233 14534 153
14870 15035 14283 15692 14987 48
15005 15217 14431 15845 15138 79
16936 17078 16554 18037 17295 -217
17343 17275 17001 18499 17749 -474
19783 20391 19683 21268 20475 -84
21059 21050 21086 22716 21900 -850
21070 20634 21098 22728 21912 -1278
21480 21562 21549 23194 22370 -808
22127 22359 22260 23928 23093 -734
24825 25440 25226 26990 26107 -667
25560 26895 26034 27824 26928 -33
25873 26358 26378 28179 27277 -919
26286 27509 26832 28648 27738 -229
27636 28923 28316 30180 29246 -323
27777 29124 28471 30340 29404 -280
27940 29507 28650 30525 29586 -79
29292 31180 30136 32059 31096 84
29888 32217 30791 32736 31762 455
30929 33169 31936 33917 32925 244
31566 34067 32636 34640 33636 431
31723 34112 32808 34818 33812 300
33232 35455 34467 36531 35497 -42
33236 35872 34471 36535 35502 370
33900 36925 35201 37289 36243 682
33938 36942 35243 37332 36286 656
34687 37231 36066 38182 37122 109
36522 38915 38084 40264 39172 -257
36620 39697 38191 40376 39282 415
37408 40288 39058 41270 40162 126

 

1963-66 Engine Number/VIN Plot

1960s engine numbers

Factory engine number documents found by Keith, show some changes that are harder to spot from the limited number of owner records in the Database, but when you see the two together they correspond pretty closely.


Thanks to Keith Buckley for putting this together. -- Derek Redmond

Return to CJ-3B Serial Numbers and Production Figures.

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Last updated 11 October 2003 by Derek Redmond redmond@cj3b.info
http://cj3b.info/SerialNos/EngineNosPlot.html
All content not credited and previously copyright, is copyright Derek Redmond