The engine codes give information about the engine and are stamped into the engine block just forward of the lifter valley cover. The code on the passengers side is the legal engine number which should match the vehicle serial number on the body tag - it is a simple serial number and is not detailed on this page. The code on the drivers side is the production code number and is stamped "upside down" when viewed from the front of the engine.

The optional prefix designates a low-compression (9.5:1 instead of the usual 10:1) engine in a larger series cars. Very few engines were built that required a prefix - you should expect this to not be present on your engine.

X4E1001001-
(no prefix)	Normal compression engine as per application (8.0:1, 9.5:1, or 10:1 per application)
X	9.5:1 compression engine used in a 50-60-70-700 series car

The first digit after the optional prefix appears to indicate the series of vehicle the engine was intended for.

X4E1001001-
4	40 series engine (9.5:1 compression for Dynaflow, 8:1 for Syncromesh)
5	50 series engine (10:1 compression, unless X prefix is present)
6	60 series engine (10:1 compression, unless X prefix is present)
7	70 series engine (10:1 compression, unless X prefix is present)
8	700 series engine (10:1 compression, unless X prefix is present)

The remaining digits are the engine production code.

X4E1001001-
E1001001	Engine production code

There is also an optional suffix of a 1/4" long dash ("-") is used to indicate an engine that was originally built at .010" overbore. Very few engines were built that required a suffix - you should expect this to not be present on your engine.

X4E1001001-
(no suffix)	Engine is standard bore
-	Engine is .010" overbore

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Page last updated 01/02/2009 01:51:39 PM