Oversize Or Undersize Code Component Letter Explanation - Jeep 1987 Wrangler Workshop Manual

GENERAL DESCRIPTION
ENGINE IDENTIFICATION INFORMATION
Oversize or Undersize Components
Some engines may be built with oversize or
undersize components such as:
• Oversize cylinder bores
• Undersize crankshaft main bearing journals
• Undersize connecting rod journals
• Oversize camshaft bearing bores
These engines are identified by a letter code (A)
stamped on a boss (B) between the ignition coil
(C) and distributor (D).
86161A
Oversize
or Undersize
Code Component
Letter Explanation
The letters are decoded as follows:
Code
Letter
Definition
B All cylinder bores
0.010-inch
(0.254 mm) oversize
M
All crankshaft mam bearing
journals
0.010-inch
(0.254mm) undersize
P All connecting rod tearing
journals
0.010-inch
(0.254 mm) undersize
C All camshaft bearing bores
0.010-inch
(0.254 mm) oversize
EXAMPLE: The code letters PM mean that the crankshaft man
bearing journals and connecting rod journals are 0.010-inch
undersize.
86160
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