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Post: 57 Engine Bolt Head Markings

ThumperNZ
Contributor
Posts: 504

Loc: New Plymouth, New Zealand
Reg: 07-08-07

07-13-12 06:59 PM - Post#2247944

During the rebuild of my 2 x 4BC engine, I noticed that the head bolts had a M within a circle, the oil pan bolts had L within a recess, the lower 1/4 UNC bolts had J, the intake bolts had AP within a circle. I have also noticed some TR markings as well, but these may be no associated.
Does anyone know what these mean? Are they manufacturers or a factory code meant to aid the assembly workers.

'57 Model 1037D COMPLETED! (but are they really?

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