Cylinder head porters need every short cut they can take and maintain the integrity that they so desire.  By installing the inserts, it will save you hours of working with the epoxy that is messy and not as secure as a solid aluminum piece.  These are castings and they are secured with socket head cap screws to make sure they stay where you put them.  Choose the engine you are interested in at right and view the castings.

Click on part number below for more information

For 351 Cleveland 4-V
see INS-351C 4-V

For 429 SCJ
see INS-429SCJ

For Big Block Chevrolet see INS-BBC