Usage:
3400 and 3400B Families Of Engines
On engines in the 3400 and 3400B Families, some head bolt holes in the cylinder block may have worn or damaged threads. Here is a salvage procedure that can be used to replace the threads and reuse the block.
Remember, this procedure is limited to the repair of only two bolt holes in each block head face (or bank), and to only one hole per cylinder bolt pattern (six holes per pattern). Various Heli-Coil® installation tools are used. Do NOT use the oversize Heli-Coil Twinsert Inserts to repair these holes.
NOTE: This procedure on 3400 and 3400B Marine Engines may be subject to Marine Society approval.
The first three machining steps, counterboring, drilling, and retapping in that order, are shown in the illustration. Next, check the threads with Gauge No. 1441-12 to a depth of 2.62". Then, install No. 1191-12 CN by 1.5" Heli-Coil Insert to a depth of 1.105" to 1.111" deep.
Drilling and tapping prior to installation of the Heli-Coil insert in the head bolt hole.
The special tap and the thread gauge are included in the Heli-Coil insert kit.