This tooling has been used in rocker arm thread repair
where the threads must start a few millimeters deep below a "Slot".
The core drill countersink combination will have to set by hand.
We use this special 4 flute core drill because it makes drilling
thru a slot easy. Using a traditional 2 flute is difficult because the drill
it wants to hang on the slot and break.
INSTRUCTIONS CLICK HERE:
Rocker arm support can be GM style 3100 and 3400 models along with Buick and others.
Picture below is of the Olds Alero V6 rocker arm bolt and support.
The insert must be below the notched portion of the support.
so our standard
repair kit for the M8x1.25 will not work.
The special 4 flute core drill included will cut thru the notched
area without
difficultly. A standard 2 flute drill would hang on the sides.
Link back to standard size page
http://www.timesert.com/html/misc.html#1812core