Let me type this out:
Cracks in the cylinder head or block can often be repaired by either brazing, welding, or pinning.
Sometimes solder can be used on water jacket cracks.
The use of threaded pins is quite popular because no heat is required.. no chance of warpage.
If the pins are to be effective, they must reach slightly past the ends of the crack.
Use threaded taper pins designed for crack repair.
Start by drilling and tapping a hole that centers on the crack line, just beyond the end of the crack.
Thread the correct size pin.. pin may be coated with special heatproof sealant if desired into the hole.
When tight, notch the pin, about 1/8 inch above the casting.
Use a sharp chisel. Twist off the excess.
In some cases a hacksaw may be used to cut the pin.
Drill and tap for the next pin so the hole just cuts through the threads of the first pin.
Installl plug and twist off excess.
Repeat this process until the full length of the crack is pinned.
Each pin must cut part way into the preceding pin.
If steel pins are used they should be lightly peened.
Grind pins nearly flush with work and finish with a clean sharp file.
If the area cannot be filed, grind flush.
When a crack passes over an edge such as across head and down into combustion chamber insert pins in the order shown in figure 8-54.
Insert pins in the order shown. Pin #6 will lock pin #5 in place in case pin #7 does not properly overlap.
pages 141-142 Auto service and repair Martin Stockel @ 1984