About C Series Stitching Pins
When considering which stitching pin to choose for a particular repair, you will want to understand the functions of our two types of pins. This page will give you information about the C Series stitching pins. Read about our other stitching pins on the L Series page.
CASTMASTER™ (C Series) stitching pins do not spread the crack! In fact, they do the opposite. This pin with its incredible Spiralhook™ threads creates a drawing pressure that actually pulls the sides of a crack together and permanently locks them together. C Series pins exert pulling pressure.
C Series pins have a complex sealing mechanism. When the shoulder of the pin engages the casting, the pin pulls upward on its hook threads. This creates a radial drawing force on the cast iron, pulling the iron into the threads of the pin. The C Series pin seals over the entire length of its thread.
Cracks that run crosswise on the top of cylinder heads are usually repaired with CASTMASTER™ pins in order to add strength instead of spreading pressure, so the repair will not open when the head is torqued to the block. Cracks that extend from threaded holes, freeze plug holes, pipe plug holes and main bearing holes require C Series pins. Also, cracks that originate from the corner of the cap fit in a main bearing can be repaired with these pins.
Almost all repairs to cylinder heads that are made below the seat angle are made with L Series pins. C Series pins can be used from the bottom of the seat angle outward to the end of the crack. A new seat can be ground or three-angle cut right on C Series or L Series pins. Cracks that extend back into a port are repaired by drilling through both walls. C Series pins will seal on both ends.
So why not just always use C Series pins? The installation process requires that every through drilled hole receive a recessed spotface to assure some of the shoulder of the pin remains below the surface after grinding or machining. The spotfacing is accomplished with a special piloted tool. The reasons not to choose C Series pins for all your repairs are cost, speed and technical requirements. Because of the spotface, installing the pins at steep angles to the surface usually doesn't leave enough material thickness for the threads. (Note: C Series pins can be installed into blind holes without embedding the shoulder into the surface. When the pin hits the bottom of a blind hole, the threads are locked into place.)
For repairs that were impossible just a few short years ago, use C Series pins. The use of locks and CASTMASTER™ pins will produce the strongest repair possible.
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