The photos of the demonstration device that Silva gave me tell the story of metal stitching in a way we can all understand. Descriptions and drawings show differences between the "old way" and the "new way" that results in a better quality repair.) Professional machinists have been doing it for years, but stitching pins and other modern products make it easier and better than ever to do. (Section of the Lock-N-Stitch catalog that tells the history of metal stitching. A catalog that David Silva also gave me has material about the history of metal stitching. I demonstrated how the locking pin worked and Rex said, "Oh, that's just metal stitching you can do that with a plain bolt." He said that he had been stitching metal for years. In addition to showing how a C-Series stitching pin works, it makes a great little conversation piece in the restoration shop. You must pay close attention to the depth of the spotface to make sure there is enough material left for threads.This demonstration device is called a Lock-N-Stitch Castmaster C3 Demonstration View Block. In the combustion chamber this will make the repair more heat-resistant. Whenever possible you should try for approximately 50% of the shoulder to be left below the surface. NOTE: The spotface depth for C Series pins is important. The sealant will lubricate during installation and then cure for retaining strength. You can simply apply LHC623 to both the seat bore and seat and drive the seat in the way you would in a cast iron head. When seat inserts will be replaced after a crack repair it is not necessary to heat the head and freeze the seat prior to installation. Aluminum CASTMASTER® pins should be used in combustion chambers when cracks extend below valve seat inserts and when the inserts will be replaced. Steel CASTMASTER® pins can be used in aluminum castings where heat and corrosion are not a factor. It is often easiest to use L Series pins next to the locks and then continue the repair with C Series pins. In extreme structural repairs, locks should be used in conjunction with CASTMASTER® pins. These changes include a single tap process for through holes, same tap drill size as L6 pins, a hook angle under the shoulder with matching spotface, ability to be used in thinner sections and a large increase in strength and seal. Many improvements, including one of the original design features, have been included in this new version. For sections starting at 0.200" in thickness, use C2F pins and for sections 0.750" to 2" use C3 pins.Ĭ2 was the first CASTMASTER® pin introduced and is now is being replaced with C2F pins. For repairs in thin sections down to 0.100" use C1 pins. You should always choose the largest diameter CASTMASTER® pins that you can. Cracks that originate from the corner of the cap fit in a main bearing can be repaired with C Series pins. Cracks that extend from threaded holes, freeze plug holes, pipe plug holes and main bearing holes require CASTMASTER® pins. C Series pins will seal on both ends.Ĭracks 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 back into a port are repaired by drilling through both walls. A new seat can be ground or three-angle cut right on C Series or L Series pins. C Series pins can be used from the bottom of the seat angle outward to the end of the crack. Because of the spotface, installing the pins at steep angles to the surface usually doesn't leave enough material thickness for the threads.Īlmost all repairs to cylinder heads that are made below the seat angle are made with L Series pins. The reasons not to choose C Series pins for all your repairs are cost, speed and technical requirements. The spotfacing is accomplished with a special piloted tool. So why not just always use CASTMASTER® pins? The installation process requires that every drilled hole receive a recessed spotface to assure some of the shoulder of the pin remains below the surface after grinding or machining. 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. CASTMASTER® (C Series) stitching pins do not spread the crack! In fact they do the opposite.
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