Clamping loads can be improved by using a larger size but which can handle higher torque down numbers. It must be noted that higher torque figures can distort and even crack the cylinder block surface and threaded areas of the block. Head studs with equal torque figures cause less distortion. They cause a compressive stress in the lower region below their chamber. When the nut in the upper region is torqued creating a tensile stress in the stud shank, the total tensile stress is less than the applied tensile stress as the applied tensile stress first reduces the compressive stress to zero.
Applied Tensile - Induced Compressive = Reduced Tensile.
Fasteners should always be clean and fitted with an appropriate grease or at least light oil, but never dry. The threads must have as little resistance as possible when the torque is applied.
Surfaces should ideally be surface ground. Accurate milling is however a second option but the leading cut must not vary too much from the trailing cut otherwise the surface will be concave, not flat.
There are many sprays and liquids which can be used on the block and thread surfaces. Some act as a barrier, others are to fill microscopic irregularities, machining marks, low spots or surface scratches.
Gasket Sealers / Compounds:
Our Aluminium and Copper gaskets can be used 'dry' between precision machined head and block surfaces. The Stainless Steel model should be used in conjunction with a quality 'liquid' gasket maker such as Bostik Super Gasket Black Silicon Sealant or equivalent. A thin film should be applied to both head and block surfaces but none to the gasket. Cylinder head gasket sealers should have a temperature range up to at least 300°C.