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I am pleased to announce the the new "hard-chrome" rocker shafts to complement the newly introduced, bronze bushed rocker arms, are now in stock and available for immediate delivery.
The shafts are made from 1/4 inch wall, 4130 seamless tubing. Each unit is ground to "near net size", then hard-chrome plated, and finally centerless ground to its final dimension. This provides a ductile shaft (Rc 35) with a very hard outside shell (Rc72) for excellent wear characteristics. In addition, the final ground surface of the shaft has a very smooth and consistent finish, yet will hold oil for excellent lubrication qualities. Each shaft comes with removable end caps which can be removed for inspection and cleaning.
The new design shaft uses an improved oil delivery mechanism whereby oil is delivered directly to the bottom of the shaft, where the highest boundary interface loading takes place during valve actuation. Each rocker is fed by a single orifice, and the orifice has an additional "X" groove to assist in distributing the oil over the width of the internal bore of the rocker arm.
The shaft has been manufactured to standard factory size tolerances to ensure that it can be used with standard steel Fiat rocker arms, Scuderia Topolino bronze bushed, standard rocker arms or Scuderia Topolino, hard anodized, aluminum roller tip rocker arms.
While the full benefit of this shaft will only come to light with more aggressive camshafts, with attendant higher valve lift and spring pressures, even less aggressive engine combinations can benefit from the reduced parasitic friction of this new shaft, particularly if rocker arms with bronze bushes. or roller tipped rocker arms, are employed.