Editing Vortec L31 cylinder head (section)
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==Rocker arm studs== Production L31 Vortec heads come with pressed in 3/8" studs. For high performance and/or solid lifter applications, screw in studs are highly recommended. The pressed studs can be pinned, but this is a stop-gap measure that should be done only in cases where the spring pressures/engine RPM/lobe intensity will not be excessive and/or the budget is limited. Otherwise use ARP screw in studs or their equivalent. If not using guide plates, non shouldered straight studs like Pioneer p/n 850001 screw in studs can be used. This type of stud is tightened by "double nutting" instead of tightening it by a hex. ===Stud boss modification=== If a hex stud is to be used, the stud boss will need to be shortened. The amount to remove varies depending on the stud being used; not all studs use the same radius from the hex to the stud. If a guide plate is used, add the thickness of the guide plate, the hex, and the stud radius together to reach the amount that has to be removed. This can be anywhere from about 0.320" to 0.375". The main consideration is that the rocker arm trunnion (if a roller rocker) or the rocker slot/pivot ball (if stamped steel rocker) doesn't bottom out on the stud radius. Check with the manufacturer for these dimensions if need be, otherwise the stud and guide plate can be measured with a caliper. ===Guide plates=== Guide plates can also be installed at this time if desired. Consider Isky adjustable guide plates. Using guide plates will require the stud bosses to be machined shorter to compensate for the thickness of the plates and the hex on the stud. While home builders have successfully installed screw in studs without specialized equipment, unless the builder is well versed in doing this type of work, i.e. drilling straight, correctly located holes and tapping them, this is better left to a professional machinist/machine shop. At the least, a fixture to guide the drill bit and tap should be used. <br> {{Note1}}If using guide plates, non self aligning rockers need to be used. If guide plates are not used, self aligning rockers MUST be used. {{Note1}}Hardened pushrods must be used with guide plates to prevent excessive wear.
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