Achieving perfect valve train geometry is the hallmark of a professional air-cooled engine build. When you are building a high-performance VW engine, whether it is a street-pounding 1776cc or a race-ready 2332cc, the relationship between your camshaft, pushrods, and rocker arms is absolutely critical. If your geometry is off, you risk excessive valve guide wear, lost valve lift, and potential catastrophic engine failure due to side-loading the valve stems. This EMPI Rocker Stand Shim Kit provides the precision adjustment needed to lift the rocker stands off the cylinder head mounting bosses, allowing you to re-center the rocker arm tip on the valve stem. By using these shims, you ensure that the rocker arm ''''scrub'''' or ''''swipe'''' is minimized and centered at half-lift, which maximizes the efficiency of your cam profile and protects your investment in high-quality cylinder heads and valvetrain components.
This comprehensive kit is designed for the serious engine builder who demands versatility and accuracy during the assembly phase. Including a total of twelve precision-stamped steel shims, this set offers three distinct thicknesses.015 inch, .030 inch, and .060 inchwith four pieces of each size included to cover both cylinder heads. This variety allows for the fine-tuning that simply isn''t possible with a single-size approach, especially when dealing with heads that have been milled for higher compression or when utilizing aftermarket high-lift camshafts. These shims feature a square footprint that matches the standard VW rocker stand base perfectly, ensuring a stable and secure mounting surface that won''t shift under the high-stress environment of a high-revving engine. Don''t leave your valve train to chance; use these shims to dial in the mechanical harmony your Type 1, 2, or 3 engine deserves.
This kit is designed for use with all air-cooled Volkswagen Type 1 based engines utilizing standard-style rocker stands. This includes:
The following technical specifications ensure you have the right measurements for your engine blueprinting process:
To determine the correct shim thickness, you must check your rocker arm position at exactly half-lift. Rotate the engine until the valve is halfway through its total travel. At this point, the adjusting screw (or the rocker arm tip) should be in a perfectly straight line with the valve stem. If the rocker arm is pointing downward toward the head, you need to add shims from this kit to raise the stand. If it is pointing too far up, you may need to machine the stands or the head bosses. Perfect geometry ensures the rocker arm tip stays centered on the valve stem throughout the entire cycle, preventing the tip from ''''walking'''' off the edge of the valve.
Adding shims under your rocker stands will effectively change the distance between the rocker arm and the lifter. This means that once you have determined the correct shim thickness for your geometry, your stock pushrods will likely be the wrong length. We always recommend using an adjustable checking pushrod to find the new required length, and then ordering a set of custom-length chromoly pushrods. This ''''shimming and measuring'''' process is the only way to ensure your valve train is stable at high RPMs and that you aren''t losing lift due to poor mechanical leverage.
When you raise the rocker stands using the .060 inch shims (or a combination thereof), the entire rocker assembly sits higher within the cylinder head. Always do a dry fit with your valve covers and gaskets before final assembly. On some performance heads or with high-ratio rockers, the increased height can cause the rocker arms to strike the inside of the valve cover. If you encounter interference, you may need to use extra-thick valve cover gaskets or high-clearance bolt-on valve covers to provide the necessary room for the moving parts. Never assume there is enough room; always check for clearance by rotating the engine by hand for two full cycles.