If the compression ratio is increased by machining the cylinder heads, the original tappet rods become too long. As a result, the valves are no longer adjusted correctly and the rocker arm adjusting bolts are not correctly positioned on the valve stem.
The valve geometry can be readjusted correctly using these adjustment plates or shims, they are also recommended when using valve stem caps. Also necessary when assembling the valve adjusting screws with pressure balls or pressure feet (indicated on the related parts tab) to be flush with the fuel channel.
They are mounted under the rocker arm shaft and are available in various thicknesses.
Useful information from Paruzzi magazine and from our YouTube channel :
Du hittar fler tekniska artiklar på sidan Paruzzi Magazine