Supertech Custom Oversize 6mm Stem Valves

These custom Supertech valves are longer than standard, larger diameter and a larger 6mm stem.  The valve sizes are 34.5mm inlet (33.5mm standard) and 29.5mm exhaust (29mm standard) - they feature flat faces to maximise compression ratio, but a slender head profile to minimise weight.  The inlet valve is waisted between the stem and head to maximise airflow around the stem that is open to the port.

They have 6mm stems to increase strength - use these valve guides on inlet and exhaust: https://www.pure-motorsport.co.uk/valve-guides-freccia-1.html

The stems reduce to 5.5mm at the tip so that you can still use standard rockers.

They are longer than the stock valves - inlet is 112.0mm (standard Supertech is 110.05mm long), exhaust is 110mm (standard Supertech is 108.9mm).  The reason they are longer is to allow the rocker position to be reset to a more suitable position when using very high lift cams.  The radius pad on the stock rocker tips off the edge of the valve at valve lifts over 13mm.

Both inlet and exhaust are one piece stainless steel with a black nitrided finish.

They are to be used with very high spec race engines only and need a custom valve spring installation and very careful install to ensure the rocker position is suitable for the cams you are using.

Price includes 8 inlet and 8 exhaust valves.