Hardened Valve Seat Fitting & Machining
In cast iron cylinder heads most commonly found in older vehicles, we often find that valve seat recession has taken place mainly on the exhaust valve seats. The major cause of this is due to the introduction of unleaded fuel. (Previously the lead component in the fuel would prevent this recession happening).
We solve this problem by machining the valve seat area to a specific size, then fitting a hardened valve seat insert, which provides greater durability for the extreme temperatures within the cylinder. The insert is then machined to the correct seat angle using a multi-angle seat cutter to give the best possible seal between the valve and the seat.
Even if seat recession hasn’t taken place, as part of our reconditioning process we would always recommend this process be carried out to prevent future issues. Aluminium cylinder heads already come with valve seat inserts fitted from the factory, however some of these can also suffer from recession and other issues over time. In these cases, we remove the original inserts and replace them with hardened inserts which are then machined to the correct specifications.