You have refaced a valve and recut the valve seat in the head. What is the proper way to compensate for the change in valve spring height?

When a valve is refaced and the valve seat is recut, the distance between the valve spring and the valve can change due to the material being removed from the valve or seat, which can affect compression. To ensure that the valve works properly and maintains the correct spring pressure, adjusting the spring height is necessary.

Adding a shim under the valve spring compensates for the loss of height resulting from the resurfacing. This adjustment keeps the spring preload within the required specifications, ensuring effective valvetrain operation, preventing valve float, and maintaining proper engine performance.

The other options would not appropriately address the changes caused by refacing the valve and recutting the seat. For instance, replacing the valve spring might not be necessary if the original spring is still within specifications, and replacing push rods does not directly address the change in spring height. Removing a shim would further lower the spring height, which could create insufficient preload, leading to inefficient valve operation. Therefore, adding a shim is the most effective and accurate method to correct the spring height after such modifications.