Most people do not stop to realize that the rocker is wider then the valve stem. This makes the rocker only wears at the contact point. If you simply insert a feeler gauge between the valve and rocker the feeler gauge will bridge the wear point and give you a false reading. Unless you know the rockers are not worn you should check for wear and reface each rocker if worn if you want quiet results.

See the USA in your vintage Chevrolet!
My Blog