Why McFarlane Special Reamers?

Exhaust Valve Guide Cleaning Reamers for Continental and Lycoming Engines

Our special valve guide reamers are sized specifically for cleaning Continental and Lycoming exhaust valve guides. Standard valve guide reamers are designed to perfect the guide hole size when reaming new guides. The standard reamer pilot is sized to fit the small bore of a new unfinished guide to ensure a straight finished bore with stability. When this same type of reamer is used to clean the valve guides, the pilot is smaller than the finished hole. This causes the reamer to wander and misalign in the guide hole. The McFarlane cleaning reamers have a pilot the same size as the valve stem. This properly sized pilot forces the reamer cutter to start straight and follow the correct valve stem path through the guide hole. While using standard reamers to clean valve guides, you have probably noticed some valve guide metal in the reamer flutes afterwards. This metal is cut from the sides of the guide when hard carbon deposits displace the unguided reamer from the original guide hole, or the reamer was not started in alignment with the guide hole. Wavy or gouged guide holes cause premature carbon buildup, poor heat transfer, and early guide hole wear. Prevent damage to your valve guides by using McFarlane Cleaning Reamers!