Why McFarlane Special Reamers?
McFarlane offers special reamers in the necessary sizes to clean your Continental and Lycoming engine exhaust valves. Standard reamers manufactured for aircraft valve guides 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 insure stability and a straight finished bore. 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 while it is being started and turned in the guide hole.
The patented 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. Finally, a tool that is designed for the job!
While using standard reamers to clean valve guides, you probably have noticed that you have 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!
Photo by Jose Oliveros
Note: Reference Lycoming Service Instruction 1425A, SSP-1776 and SSP-578 and the appropriate overhaul manual or the appropriate Continental service information to determine which specific valve guide sizes you have and the required reamer size before purchasing the necessary cleaning reamer. Lycoming Mandatory Service Bulletin No. 388C requires exhaust valve guide cleaning every 300 hours for helicopter engines and every 400 hours for all other engines. McFarlane valve guide reamers are for cleaning carbon build-up only and must not be used for finish reaming of new valve guides.
|Part Number||Finished Ream Diameter
(Corresponds to valve guide ID)
(Corresponds to valve stem diameter)
|Lycoming Cleaning Reamers:|
|VGR-LC-KT||Contains one of each sized reamer|
|Continental Cleaning Reamers:|
|VGR-CN-KT||Contains one of each sized reamer|
Lycoming suggest using ordinary cup grease on the flutes of the reamer to remove deposits with the reamer rather than allowing the deposits to fall into the cylinder.