Coroer Edited By Chuck Larsen, Designee Director

SURE-GAP SPARK PLUG ADJUSTER — PRODUCT REVIEW Periodically a "new product evaluation" seems in order when an item appears that would be of interest to a number of our members. The following is about one of those necessary but often expensive special tools needed to properly service aircraft. Whether you decide to purchase or duplicate this device on your own it should provide an inexpensive, serviceable tool. If any of our readers have any materials, tools or techniques they think would be of interest to our members, please submit them for consideration. The design of aircraft spark plugs makes it necessary to use special tools to accurately adjust the gap. AC has met this need with their AV10-1 and AV15-1 gap setting tools currently selling for approximately $85 and $440 respectively. Champion offers models in the same category and their CT-415 currently selling for about $40. The Sure Gap Spark Plug Gapper offers what may be the answer to the economic complications of gapping your own plugs. This tool seems to do what the more expensive AC and Champion offerings accomplish for about $10. An added bonus is that it can be stored in a corner of your tool box in its 2" x 2" storage box. The photo and diagram demonstrates its simple design. It is a half-inch segment of 1" O.D. steel bored out and tapped to accept an 18mm aviation spark plug. (For you do-it-yourselvers this size tap may be available in a shop catering to foreign cars.) Two holes have been drilled and tapped directly opposite each other near one end. Thumb screws are turned into these holes and against the electrodes to adjust them. To use the Sure-Gap you first screw the tool onto the plug with the adjustment screws on top. The screws should be positioned so they contact the electrode(s) in the center by rotating the body of the tool right or left to raise or lower it. When the adjustment screws are properly positioned the electrodes are moved by turning them clockwise. (One quarter turn of the adjustment screw closes the electrode gap by approximately .006".) The electrode gap should be checked with a wire type feeler guage until the proper gap is attained. Opposing prongs on two and four electrode plugs can be adjusted simultaneously. Three prong plugs require the electrodes be adjusted one at a time. All normal precautions and guidelines for spark plug service should be observed. If you choose to buy rather than construct this little gizmo, Aircraft Tool Supply Company, Box 475, Oscoda, MI 48750 offers it for $9.95 plus $1.50 shipping.

SPORT AVIATION 17