CONCORD, N.C. – WKA has received several inquiries about the use of the light check in determining legality of cylinders, particularly those in the oval port TaG engines.
The light check inspection procedure is used in addition to the LAD gauge to ensure that the exhaust timing is within the limits specified in the 2012 Technical Manual. It is used with all Piston Port, Controlled Stock and TaG engines as well as the Comer K80. See the Technical Manual for the light check specifications for each of these engines. The procedure itself is described in detail on Page 118, Section 506.2.
WKA has developed the port timing specifications based on inspection and measurement of each engine when it is first submitted for approval. The specs are not based on manufacturers’ published specs, as WKA has found that these specifications do not always match the engines submitted for approval.
Engine builders should be aware that both the LAD tool and the light check are being used in post-race technical inspection. They should pay particular attention to any cylinder with a Nicasil plated bore that has been re plated, as the process of stripping the old Nicasil finish out of the cylinder can affect the controlling edge of the port.
As a final note, engine builders need to be aware that WKA measures port timing in fractions of an inch below top-dead-center, not degrees of crankshaft rotation as measured by a degree wheel or encoder.