A valve arrangement in the cylinder head where the valves are at an angle to the cylinder bore. Canting the valves can make for a straighter path for air to flow into and out of the intake and exhaust ports. The area of an engine in which the air/fuel mixture is burnt.
There are lighters out there designed to burn up to 2500 degrees Celsius, so it is certainly possible to find one that is up to the task if you have a project that involves melting glass. One reason that most lighters will not melt glass is that they are simply not hot enough.
Incomplete combustion means less heat is produced. Also, a Bic lighter is most definitely transferring heat to the surrounding air. That heat transfer will further cool the flame. So 1970C is way too hot for a standard lighter. Unfortunately, most of the Internet incorrectly says this is the temperature of a butane lighter. But that's the maximum under laboratory conditions, which is completely unrealistic for a Bic.