For those interested, here is an alternative blip switch gauge. This is the same file as I've provided before (such as for use with the Classic Wings Camel (which it has since been included with)).
Included are instructions for installing it into the AF Avro 504K. This alternative blip switch functions more closely to that of the real thing, as with the real thing, the blip switch will only stay on as long as you hold the key down, and the engine will 'reignite' as soon as you release the key (so long as the RPM's stay high enough before you release the switch). The function is tied to the primer lever animation, providing the spring-like function to the blip switch. You will need to assign a key to the "Primer (lock)", and set the 'repeat' bar to the far right. I have this function assigned to a key on the top of my joystick, which falls right in the region of my thumb. Adding this will not interfere at all with the stock product's blip switch code.
The amount of use that the blip switch gets is one of the greatest misconceptions about rotary engine operation. The blip switch is only there for use in landing and ground operation, as most all rotary engines, save for a few, have fairly standard throttles. With the real engines, it requires various mixture inputs with any great throttle input, and if you don't get it right, the engine will quit, and you might not be able to get the engine re-started again. The blip switch is provided so that when decreasing speed on landing, the pilot doesn't have to be fiddling with the throttle and mixture positioning on approach, with the risk of losing the engine in doing so. The practice with most rotaries on approach to landing is to throttle down to half-power, and then use the blip switch to control the speed down to landing (this has sometimes been referred to as an art form). You cannot use the blip switch with the engine much above half-power, as you will risk serious damage to the engine.