Cooking ignition

[Andrew Bird]

I bought a second hand 3w 170 on here a while back.

Went to run it for the first time and had no joy. After establishing there was no spark, I read into 3w ignitions only to hear mixed reports. So ordered a C&H unit.

In the past, in composite models, I've mounted the ignition module above the cannisters on the underside of the top of the engine dome.

Having spoken to C&H they say there are not the heat issues with their unit that the 3w unit can have but it can be an issue when you end a flight and let the airplane sit with the residual heat from the cans 'cooking' the unit.

Has anyone had any heat issues with units mounted around 1" below the cans? If I do this, the unit will only sit about 1" below them but have a better supply of cool air during flight and after.

[Tired Old Man]

Be a bit better off to mount the ignition on the firewall cone. More airflow and less heat soak from the ground. Down around the bottom of the plane you not only have residual engine and cannister heat you have the reflected heat from the parking surface. Good reason to point the cowl into the wind after a flight. I suppose either way will have it's own detriments. If you let the engine idle down for a minute or two after a flight you will avoid the higher temps obtained when shutting off after a high rpm run up or taxi.