Chances are that the contact area between the filter and the engine case is so small that relatively little thermal conduction is occuring between the two parts. Thermal conduction is a function of contact area and contact resistance. Unless you have a LOT of castor acting as "thermal grease" you probably aren't getting much conduction that will heat up the fuel. And, the fuel continues to flow thru the filter providing "cooling" to the filter housing so you should get to a steady state and stable operating point.
You can certainly experiment with better contact isolation, but you may be getting more heat transfer (in a full fuselage plane) due to trapped air convection if the tank is in stagnant pocket along with radiation heating. On a profile I can't imagine much of an effect. I have seen engine cases that were dinged from the filter constantly in contact (or just vibrating and hitting it repeatedly) and they ran fine.
Where I have seen hot fuel affect an engine run is on a rear exhaust racing plane with no heatshield between the stack and the tank. Runs fine for 5-10 laps, then leans out and gets flaky and quits. Should have gone another 30 laps, but the fuel was all boiled off.
To show how insensitive it can be, I attached a picture of a racing plane that did well at the Nats one year. Rear exhaust. No standoff baffle but just an aluminum heat shield. Might have been aluminum tape. Ran fine and didn't boil off the fuel which was important in an endurance event. He probably took home wood that year....
Topic: Fuel Filter touches engine case (Read 648 times)