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Basic question- sorry if it has been covered here ad nauseam- search function was no help. Neither was searching the lycoming O-360 operator's manual. What is the optimal idle speed setting on my carb for my O-360-A1D? On the ground at full rich, mine idles at around 800, goes down to 700 with the carb heat on, and runs pretty smooth at either speed. I ask because lately I seem to be getting long floats even when I nail my speeds, and I wonder if I'm making too much power at idle. I'm not in the habit of checking my gauges when I'm over the numbers, but I did on Saturday- my rpm read 850 after pulling the throttle to idle. I typically turn off carb heat on short final in preparation for possible go around. That float seemed endless though my airspeed was 70-75 as I started the flare. Could have just been the variable and gusting winds, or my being a crappy 250hr pilot...

So a mechanic serviced my plane when it wouldn't start and stranded me. Turned out to be a loose connection to starter switch. In the process of diagnosing, he pulled the bottom #2 and #4 plugs from my O-360-A1D. I flew home with no problems, but then got a call the next day from the mechanic wondering if he'd forgotten to put copper gaskets on the two plugs. Sure enough, they were missing on #2 and #4 when I pulled all my bottom plugs today. I'm going to replace my spark plugs for safe measure- they may have overheated since the gasket serves heat transfer as well as sealing under compression, and the plugs would have protruded too far into the cylinder. My questions: 1. Is there any real damage to my engine from this?? The threads in the cylinder heads looked ok to my eye. 2. What spark plugs should I use? Is is reasonable to use Tempest UREM37BYs? I am planning to replace all 8 even though they have only 200hrs. Regarding the latter question, my reasoning is as follows: I pulled Champion REM40E massive plugs from the bottom - all failed resistance test. I'd requested my shop resistance test a few weeks ago at annual but they blew me off. Oddly they also rotated these plugs to the bottom, and put my Champion fine wires on top- makes no sense at all. I'd expect the fine wires to have the same resistance problem. So I'm thinking of replacing all with Tempest UREM37BYs. People with hot running C models like mine have reported cooler temps in other threads by using these plugs. Alternately I could spend the money to put in long-lasting Tempest fine wires, but these seem harder to maintain with their delicate electrodes and sensitivity to sand-blasting. Given recent experiences, I'm all about doing my own spark plug maintenance going forward.