Good morning. I have a Extra 300s .46 size (tower hobbies engine) that flies real well, when the engine is hitting its stride. The problem I am having is when this particular engine is fit with the cowl, it is much harder to start since I must open the carb to full, place my finger on the carb and counter-clockwise turn the prop so that the fuel gets in the carb for combustion. Is there another way to fix this problem? Does the engine need more air for the carb? I also have a small vibration from the mount on the high end needle that is loose from a screw that does not fit snug. It does not catch on the thread. I am kinda lost guys.

choke off your muffler then turn the prop.

The stripped screw could be a problem. You might need a new carb barrel/housing. Or a sh*tload of Loc-tite.

There is no law against opening up engine cowlings with Dremels (the sanding drums do this FAST!). You should be able to get the fuel to the carb by running the elec starter on it for a second with the engine throttled up but no voltage to the glow plug.

open up the cowling a little with a dremel or some kind or rotary tool where the carb is. but if the engine runs just fine with the cowling on but has trouble getting it primed then just open the throttle, put your starter to the engine and put your finger over the exhaust. this will do the same thing that covering the carb will do. but i would still open the cowling a little around the carb unless there is quite a bit of room anyway cause then it will get more air.