The instuction sheet for my 3w-75 suggests using a engine mount between the firewall and engine. I don't know if they would be available in Turkey but, the two 3w importers here in the US sell them. The mount is a 6mm plate with holes loacated for more secure and conveinient mounting of your engine. I would mount this engine very solidly to that firewall, no rubber grommets in there. Balance your prop carefully and vibration will be minimal.