Hi Peeps, I'm in need of some help please guys. I've started to dabble and getting to know the car. I've seen a couple of posts about the needle collar should be level with bottom of the piston, not bottom of the groove, is that correct? Sorry if this has been asked before, I couldn't find pics of the grooved piston. When tuning, the mixture nut seems to have little to no effect, could this be the effect of the needle which is currently set as below?