Helping with tune on the internet is very difficult, but I can tell you that both the top and bottom needles on our discovery engine are just below flush. Also, I have noticed that our engines run best with Team Orion glow plugs. The best advice I can give is first to make sure the carb is sealed well and properly installed. Tune the top end making sure the bottom is slightly rich, then just keep dialing in the bottom needle until the idle lays down and doesn't drop, and of course turn down the idle. These engines run with a fairly lean bottom end. If you tune the bottom too fat, the idle will be all over the place (like with most engines). Last thing you need to know is the bottom end needle is fairly sensitive once you get it close. You don't need to make big moves with the needle, just the width of the screwdriver blade might be enough sometimes.