thanks a lot for the tip Gray Beard I was doing what you suggested but my glow plug ignitor got discharged... one more question (if you don't mind) should I expect any drop on the RPM when I take the ignitor off?  I mean, once it is set up properly. the reason I ask this is because a guy from my club says with 4 S engines you always get this drop when taking the ignitor off, he says it is a normal behaviour on this kind of engines no matter how well it is tuned or how good the glow plug is.