I have a Zenoah G45 I have been tuning and have it running pretty good. I am pretty new to gas engines and was curious, where do you place the tack when taking an RPM reading? I put it about 2" being the prop about mid prop at it's widest point. I have noticed that it does vary based on where you place it. Where is an accurate reading taken from? I am turning about 8100 on the high side and about 2550 on the low side with a Zinger 20X10 prop. Does that sound about right?

Thanks all ! ! !