As a general rule how should I use my tachometer to setup the carburator needle, I mean from the peak rpm how far should I go back(500, 1000 rpm).

go w/manf recs.

but as a general rule use 150-300 for most glow jobs but again this is broad with both 2/4 strokes. adjust the low end for a good transistion from idle to full throttle.....

You can only use a tach to set a pumped engine. Non-pumped engines get leaner as the plane goes nose high and as the fuel tank empties. Nobody can tell you what rpm drop you should see on the tach because nobody knows where your tank is located. If you want to use the tach, you'll need a helper to hold the plane nose high. Also, make sure you only have about one ounce of fuel in the tank when setting the needle. Now set the needle about 100 rpm down from peak on the rich side.

The easy method is to not use the tach and make it rich enough so that when you hold it nose high the rpm rises but never falls back down from being too lean.

any other input will be appreciated

I agree 100% with Diablo, in regard to holding the nose high and watching for the engine to sag. Setting the high speed needle valve with almost an empty tank is also a good idea, as it is most conservative.

I can't believe more people don't try the method of holding the plane nose high when setting the needle. I haven't had much luck with the pinch test myself.

I also like to loop the plane near the end of a tank. If the engine sags, then it's too lean.


Robb

Another vote for Diablo. The nose-high test is as close to infallible as you can get. For my first run of the day, I normally pump just a couple ounces into the tank, start the engine and let it rev for a minute or two to get the heat up, then hold it straight up at WOT. If I am holding the plane back from flying out of my hands, then I know I have all the thrust I need. I give it 30 seconds nose-high. When you point the nose up, the rpm's should increase because of the leaner fuel delivery, then they should stay high until you lower the nose again. If you hear a falling note with the nose up, bring it down and richen a click or two. When you've got it right, then fill the tank and fly with confidence.

This is setting the needle for a good compromise between power and reliability, with the reliability foremost.

I use the tach mainly for breaking in and tuning a new engine, evaluating a change of prop/fuel/plug, or after an engine has been broken down and cleaned. I like to see a reading between 10-11,000 rpm at WOT with the needle on the rich side of peak (this is for my two-strokes up to 90 sized).

I use the pinch test as well, for a ball-park indication of needle setting on an engine I have not been running on a regular basis--typically a new engine, or when helping someone get their engine set up.