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Old 08-30-2011, 05:41 PM
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chris6414
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Default 3.3 carb fix

Ok, been messing with my new(used) T-Maxx 3.3. Love the thing and have been into Nitro for the better part of 20 years. Planes, then helos and now trucks. This bugger just wouldn't seem to tune right. First super rich then tweak to running too hot. Checked the idle temps and could get it down to 260-280 after some full throttle runs and she would hold steady. Good sign, but still really rich after just sitting for long enough to take a measurement. Lean in an hour on the low speed and she would start rising again. After two tanks of this I started checking for leaks(air). Snugged the exhaust, nothing around the card throat or back plate. Then I started pulling the carb apart. First the inlet. Brass groove has some small debris in the grooves. Cleaned and reinstalled. Ran a bit, same thing. Also installed a filter and new tubing. Then I take off the end cap(silver) right below the inlet nipple and sure enough, the hole that lets the metered fuel in is about 10-20% blocked from the mold process. Plastic from the carb wall was actually in the hole passage. I didn't want to take a blade to it and tear up the passage so I took out the HS needle and gently put it in the passage and rounded out the hole till is was nice and smooth and round as it should be. Slapped her back together and refueled and now she purrs like a kitten(an angry one at that) It has a very predictable tune now and I could go about 5 hours leaner on the LS and the same on the HS with good running temps. I am sure they had a reason for the plastic carbs but a little QC from the owners could fix many of the "I can't tune this 3.3" threads we have seen. It is always that one little thing...