There is a fix for your sick tower hobbies .46 engines, I read all of the comments and symptoms of this poor "MISFIT" engine that we are all burdened with, Well my engine did relate to 100% of them, but not anymore. First of all the tower plug is not standard length and they will not work with this engine, Install a "FOX" idle bar plug, Not os #8 nor the # 3 for that matter. I'm sure they have their uses elsewhere. Change that darn rear needle carburetor to a front needle carb from a GMS .47 if you get dead sticks and you see bubbles in the fuel line, Also my engine has 2 head shims which make the compression a little high. I can get a very reliable low idle and only using a castor synthetic "5% nitro" fuel at 4300 feet of altitude, if you use higher than 10% nitro fuel in this engine then you will risk blowing glow plugs and probably detonation unless you use more head shims, My suggestion is as your engine gets older, use the higher nitro fuel so that it will run better because the tolerances weren't as good as when it was newer ( Here is a riddle of this relevance) The older I get, The better I was..... Let me know if this remedy works for your engine as it did mine, I know for proof of compliments from club members, I have a tower trainer with a tower .46 abc engine that climbs out like a homesick angel and it thinks it's half pylon racer.....and not one deadstick landing....Happy landings...