I think I know the answer to this, but I would rather hear it from RCKen or Minnflyer. That could cause a lean condition on a remote needle configuration because your fuel line is leaking. Problem with that theory though is that the HSN is in the carb, and that is where the mixture takes place. If the leak is before the HSN then it shouldn't cause a lean condition. You should put a new piece of fuel tubing on it though.

The two step is normal.  It's the piston crossing over Top Dead center. . . the con rod snaps from one side to the other at TDC.  I'm not sure about the lack of pinch w/o the glow plug.  I'd have to check one of mine.</p>

My TTT PRO 46 was acquired used and has no gasket.  It's not a problem, but does lead to higher compression.</p>

Jack</p>

The fuel leak is interesting. I'll change out the tubing and see what happens. That could explain why it will still run at WOT but lose some rpms with the leaking fuel and pressure. I'll do some more investigating.

Now I am curious if either of my two Pro .46's have a head gasket. I defintely think you got something wrong with your mixture somewhere.  I am curous about the possible leak you mentioned with the head and cylinder liner. If there was a leak there, you would for sure have a lean problem as it would let in air, which would lean out the mixture. I have a VERY seasoned TT Pro .46 that has alot of miles on it and still has descent compression even after 13 years of abuse. Hopefully one of the more experienced Glow gurus will step in with a solution. </p>

Just a side note. I looked through the manual for the Pro .46 engine and it says to ensure the fuels you use at least has a small percentage of castor in it. I had been running pure synthetic up until recently.  </p>

Sounds like someone gave you bad advice. Lots of people will do that when its not their engine at risk. With a new engine, put a slightly smaller prop on. If normal sized prop is 11-6, break it in with a 10-6 or so. Loading a new engine with a large prop and lean run will surely cook it. A fuel with castor content will also help. Yes, it will slobber up your model a bit more but all that oil blown out the exhaust is also carrying HEAT out of the engine.

You use the high speed needle to adjust the high end. It should always be set at peak RPM (the steady high pitched scream) then back off a bit until it's burbling a bit. With an ABN (aluminum piston, nickel-plated brass cylinder) you don't want to run it in a blubbery rich setting without letting the engine heat up initially or you WILL ruin it. Peak it out for 10 seconds then back off slightly.

When you idle down, the low speed needle takes effect. Let it idle a bit. What I do is briefly pinch the fuel line while idling. If the engine speeds up a bit, you're too rich on the low end. If too rich and you suddenly open up the throttle it will stumble. If the engine dies immediately, you are too lean on the low end. Open the low speed adjustment perhaps &frac14; turn then try again. You may need to readjust the high speed needle.

Eventually you'll arrive at a proper setting.

Well the saga continues. I checked all the fuel lines and did not detect any leaks. I took the carb apart and cleaned it pretty well and saw no metal shavings or other obstructions. I still had the head off at this point and went to tighen it back down and noticed something interesting. One of the screws holding it on was stripped in the hole in the main engine block. Any advice for that little gem?

if you took the backplate off the engine and the head off at the same time.the screws are different (dont ask how i know) and will feel stripped when put into the head</p>

but if thats not the problem then run to ace hardware or similer and get some bolts (m3 most likely)
if the "nut" is stripped good luck.try locktite maybe ?</p>

This little engine is giving me such headaches I'm wondering if it might be easier to just buy a new one and use this one as parts. Ugh....

Can you post some pics of this thing? They would really help.

No, don't buy a new TT.46, go get a magnum,os or better yet, a supertigre 51. I have a TT42, not the same animal, but it took a while to get it right, it seems that the TT's have no mercy for lean runs, mine was almost cooked and lost due to my low tank position in the pulse xt.  

A new TT 46 is a great engine, much better than my magnum 46. If he has tuning problems, the bad carbs on supertigres won't help him out at all. A low tank wouldn't cause a lean condition, you can fix all that with the correct tuning of the HSN.

Well, on an air bleed TT.42, it most definatly will cause issues if the tank is set low in the plane, you see, I don't have a low speed needle to adjust the flow rate, and at idle the pressure feed is lowered due to the lower rpms of the engine. So at idle it runs hot to the point where if you pinch the fuel line it dies instantly, so if I tune it to peak rpm and back off about 300 -400 rpms to keep it rich, I can sustain an idle but not for more than 3 minutes before it loads up, if I open the airbleed it will idle too high and I almost have to shut the carb off to make it idle. Now the transition is alright but sluggish, it just seems to have a fine line your walking on with a single needle carb. Yes they are simple, when your not trying to suck fuel up to the carb, it will much rather pull the air from the airbleed than the fuel from below. I actually have many years tuning engines on models aircraft, cars, boats and being an ex automotive tech, I'm pretty good at tuning engines. But there are many things that can give a problem in an engine, bad fuel, plug, lean, rich, worn, low compression, high compression,excessive dirt, air leaks, loose componets, missing componets(head gaskets) and even the freakin stripped screw will cause an air leak, especially if it's used to hold the carb on, if you can't seat the head tightly, then it's going to pull excess air into it. Over the years, I've had maybe 12 supertigre's and only 1 was an odd runner, but that was to an slight airleak in the brass needle plate on the carb, simple fix, new oring lubed in dielectric grease and installed in a clean carb body. TT are good engines, but most ABC or ABN engines don't tolerate lean running, but that goes for every engine out there as well.

Whoa, I strongly disagree with this statement. While I like ST's also, the TTPRo 46, with a bit of castor, is very resilient. The first engine I really had to tune was a used beater TTPRO46 and I botched it up time and time again. It was so lean at times, it would deadstick, then too rich, blubbering all the way around the field. This was before Idiscovered RCUand RCG, now I know what I am doing, but that beater 46 still flies great.

Jack

So as a last ditch effort before buying a new engine I put some soapy water on the motor to see if it would blow bubbles showing me the leak. Well turns out I should have done this long ago. There was a slow leak between the cylinder head and liner in one corner. I'm sure this gets worse as the engine heats up. I'm going to get a new gasket since it has been missing since it was sent for repairs and see if that seals it up.

I'm still a bit worried about the stripped cylinder head bolt but it wasn't near the leak so hopefully I won't have to re-thread the block or anything.