I use an APC 9/6, and with Power Master GMA 10/22 fuel I turned 17,800 (after break in) and if I switched to a Perry carburetor #1301 my RPMs went up to 18,300. I cant remember if the engines were run open faced or with a Nelson Ultra Thrust Muffler?   Eric

     Hello Todd, I've been using the TT Pro 36 engines in my 2nd string planes for the last 5 or 6 years and found them to be what I think is the stongest over the counter and out of the box 36 engine around. I also have a TT Pro 46 in a ex-Melton MO-1 which is now in Mike Potters hands. In my notes, my figures show that my 46 turned 17,600 with a APC 9/6 on Power Master 15% with the stock muffler on the engine. Without the Muffler it turned 18700?? I questioned that figure at the time but was to lazy to go back and re-test. I switched out the stock carb for a Perry 1301 and the RPM went down to 18400 (no muffler) which I ignored because I had never gone down in RPMs when I switched to Perry's.
     I've never used a TT Pro 40 so cant add any light there. I never thought of the 40 and 46 being as competetive in scale carrier as the 36 is in profile carrier.   Eric

As a simple first test add the muffler and muffler pressure to the engine.

If that helps but not a cure then clean the needle valve and spray bar.  I have found metal burrs in some new engines, not this brand.

Second test would be change fuel and or glow plug.

Clancy

Bob,

Was the TT 36 new, unmolested? 

It has been a while since I looked at the TT 36 throttle, but I would suggest that, with the throttle in the wide open position, NV set to 3 or 4 turns open, look down into the throat and see how much distance there is between the tip of the NV and the end of the low speed adjustment.

It is possible to get the low speed adjustment so far in (lean) that you can't get the main NV far enough out to get a proper high speed mix.

Cheers,
Jim

Yes it's a new engine, first time ran. Didn't mess with the low needle TT says it should be in the ball park but we know how that goes. The spray bar is a spigot and the low speed needle is probably at least 1/16 inch away from the end of the spigot when the carb is full open. High speed needle is way before the spigot and don't see how the low speed needle could mess with it.

Have another new engine and have a spare carb coming from another club member. Will be completely disassembling one of the carbs to see exactly how it feeds and also to see if I can't somehow install a low speed throttle stop screw. Looks like we will have 4 club members running this engine in fun carrier and none of us want to have to purchase another carb.

Yes it's a new engine, first time ran. Didn't mess with the low needle TT says it should be in the ball park but we know how that goes. The spray bar is a spigot and the low speed needle is probably at least 1/16 inch away from the end of the spigot when the carb is full open. High speed needle is way before the spigot and don't see how the low speed needle could mess with it.

Have another new engine and have a spare carb coming from another club member. Will be completely disassembling one of the carbs to see exactly how it feeds and also to see if I can't somehow install a low speed throttle stop screw. Looks like we will have 4 club members running this engine in fun carrier and none of us want to have to purchase another carb.

That first part where you said that TT said the low was in the ball park, and earlier when you said that TT recomends 2.5 turns out on the high end, you have to remember that usually their suggestions are with muffler pressure and you are trying to run suction.  EVERYTHING will need to be opened when you have less fuel pressure. I have had the same problem you are describing although not with the same engine.  I would suggest probably start at least 1.5 turns out maybe even 2 and work it in in about 1/8 of a turn at a time.

Actually first I would set everything to the factory settings with the muffler on and run it there like Clancy said to make sure everything works and for break in. Then if you want to run with out a muffler I would probably start 2 turns out on idle and probably 3.5 to 4 out on the high end, that should be on the rich side but rich is better than lean.

When you start with out the muffler I would start on idle and get it set first.  Start it and hold it there, if it dies and you have to prime it quite a bit to restart then the idle is too lean and if it is flooded then, you know, too rich. Once you have the idle set then that is one less variable to mess with on the high end. Good luck hope this helps.

David

An engine that won't go rich, if all the fuel passages are clear, could be leaking around any of the gaskets, also.  Backplate, head gasket, carb gasket and neck, any carb fittings, glow plug seal (and center post) are all suspect.  Many of the modern carbs have little gaskets where fuel nipples screw in, o-rings around the needle valve(s) or in the needle valve housings too.

Also, just the other night, I had an intermittently lean/rich needle setting - pulling the fuel nipple off near the high speed needle, and out of the chamber came a small blade of grass or some other vegetation that must have been floating in the chamber and sometimes obstructing, other times not.  Could even be just some old congealed castor in there.

Check out the pressure setup I have on my Seafire.  Just a piece of aluminum with a pressure fitting and it picks up fuel whether level or at 90 deg. On the ground It will start to sag when the tank gets low but as long as it is in the air and moving it picks up very well until it is out of fuel.  The pick up in the tank is ~17 inches away from the fuel nipple on the carb.  The plate on the port is just big enough to get the pressure fitting in the exhaust but not so big that it is restrictive.  I havent noticed any performance gain or loss in the engine with the plate on there.  The only reason I put the tank so far back was to help balence the plane out with that big 61 on there and it didnt fit that well when it was up farther.

David

One thing to remember here -- in Profile class, you can use the muffler if you also use the "Standard" 10% fuel supplied by the contest but you can't use muffler pressure nor even David's 'exhaust' pressure rig (at least by my reading of the current rules --

"3.3.1. The engines in the Profile Navy Carrier event shall have a maximum total displacement of .3661 cubic inch. Two-stroke cycle engines must be of the front-intake type. No pressure fuel systems will be permitted; however, the vents in the tank may be pointed forward in the air stream."

(Nowhere in the paragraph pertaining to 'exhaust system length' does it qualify THIS paragraph to allow muffler pressure in Profile Class).

I note that Eric changes out the stock carb for a Perry - that might be the best solution.

Im sorry for some reason I didnt put 2 and 2 together about running a 36 an it being on a profile. I guess I was just excited to show my setup on my class 2 because I was suprised that it actually worked.

David

You were absolutely right in bringing our attention to the no pressure rule, as we all know most don't read the rules and you could have saved an embarrassing situation.

Just a random input here. Some people here in California have been running TT 36's in carrier and they told me that on the newer versions of the motor and carb they have to run the needle way out, almost falling out. They actually put a piece of tubing over the needle assembly to make sure it doesn't vibrate loose.

Don't know if this will help but thought I'd post anyway.

Bob