What is this?  It came in packaging that indicated that it was a Big Mig, and it has five transfer/boost ports (plus exhaust makes six).  But the side says "AMD" (or AML -- I'm not too good with Cryllic), and the venturi opening is huge -- about 0.1 inch, with a side needle that doesn't obstruct it much at all.

The reason I ask is that I'm not getting reliable running, it's kinda acting like it needs pressure, and it has that enormous venturi opening -- but it has neither muffler tap nor crankcase tap.  In the absence of any guidance I'm going to make a pressure nipple and press it into the back of the muffler -- but suggestions are welcome.

Pre revlite AME. Higher performance then the Big mig, more aggressive porting. Use a pressure system with it. Either muffler of bladder for consistant runs.
Dennis

Dennis, that clears up a lot of mystery.  I've lost the box and packaging, but I'm pretty darn sure that it said it's a Big Mig, and it comes with that plastic tank.  Either I was confused when I bought it, or something got swapped out somewhere along the line.

Given how nicely it goes in its brief flashes of brilliance, it should be the bee's knee's going that way all the time.

What prop should I run with this?  I've got things like 5.25x3, 6x2, etc., thinking that it's a Big Mig -- it sounds like I need something more closely resembling a toothpick, yes?

       How can you tell if it has AME porting from looking at the picture? I have both AME and Big Mig versions that look identical to that engines. My engine have the same letters casted onto them as well.  I'm pretty sure its a .049 from the .8 designation. In the event it came with that tank it could be a Big Mig Startup engine. Under the screen you will find that the hole is quite small in the Big Mig as a 31 drill won't even fit down inside the venturi. If you remove the plug look at the porting, three large ports excluding the exhaust is the AME version. Five small holes is the Big Mig version. Norvel also offered the Sport version which also had AME porting. The AME also has a larger venturi size as well usually too large for suction as I've found out lately. The others here have claimed that using muffler pressure improved its fuel drawing characteristics. I'm not trying to disagree here, I would just like to know for my own benefit how you can tell from the pictures. I've come across this many times on Ebay trying to determine which version it actually is. I've seen many of these engines mislabeled even from the factory. I know this was especially true a few years back when the website offered box damaged engine for under $30.00. Ken

       Tim, I own several Norvel Big Mig's. They're all new in the box and all of them have the five ports. These engines are run on the mild side. The larger 3 ports known as the (AME) version are used on all of my combat planes. AME was the manufacturer in the early 1990's. The cases are slightly shorter and generally all had the 3 port cylinders.  I own several of those and mine run very well. Your engine really shouldn't be having fuel draw issues. I've found that tank to be troublesome if your using that. I've seen guys rework the plumbing in those tanks and set them up for uniflow. I run my engine on a 3/4 oz standard wedge tank. I've never tried to use muffler pressure on the Norvel's so I can't comment on that. I do use bladders extensively but only on the AME versions as they don't draw fuel well. Maybe for an experiment, you could cap one of your vents and see if that improves your run. I do that on most of my 1/2 a's anyhow due to the siphoning when the props is turning. Is that a Top Flite 6x3? on the nose. I would keep your prop size in the 5" size and light on the pitch. The APC 5.5x2.5 works very well as does the APC 5x3. The main disadvantage to the APC 5x3 is the cost and the brittleness as they do break with light contact of terra firma. They run about $4.00 each. The 5.5x2.5 is less than $2.00. Some say the 6x2 works well but I've yet to see it. Sand the APC's well as they will dice your fingers. Your setup looks very similar to mine so I can't see why your having difficulty. Have you done any surgery to the tank? I always check to see inside if the pickup is unsoldered or cracked. I've found that to happen more than once. You have a clear shot to your spraybar and short line length so I don't know why fuel draw is an issue. I can see it being an issue if the tank has a pinhole leak or the backplate is leaking. Your venturi is glued in, check to see if its loose. I took a small adjustable to mine on the flats and wiggled side to side. I ended up using a little JB weld to hold mine in after cleaning real well. Ken

This does not solve your run problems, but the Norvel engines (the .049's and the .061's or rather the o.8 or 1.0 cc engines) with 5 intake ports are the Big Migs.  Those with three intake ports are the higher performance AME's.  Those three intake ports on the AME's are each significantly larger than each of those intake ports with the Big Mig's.  Ourwardly, you cannot tell the difference unless you can see inside the exhaust port and see all of the intake ports.

You might attach a Norvel muffler, make a new tank, and run muffler pressure to the uniflow vent.  The thing will wtill have plenty of power, even with the muffler on it.
 
Keith

Your all quite right about the porting. A serious brain freeze on my part. Still muffler pressure doesn't hurt but I'd as soon  run them on pressure when I do run them.
icture is of one that was run on a hard tank with a pressure tap from the backplate, Bladder is better
Dennis

...It did come with that tank, but it did not come with a pressure tap on the muffler, contrary to what I've seen noted on various web sites.

It does have the five ports.

Oh, I'm so confused.  I just want to get this engine to run consistently, without resorting to hemostats and surgical tubing and other extreme measures.

My first mufflers had no pressure tap. Getting a muffler from Bill is a good move. A 6x2 prop better fits the .061 but the 5.25x3 should work well with the .049. They need to rev up to maintain good venturi velocity for suction.

When I got my first Big Migs (.049CL and .061CL) you could get the tank for another buck OR you could get the "Start-Up" version with tank and spring starter for ~ $2.00 more. If it was a Start-Up version, it will have a small hole on the mounting lug to accommodate the starter spring...all else is standard Big Mig.

          Mark, I prefer all of the engines that you listed . I own a few of each. I think what you need to decide is how you want to fly them and for what purpose. I do use the hot rod versions for the combat stuff. I love 1/2 a combat but I've never participated in the event. My son does the flying and I do the pitting. I do have a lot of hands on experience with these engines. I'm speaking about the AME's, Norvel's and Stels engines. I recently though purchased a newer Revlite Norvel .049. I have this posted on another post in this section. That would be the Big Mig. I'm not trying to give this engine a bad reputation, but I've suffered with this one a bit. This would be the newer cylindrical shaped cylinders that are a grayish green somewhat like a phosphate finish. I've had terrific success with the previous versions which are referred to as the pre-revlite versions. These cylinders are typically nickle or brass finish. These seem to work real well for me in both mild and hot rodded versions. I haven't used the AP wasp, but I do own 2 of them. The only reason for this is due to the machine work required to provide a venturi that we use. Eric Rule from Rsm provides the Jan venturi for this engine in which it utilizes some of the r/c carb parts to work. Others have toyed with an adapter so that you can use a tee dee assembly. I may just try this. Out of the box though the Norvel impresses me the most. Ken