Fellows.
I am in need of advice. The guy I would've asked isn't available.
I have a Tower 40.

#1--- It needs a venturi for CL stunt. I am sorta capable of cobbling one but I need guidance on length and inside diameter.

#2---I need to know what size tank to get. I'm guessing 4.5oz.

#3---What recipe fuel should I be using?


I'm planning to build a profile Oriental. I do know that my guru (Clayton) told me to run a APC 10.5x4.5.

Thanks in advance.

What needle valve assembly are you going to use? An OS one or the Super Tigre style one? The size of the spraybar will dictate to some extent the venturi you need. An FP 35/40 venturi will fit. The large FP venturi was about .285 and the small was around .275 or so? Its been awhile since I played with the FP motors but the smallerventuri should be a good starting point.
Are any of Clayton's motors still floating around? They were setup by Tom Hampshire and ran really well...

I run a lot of these. More sensitive than LA46s to setup, but can be excellent and durable sport/stunt engines. I am partial to Jim Lee venturis .273. They have a longer tube than stock OS venturis. True or not, I think the Jim Lee approach smooths the airflow some. I'd start with 30 thousands head shims. Which means 3 Tower 40 head gaskets or 2 OS head gaskets. Leonard Neuman sells head gaskets for this engine. Check him out. Very reasonable. His gaskets are ten thousands. Which means 2 of these plus the gasket that came with the Tower 40. Free flowing tongue muffler. 10.5x4.5 apc. Powermaster 22%(50/50) 5% or 10%. Enya #3 or Thunderbolt RC long. I use the stock FP 40 through the venturi needlevalve. It clicks. But is not as fine a thread as the Supertigre and clones. Allow the engine to warm at least ten seconds then set the needle so it is 2/4 breaking back and forth on the ground. Then observe the engine as it flies. Click richer or leaner taking your cues from how the engine reacts during the flight. One click at a time, up or down, if you are close. Two clicks at the most. This is especially true for profiles, which are subject to vibrations issues more so than full fuselage planes. I like the profile tanks sold by RSM. The long one inch by 2 inches wide style. 4.5 ounces should be perfect with the above configuration. The Magician pictured bellow is powered by a Tower 40 as described. I fly it in competition. Works very well.

I just got my hands on one of these, myself.

What prop should I be using, at least to start?

Clayton's Tower 40, mounted on a Twister, ran very well. I believe that was the engine he used. Saw him fly at Brodaks.

What was the venturi size? Since you were using a supertigre needle the effective choke area was reduced, compared to using a large FP venturi with an OS needle. If the venturi is smaller than that, the choke area would be further reduced. The interplay of many variables determines an effective run. If the choke area was reduced sufficiently I can understand using the stock muffler and a 3 ounce tank. The Old Time pattern is, of course, much shorter than the standard pattern. I am surprised that the 11x5 prop didn't overload the Tower 40. These engines are usually propped with smaller props of less pitch. Could you pass along the size of the venturi. I measure them when popped out of the engine. Otherwise the calipers read all over the place.

Clayton's Tower 40, mounted on a Twister, ran very well. I believe that was the engine he used. Saw him fly at Brodaks.

He told me he would send it to me. Alas, it didn't happen. He flew the daylights out of that plane. One-flip starts. I know the engine is still good but I cannot get it right now.

Is the OS 40FP the same as the Tower 40? I see that RSM has a venturi for the 40FP. That would save me some agita.

Thanks. I remember that he told me the Tower was the old casting from OS but I sure didn't know which version.