Not a total newbie to glow engines but I have a couple questions maybe some one can help with. I picked up a used trainer at a yard sale and it has a .40 engine that just says "Pro" on one side and "40" on the other. Is this a Super Tiger engine?.
Next question, it has a 10x6 Master air screw plastic prop , and I'm using 15% Omega fuel. I double checked my tack to make sure it was correct and I'm getting !8,500+ rpm with the HS needle about 1 1/2 turns out and it runs great at this setting. If I rich the mixture enough to get the Rpm back down between 14000 and 16000 it does not want to transition from idle to high speed and stalls out. Is 18000+ rpm normal or acceptable or do I need to pitch up on the prop or do something else. I really don't want to pitch up any higher and I can't go any larger diameter. Any thoughts would be appreciated.

The engine is a Thunder Tiger or Magnum 40 from the 90's

I doubt it turning that fast. Sounds about half again as fast as what the engine should be turning

Try to set the needles to where it transitions well

I doubted it too, but I checked it with another tach I have here at work (a Shimpo DT-105) it also read 18500 to 18700. I still doubted it, so I checked my new .46 magnum that I just finished breaking in and both tachs read the same on it (about 13700 cause its still a little rich). So I'm a little concerned about this .40 motor. Has anyone ever seen a .40 engine turn a 10x6 this fast and will it be safe to fly it like this?

Maybe a JETT or a Nelson with a little prop

Show us a picture of the engine?

G'day

If you are the USA and you point the tachometer at a light which is driven from the mains (fluro or incandescent) it should read 3600 rpm. You have 60 Hertz mains. Here in Oz we have 50 Hertz mains which means my tacho reads 3000 when set for a two bladed prop and I point it at a light bulb or fluro tube. A simple test for tachos.

Each cycle of the mains produces two pulses (as does your two bladed prop per revolution).

Is your tack at work designed to read a two blade prop, If not, you are going to have to devide the reading by 2 for a two blade, 3 for a three blade.

I have a Globee tack that breaks into these out of the park readings now and then. I think a lot of it has to do with the back ground and the color of the prop. It it isn't getting a good light/dark transistion, that may be doing you in. Also, if you have a light running on house current near by, that will also screw up the reading as the 60 hrz, 3600 rpm is going to show as a back ground.

Don

APC 10-6 at 18700 rpm is developing 2.46 hp. That is more than my tuned .91 FX so your little bone stock .40 engine is really performing mate

I will eat my hat if your tach isn`t broken or out of order in some way[sm=lol.gif]

Solved part of the mystery, the prop says 10x6 but it actually measures about 8 1/2". It's either mislabled or expertly trimmed down. Both tachs I have are industrial type digital tachs with an input shaft and various rubber tips that you physically push against whatever you measure. I used a concave shaped tip that fit snug against the end of the aluminum prop nut. I'll try to upload a pic , put a real 10x6 on it, and take some more tach readings. I've never uploaded a video but I'm going to try to video me taking the tach readings and maybe someone can see what is going on cause I myself don't believe 18500 even with an 8" prop. Will probably tommorrow before I can do this.

Hi!
You will see around 13000-13500 rpm with a APC 10x6 if you run 5-10% nitro!