Dale C.

Think I am going to start making a few venturi for RC engine this way you can use your rc engine as a control line engine as well.
Going to start this sometime in 2023 I got a Metal Lathe I have seen this work on 4 stroke rc engines as well back in the 80s at a fun fly for control line flyers.
First one will be for my O.S. 61 SF ABC engine this engine is super strong and you can burn hole in the sky lol. I also need to learn how to make the needle valve for some of the engine I have.

aspeed

I have done a few dozen venturis. The stunt grunts like them with a fairly small bore. I made some needle valves too. Very time consuming with all the parts. I used 2mm pushrods and made a threaded collet to hold the part for doing the taper. Did it in two cuts because it sticks out so far. A grinding fixture may work better, and stainless steel wire might be an improvement. I threaded some 8:32 and 6:32 to hold them in the motor. Did not bother to split the ends and make a collet lock like the Supertiger type. I just use fuel tubing, maybe heat shrink would seal OK too. Made a few with an extra nipple to be a remote needle, but then there is another part to make on the motor.



die holder is not tightened in turret fixture, just grabbed by hand and let go when at the length desired or if it binds up.