40 FP Venturi

Stuka Stunt Main Forum · 8 of 8 known posts recovered

CMFoley · Mar 21, 2004 10:22 AM

Tower Lists two different size venturis for the 40 FP, large and small. Could someone enlighten me as to which one is the correct size for use on a Tower 40ABC with a OS needle assymbly.

Does anyone custom make the correct size which is better than the OS?

Thanks!

Mike

SRiese5283 · Mar 21, 2004 10:49 AM

#1 source

I make venturi's

Scott Riese

Crash2much · Mar 21, 2004 11:15 AM

#2 source

Leonard, our forum host, also makes very nice venturi's for these engines. Alloy or delrin.

Bill

I have no claim to fame, I build more planes than I fly, collect more kits than I build. That about says it, right?

Dick Fowler · Mar 21, 2004 11:45 AM

#3 source

My preference for the .40 is O.S. Max Part No. 23312100 which has an I.D of .268" and for the .46 the larger venturi which has an I.D. of .284". The O.D. of the larger O.S. Max needle valve assy. is .136".

http://www2.towerhobbies.com/cgi-bin/wti0001p?&W=000443397&I=LXCX06&P=K

LNeumann · Mar 21, 2004 12:17 PM

#4 source

The small one is correct and works well with the stock engine. When these engines came out, they included both venturis, and extra head shims. In later years they went through a series of venturi sizes, but for the stock engine with stock needle, the .265 is about right.

Leonard Neumann

JetJock · Mar 21, 2004 12:37 PM

#5 source

I just picked up a used 40 LA (RC). Would a .265 venturi be correct for it also?

LNeumann · Mar 21, 2004 04:00 PM

#6 source

>I just picked up a used 40 LA (RC). Would a .265 venturi be
>correct for it also?

Ordinarily, yes, and it will work fine. Since this has a blocked boost port, you can go to a larger size, up to a .278 or maybe .282. A lot will depend on the prop you use. The larger venturi would be for the larger size props.

Leonard Neumann

SteveMoon · Mar 21, 2004 06:35 PM

#7 source

Get both; they're cheap, and you can then figure out which
one works best for you.

Steve