Internal Stinger Size for .21 Pipe?

[Blackout]

I'm going to add a brass internal stinger to a NR .21 nitro pipe for my JAE rigger running a .21 NR 5-port engine. Is a .283" I.D. for the internal stinger o.k. to use?? Or would another size offer better performance?

Thanks.

 

[Norm Doerr]

Just started revisiting this again. I would try a bit bigger around the .300" range. What is it now?

 

[Blackout]

It's .285" now, but the pipe stinger's I.D. gets larger so if I cut 3/8" off the length I can start using larger brass tubing if I have to. Then just bring the stinger length back to stock length with the longer brass tube internal stinger.

 

[Terry Keeley]

http://www.jrcbd.com/showthread.php?t=16312&highlight=internal+stinger

9/32" is fine, remember if you choke down the stinger it increases heat to the motor and also pipe pressure which in turn can make the needle rich.

 

[Blackout]

http://www.jrcbd.com/showthread.php?t=16312&highlight=internal+stinger

9/32" is fine, remember if you choke down the stinger it increases heat to the motor and also pipe pressure which in turn can make the needle rich.

Thanks Terry.

 

[anthony_marquart]

I haven't been able to test and prove this myself but my studies have shown that the stinger length is as, if not more, important than the ID. You can add heat and back pressure with stinger length and not restrict the airflow as much as a smaller diameter.

 

[moparbarn]

anthony, if you add an internal stinger make it stop inside at the metting point of the 2 cones, or midddle of the flat band. alos, make sure the stinger is centered EXACTLY inside the pipe - it do matter

. IF i remember correctly

, rod geraghty told me that somewhere around .012" to .018" smaller diameter stinger than carb bore for .21's. i know on .21 k&b's with a black carb bored to .300", he set the stinger at .287". for my cmb goldhead TT's with a .320" carb bore, he was at .300". it's gonna vary some by timing #'s, pipe, engine, hull, prop.....the TT was for my sundowner ob rigger, maybe bigger diameter for breathing at higher rpm's? GENERALY speaking, larger diameter for rpm's, & smaller for torque. terry's right, a smaller stinger will cause a rich needle, sometimes quite a lot. but it will give you more consistent needles throughout a tank of fuel, & less leanout/dying during throttle transistions.

 

[Blackout]

anthony, if you add an internal stinger make it stop inside at the metting point of the 2 cones, or midddle of the flat band. alos, make sure the stinger is centered EXACTLY inside the pipe - it do matter

. IF i remember correctly

, rod geraghty told me that somewhere around .012" to .018" smaller diameter stinger than carb bore for .21's. i know on .21 k&b's with a black carb bored to .300", he set the stinger at .287". for my cmb goldhead TT's with a .320" carb bore, he was at .300". it's gonna vary some by timing #'s, pipe, engine, hull, prop.....the TT was for my sundowner ob rigger, maybe bigger diameter for breathing at higher rpm's? GENERALY speaking, larger diameter for rpm's, & smaller for torque. terry's right, a smaller stinger will cause a rich needle, sometimes quite a lot. but it will give you more consistent needles throughout a tank of fuel, & less leanout/dying during throttle transistions.

Good info, thanks for sharing.

 

[anthony_marquart]

What would be the difference in an internal stinger and external,.. not physically of course.. I've done the internal stinger thing,.. not sure I had much change other than sound.. and not sure it was lower decibel,, but pitch change I think,.. and for the better..

Also if you pressure tap is all behind the internal stinger inlet, would that effect tank pressure?

 

[Ed Knudsen]

Before installing the brass internal stinger drill a small hole thru the stinger (1/8"-3/32") at the point were the stinger intersects with the original aluminum stinger inside the pipe. Doesn't effect performance and will allow you to drain water or fuel out of the pipe in case of a dunk or if the engine gets flooded. Hope I explained that right.

Ed

 

[Terry Keeley]

What would be the difference in an internal stinger and external,.. not physically of course.. I've done the internal stinger thing,.. not sure I had much change other than sound.. and not sure it was lower decibel,, but pitch change I think,.. and for the better..

Also if you pressure tap is all behind the internal stinger inlet, would that effect tank pressure?

Been running them 10 years now and all I see is it's quieter.

Tap in the converging cone should make no difference.