Choke Tube "stuff"...

Hi Juan, I just LoVe your engine configuration! I ran my engine yesterday late-afternoon on a new bench-mount for deck, on the back of our house.

I couldn't remember how I configured this test-engine.. and wanted to know for the record.. so I pulled the head and cyl. off to inspect.. and make sure I had a head-gasket.. which I did. Actually "two".. because they weren't new ones.

Standard (sport) glow-head.







Dual-bypass NON-SPI cylinder, thick-wall/slit-exhaust.



This translucent-white/horseshoe back-end has a copper reed and uses a circlip retainer. The needle is aluminum. I used my old Sig "Champion 25" glow fuel and the fuel-tank is of my own design. It's a "clunk tank" of approx. 12-13cc's.

I did run the engine yesterday.. but not before building a portable bench-mount. A "beam" style mount using one long wood-screw to secure it.

A few progressive photos of that..









It keeps oil from getting on the deck.. and also gives me 270 degrees access.. as opposed to the 180 that I had with the railing-mount.

There's a LOT more safe-clearance for any associated wiring. My elec. starter and glow-clip in particular. I hadn't run an aero-prop in a while... and didn't want any wires fouling this Cox grey 5 X 3.

The tool/accessories tray is handy.. and has a "lid" to keep-out the oil-mist. The power-panel is at the back.. which is best because it's the heaviest-component on the beam.

The bench-runs yesterday weren't indicative of any performance gains or loss. I didn't intend to upload these vids.. but I captured some "shorts" with my phone-cam.. and they're probably enough to draw your own conclusions.





This vid shows my electric-starter in action while "choking" the tube with a finger.. and then concentrates on the fuel pick-up in the little clunk-tank that I designed. It sucks the last drop of Sig Champion 25 out of that bottle.

Listening back to the 1st two vids... I'd say that there's maybe a 1K rpm increase "with" the flared tube installed.. but I can only verify by my "ears"...

Overlapping videos one and two, the pitch sounds pretty much identical to my ear. The engine was a little too inconsistent in video three.
One thing I will say is that the first video shows the engine running a lot steadier than number two, but I don't detect a difference in the peak rpm. It's possible that the slight restriction in the choke tube may effect airflow.

This quote copy/pasted here from my other choke-tube thread

balogh wrote:Roddie, I audiotached your vids, and here are the peak values I recorded:

No 1 vid:

No.2 vid:


I did not measure significant difference.

( To put it in the context of our discussions regarding "ram air charging" I meant under this term a setup, where the propeller air is blasted directly into a scoop on the carb,  whose axis is parallel with the propeller airflow..so those notes of mine on ram air charge do not apply to your bench runs where the carb air intake is perpendicular to the prop airflow.)

Thanks for the audio-tach readings Andras! Yes.. I understand and agree my friend.

Thanks Roddie and sorry for posting not to the right thread! The thread topics are somehow inter-related, anyway..

Oldenginerod wrote:Overlapping videos one and two, the pitch sounds pretty much identical to my ear.  The engine was a little too inconsistent in video three.
One thing I will say is that the first video shows the engine running a lot steadier than number two, but I don't detect a difference in the peak rpm.  It's possible that the slight restriction in the choke tube may effect airflow.

Hi Rod, Thanks for your input. Yes.. it would seem that the flared-tube used in video #1 promotes a smoother engine run. That in itself could be considered a performance gain. Video #3 was more about showing the clunk-tank's pick-up emptying the last few drops of fuel.

Great spirit of experimentation Roddie….. And going forward with the live fire test….. Always something to be learned from these kinds of things…… Appreciate you sharing them with the group

rdw777 wrote:Great spirit of experimentation Roddie….. And going forward with the live fire test….. Always something to be learned from these kinds of things…… Appreciate you sharing them with the group

Thank you Robert. I try to follow-through with my projects/experiments.. but I often fall short. It helps a lot when you people are supportive.

balogh wrote:Thanks Roddie and sorry for posting not to the right thread! The thread topics are somehow inter-related, anyway..

No worries Andras. I always appreciate your interest in my activities.

So Roddie I like this little fuel tank , is it a pill bottle ?
How did you leak proof the lid ? Thanks

akjgardner wrote:So Roddie I like this little fuel tank , is it a pill bottle ?
How did you leak proof the lid ? Thanks

Hi Joe, It's a 1/2 ounce (15cc) plastic (P.E.T.) bottle. I bought a 12pk. from Amazon. The screw-on caps have their own foil/paper seal which seems to work well.

Here's a few pics.. but check out the link to the build-thread down below.







Here's the thread..