Old Supertiger S35 venturi/spray bar installation

[Michael Massey]

My first attempt at joining the forum.  Hope this works.

I have an old Supertiger S35.  How should the spray bar be installed relative to the venturi?

The venturi has 4 small holes, 90 degrees in relation to each other.  The spray bar has one small hole.  Installing the spray bar into the engine casing hole that "guides" the spray bar through the venturi seems to have no particular orientation.  It certainly seems as though the spray bar hole should "line up" with one of the venturi holes but I do not know.  Can anyone shed light on this installation?

Tx.

Mike

[Wayne J. Buran]

Mike, I believe what you are describing is the standard Super Tigre sprinkler venturi. There is no orientation of one hole to another. However the hole in the needle valve assembly should be pointed directly into the groove around the venturi. The fuel will enter the venturi equally thru all four holes.
Wayne

[Busby]

Supposedly it will flow equally to all the holes, often it does not.
Busby

[Garf]

Just make sure all the tiny holes are clean and clear.

[john e. holliday]

I vaguely remember the Super Tigre's with the spray bar that held the venturi in place.  Back then I used them in Rat Race and Combat.  They were run on tank pressure from the crankcase.  Then I finally went to the pacifiers when I quit flying combat.

Just make sure the hole in the spray bar points towards the venturi.  DOC Holliday

[Air Ministry .]

 People used to say , about 30 years ago ,
 That Muffler Pressure was nessesary with those intakes to
 get an even run . due to air bubbles on suction tracking round the groove to the little holes ,
 so that it wasnt feeding consistantly.

 Anyone else heard of this ? .

[Paul Smith]

People used to say , about 30 years ago ,
 That Muffler Pressure was nessesary with those intakes to
 get an even run . due to air bubbles on suction tracking round the groove to the little holes ,
 so that it wasnt feeding consistantly.

 Anyone else heard of this ? .

I never heard of that problem.  They always ran fine for me - except if the venturi wasn't sealed air tight to the case.  Air leaking into the sprinkler ring kills the whole deal.

How would anybody know if the fuel flow through the several sprinkler hole was equal? 

I don't know if the sprinkler ring is full of fuel, full of air, or something in between.  I sort of assume that if the ring is sealed (as it must be), the air would get flushed out pretty quick and the ring would be fuel-filled, since there is no source of air to replenish what goes through the sprinkler holes.

[RandySmith]

People used to say , about 30 years ago ,
 That Muffler Pressure was nessesary with those intakes to
 get an even run . due to air bubbles on suction tracking round the groove to the little holes ,
 so that it wasnt feeding consistantly.

 Anyone else heard of this ? .

Hi Matthew
Yes I have heard that problem , however it isn't exactly as described, I had it happen to me many times. What would happen is at the end of the flight the tank starting to run out of fuel will add more air bubbles, and all the are between and around the case-venturie would fill with air bubbles and the engine would surge lean-rich with the speedup-slow down, and no amount of changing tanks would result in a clean cut off. What we did to fix it was either make a true venturie, or use JB weld and block up 3/4 of the 360 degree groove cut around the venturie, leave 2 holes open and it would then get a much cleaner shutoff

Randy

[Michael Massey]

Thanks to all.  I hope to give it a test run this coming weekend.

Mike M

[Michael Massey]

Sorry for the lengthy delay.  I installed the spray bar as recommended and all is well.  It turns out that most of my engine "quitting" issues were a result of the fuel.  I was using 10% Nitro with 28% Caster.  As soon as I switched to 5% Nitro and 20% Caster, everything seemed to fall into place (not the airplane, the engine performance.) . Thanks all for your input.

[George]

Questions and comments:

If I remember correctly, back when Super Tigre first produced the 35S (stunt), they also produced the 35C (combat). At the same time they retained their other G21 .35 in both RC and CL versions.

I THINK the 35C and 35S were plain bearing engines to save weight. I would assume they had different venturi sizes, and perhaps different port timing. Anyone remember? I never had any of those. My only ST .35 is the old G21 with removable crankshaft housing.

George

[Pinecone]

The C35S has a baffled piston, the C35C is flat top.

But they are bushing engines.  And I don't know about port timing. 

But looking on the Fleabay, it seems that C versions are much more common than S versions (even with RC carb) and the S versions sell for premium prices.

I have a couple of Cs and would like to pick up an S or two.