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Engine basics => Engine set up tips => Topic started by: Bootlegger on September 26, 2021, 01:32:09 PM
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What location is the best for spray bar hole when changing the spray bar? Thanks
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The same as the one you took out, and the same as for any other engine.
Type at you later,
Dan McEntee
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Come on, Dan, that is a worthless answer if he removed the spraybar and didn’t notice the position.
The hole should idealy go just below horizontal to the airflow. Across is the theoretical ideal, but tests show that in the real world. 15deg below level works best. As I recall, you can go 0 deg, 30deg or 90deg. I go with 30deg.
My guess iis that the across position is only valid for linear flow. We probably have intermittent turbulent flow, so all bets are off except for real world testing.
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Come on, Dan, that is a worthless answer if he removed the spraybar and didn’t notice the position.
The hole should idealy go just below horizontal to the airflow. Across is the theoretical ideal, but tests show that in the real world. 15deg below level works best. As I recall, you can go 0 deg, 30deg or 90deg. I go with 30deg.
My guess iis that the across position is only valid for linear flow. We probably have intermittent turbulent flow, so all bets are off except for real world testing.
What did I say Larry? I know Gil, we have messaged and emailed many times. He is not new to the forum, with over 2700 posts, and this is certainly not the first engine he has disassembled, and certainly not the first spray bar he has replaced. I was speaking to his experience, which is he should have noticed, made note of, or other wise marked it's orientation when removing it. And barring that, it's the same as for any other control line engine that he has taken apart and reassembled. If he was a rank beginner or new to the forum I would have answered in more detail, but in this case , considering I was answering a question from a person of known experience, I didn't think that was necessary, still don't, and if there is any subject on this forum that has been discussed at almost infinite length, it's spray bar hole and it's position. So again, I was speaking to him and his experience.
Type at you later,
Dan McEntee
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Gil,
Did you ever find what you were looking for in Cox .09s. I sent you a PM but you never replied.
Herman
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The TD .049 uses the same spraybar as the TD .09. The spraybar has a octagonal end on one side and the circlip on the opposite side. Your committed by the flats of the octagon. It will index itself more than likely with the hole pointing down the venturi at the same angle of the venturi. There's no fine tuning it.
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Ummmm, not quite.
The question was about Medallions, not TDs which have an entirely different needle valve, spraybar and venturi setup, more akin to an ST "sprinkler" approach.
The spraybars on the Medallions have a hex shape incorporated into them (not octagon) which means that the fuel hole is indexed, as you say, in a limited number of positions in the red plastic venturi body. The ones I recall have the point of one portion of the hex pointing straight down the venturi. You therefore could go 60 degrees either forward or aft and try it there if you felt the need.
Dave
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Well I meant Medallion, not TD. Point being is that it's indexed which in most cases and the way it comes from the factory is pointing down the same angle as the venturi.