stunthanger.com
Engine basics => Engine set up tips => Topic started by: Allen Eshleman on June 23, 2009, 04:01:05 AM
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Some Brodak stunt tanks have the engine flow line coming out of the tank below the wedge line. A friend of mind said that the venturi or engine needs to be lined up with the wedge line and that the flow of fuel to the engine starts at the back of the wedge bend. I never thought of that. If this is the case, is it true that the tank's wedge line is what needs to be lined up with the hole in the venturi or, as in the case of a Fox 35, needs to be about 1/8th of an inch higher than the hole in the the venturi. If this is so, does then I understand some of my engine problems where I tried to mount these Brodak tanks high to accomodate for the place where the line comes out of the tank.
Sub question - do McCoy 35's also need the tank mounted 1/8 an inch or so above the venturi hole?
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If you have a uniflow tank, the engine thinks it is sucking fuel from the end of the uniflow and does not know where the pickup is. I get best results with the uniflow at the same level as the hole in the spraybar. Others report different results. If you have not opened up the tank to see where the tubes go, you are flying on faith.
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My question is specifically for non uniflow tanks. I have been trying to get a good inverted run from a standard vented tank (I think that's what you call it).
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I am not able to get a run that suits me out of a standard vented tank.
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So, in your experience, you've not gotten good runs out of vented tanks. I have been thinking about switching to uniflow but haven't done so yet, except in the case of clunk tanks. I have at least two usable ones on hand. Per my other current article about tanks, I am getting a good run with a Hayes tank and muffler pressure on a Fox 35. I'm wondering if I can hook these clunk tanks to a motor that has no muffler - ie since there is no muffler pressure. I have an old Fox 35 and McCoy 19 that I still use.
I am wondering if some are getting very good runs from standard vented tanks.
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Allen, for the engines w/o mufflers, try running the vent tube to the front and into the prop wash, like I did with my Torp. I went so far on one plane, as to put one of those red filter pickups that go in the fuel tank for use with a crank or electric filler pump on the end of the vent. It acted like a funnel for the air, but proved to provide too much pressure causing a very rich run. When I took it off, the engine ran a lot better.
Glen
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In a standard tank - is the vent - the fill tube or the overflow tube. Did you close off the other tube?