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check valve on pressure line?

Old 04-10-2005, 08:52 PM
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cstewa
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Default check valve on pressure line?

I have a new Saito 150 I am about to break in and I read about a guy putting a check valve on the pressure line from the tank to the muffler. Apparently this will pressurize the tank at higher throttle and then keep it pressurized at lower thottle settings.

Does this work? Or will it make the low end run rich?
Old 04-10-2005, 08:54 PM
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w8ye
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Default RE: check valve on pressure line?

One way to find out is to try it.

Generally it makes the low end run rich.

Enjoy

Jim
Old 04-10-2005, 10:03 PM
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gjeffers
 
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Default RE: check valve on pressure line?

i think if you put a check valve in without a regulator it might run fine untill you drop throttle and then it will be rich because the pressure will be shoving the fuel to the carb whether it wants it or not, and if (when) you kill the engine you will have a mess!

Good luck
Old 04-10-2005, 10:04 PM
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JoeAirPort
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Default RE: check valve on pressure line?

I think that would work with some type of regulator in the fuel supply line to the carb. Otherwise you are sending a constant 5+ psi of pressurized fuel into the carb. Normally the carb sees that pressure going from nothing to whatever the exhaust sends it depending on the RPM of the engine. So yes at anything but wide open it will be too rich and load up.

ORIGINAL: cstewa

I have a new Saito 150 I am about to break in and I read about a guy putting a check valve on the pressure line from the tank to the muffler. Apparently this will pressurize the tank at higher throttle and then keep it pressurized at lower thottle settings.

Does this work? Or will it make the low end run rich?
Old 04-11-2005, 02:09 AM
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Pepe J
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Default RE: check valve on pressure line?

I Tried it once and ended up with a totally erratic needle settings on the low end, usually on the rich side. Settings would change as the tank emptied. Constantly chasing my tail! If you need to do it , get a regulator, if not, leave it alone. Another thing to keep in mind, you have to un-hook the valve to fill your tank.
Old 04-11-2005, 06:10 AM
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FenceMagnet
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Default RE: check valve on pressure line?

Does anyone know of a source for the high-speed check valves like those supplied with the Cline regulator, other than through Cline.... the price there is a bit high....

[:-]
Old 04-11-2005, 06:44 AM
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w8ye
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Default RE: check valve on pressure line?

Tower hobbies and Central hobbies sell check valves

http://www2.towerhobbies.com/cgi-bin...L=++&search=Go

Enjoy,

Jim
Old 04-11-2005, 07:51 AM
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FenceMagnet
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Default RE: check valve on pressure line?

those are not the high-speed "good" valves....

[:-]
Old 04-11-2005, 09:44 AM
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w8ye
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Default RE: check valve on pressure line?

You had better look again. I don't believe you know what you are talking about?

If the Y-S check valve assembly is not the high speed good valve, the world must be turning the wrong way?

The check valve that comes with a Cline system is referred to as a "Duck Bill" valve. It is a rubber tube that is flat on one end. the check valve assembly slides inside the air pressure tube. This rubber tube of the check valve is typically stuck together on the flat end and has to be unstuck before it will pass air ONE way..

Jim
Old 04-11-2005, 10:36 AM
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FenceMagnet
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Default RE: check valve on pressure line?

"You had better look again. I don't believe you know what you are talking about?

If the Y-S check valve assembly is not the high speed good valve, the world must be turning the wrong way? "


Well, I DO know what I'm talking about, but I looked at your link too quickly to notice the YS valves.... thanks for the link

[:-]
Old 04-11-2005, 08:41 PM
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MikeSell
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Default RE: check valve on pressure line?

I read an article in RCM about using check valves that way. It explained it this way... The tank will only pressurize to the maximum pressure found in the muffler(usually about 5 PSI). Without the valve the pressure fluctuates widely (from 0-5 PSI but only able to maintain about 2.5 through the entire cycle.)
From my experience I would prefer a constant 4-5 PSI than a transient 0-5 PSI. If the throttle in decreased momentarialy the pressure will maintain but if the throttle is lowered for more time the pressure will reduce to the muffler pressure level.
As with any change in supply pressure you will have to adjust the idle and high speed needles. It works fine with engines with draw problems.
Old 04-11-2005, 10:28 PM
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michpittsman
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Default RE: check valve on pressure line?

I found the OS check valve from Tower is identical to the YS valve and two bucks cheaper! Been working on my 140L for six months now. Jim
Old 04-12-2005, 05:26 PM
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Pepe J
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Default RE: check valve on pressure line?


ORIGINAL: MikeSell

I read an article in RCM about using check valves that way. It explained it this way... The tank will only pressurize to the maximum pressure found in the muffler(usually about 5 PSI). Without the valve the pressure fluctuates widely (from 0-5 PSI but only able to maintain about 2.5 through the entire cycle.)
From my experience I would prefer a constant 4-5 PSI than a transient 0-5 PSI. If the throttle in decreased momentarialy the pressure will maintain but if the throttle is lowered for more time the pressure will reduce to the muffler pressure level.
As with any change in supply pressure you will have to adjust the idle and high speed needles. It works fine with engines with draw problems.

IMO this is a not a good solution to a fuel draw problem, some form of pump would cure that type problem. It may work in one or two configurations, but in most cases would create problems.
When I tried the check valve on the exhaust pressure line and chopped the throttle to an idle from full, the pressure would cause a rich, erratic idle. Then as pressure bleed, it would smooth out a little. The mid-range would be totally out to lunch and as the fuel level decreased, the settings would change again. You'll chase your tail trying to solve it!

Cstewa, as Jim stated, give it a try, but I'm certain you'll have problems. Those Big Block Saito's will suck fuel from a tank even if it was mounted in the tail! If you have a fuel draw problem, look into some form of pump / regulator.
Old 04-12-2005, 08:42 PM
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rajul
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Default RE: check valve on pressure line?

To get consistent runs, it's better to use a regulator with a check valve.

A small note on fourmost checkvalves: they have two types, one for glow (membrane type) and the other for gas (ball type). Both work well
Old 08-21-2018, 04:11 AM
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Default

Use this another way-
Petrol (gas) engines don't need pressurized tank, put a oneway valve in the gas tank air vent, if you set it the correct way round now it allows air IN to the tank when engine is running, but when you get the plane back home and stand it on it's nose the residual gas doesn't p*ss all over the garage floor

Last edited by smr2ley; 08-21-2018 at 04:14 AM. Reason: spelinng

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