Here's a couple pictures of the reed-valves from my DA-170. There are no chips or defects in the reeds. but I noticed that they do not seal perfectly flat when at rest. Where they touch the reed carrier, you can see a darker color in the pictures. Where the reed is slightly curled away from the carrier, it is a lighter color. The reed is only about 10 one-thousands away from the carrier. I can't even slip an exacto blade in there. Does this matter? Should I turn them around?

I am getting a little bit of poor running at idle. I just replaced the carb diaphragms and was inspecting the reeds when I noticed this.

personally i wouldn't be to worried about it. the crank case pressure usually will push it flat and seal.

I was told it is the opposite of women, the flatter the better!!

What you have is not an issue, but a full seal works the best. Don't know how much time on that 170 but if it's less than 10 hours I wouldn't be too concerned about the idle yet.

If you handled the reeds they could have displaced the fuel mix that completes the seal.

Thanks. I engine itself has 62 gallons of gasoline thru it. But DA did an upgrade under warranty (replaced pistons, rings, cylinders) only 8 gallons ago (9 hours of run time). So I've been running Pennzoil Air-cooled oil at 32-1 since the new pistons.

Flip the reeds over. That way the curve will help seal them.

If starting and idle is good, there is no worry. Reeds will be tight when the crankcase pressure goes up.

Reed valves do not need to be completely closed when at rest. When you flip the prop the vacum in the case will seal it up. As long as your reeds are not frayed and the reed cage has no imperfections then your fine. The only benefit to having the reeds completely flat when at rest is you wouldn't have to flip the prop as fast to actuate the fuel pump in the carb. Which is based on the pressure pulses from the crank case. Hope that helps. Also in the carb itself is a screen that is hiding under a diaphram. If you were having any running issues that screen mght be dirty. Hope that helps.

Originally Posted by TKG

Flip the reeds over. That way the curve will help seal them.

TKG

sorry but i disagree, its harder for the crankcase pressure to flatten a convex (facing into the crankcase) reed than rather just to flatten the tip of one curling up. When its running maybe its ok, but when hand flipping, not.

otherwise i agree that slight gap will seal as soon as the engine is running

Originally Posted by MeTwo

Reed valves do not need to be completely closed when at rest. When you flip the prop the vacum in the case will seal it up. As long as your reeds are not frayed and the reed cage has no imperfections then your fine. The only benefit to having the reeds completely flat when at rest is you wouldn't have to flip the prop as fast to actuate the fuel pump in the carb. Which is based on the pressure pulses from the crank case. Hope that helps. Also in the carb itself is a screen that is hiding under a diaphram. If you were having any running issues that screen mght be dirty. Hope that helps.

slight correction. the vacuum will pull the reeds open and the air fuel mixture will be drawn in. but the crankcase pressure will close the reeds.

lol for sure vacume... pressure... All most the same just in the opposite direction.

Originally Posted by MeTwo

lol for sure vacume... pressure... All most the same just in the opposite direction.

it is the same. just depends on what side your on. lol. or is it the same only different? lol

Originally Posted by jamesrxx951

it is the same. just depends on what side your on. lol. or is it the same only different? lol

WTH LOL!!

I'm going to question that turning the prop to close reed valve is misleading.The prop isn't always going to be turning to cause the so called back pressure to close valve fully.At idle it may help.But getting the motor started will be rough.Correct to some extent I hope.

Originally Posted by Jimnoblesjr

I'm going to question that turning the prop to close reed valve is misleading.The prop isn't always going to be turning to cause the so called back pressure to close valve fully.At idle it may help.But getting the motor started will be rough.Correct to some extent I hope.

I'm not sure why you opened a string this old to supply totally incorrect information.

The pressure in the crankcase caused by the piston's downward movement, will seal this very minor opening, or any other slightly open reed.

There's no "if" to it. That's the way they work.

If you have a reed issue, it generally one that's got some physical damage. Missing, cracked or chipped are the bigger culprits.

Then again, if you want a perfect seal, go for it, but it's not going to change the way the plane runs one bit.