gkaraolides

On a more practical level... I have one of these Webra backplate-mounted pumps that I bought many years ago. It needs service now. Webra can supply the spare diaphragms etc. but I have no idea how to take the pump apart and put it back together again. Taurus Flyer, can you give me a couple of pointers on how to do this?

Best regards,

George

Taurus Flyer

George,

Webra, right choice

When you look at the backside of the black (nylon?) bottom, you see the adjustment screw of the pressure regulator. On both sides of the screw there are little holes, see the green arrows on the picture 1.
For us this was an indication these holes are probably to position the regulator when fastening the pump/regulator in the aluminum housing.

For that we did try to screw open the aluminum insert out of the housing, see picture 1.

There is a fine thread used to mount these two parts together with all the internals in it as a sandwich.
It was possible without any tool to open the surprise, but when not possible by handcraft try by rotate the aluminum inside with a tool but protect the material with a piece of cloth or else.

Be careful with the fuel connections and DO NOT REMOVE THEM.

When you can open the housing the inside parts you can assist to come out by blowing on the crankcase side of the housing. (Hanna’s suggestion, see is the physicist I am the engineer!)

For the diaphragm you have to unscrew the little nut and remove the valve to separate the diaphragm from the valve seat part.

After the diaphragm is separated you also can remove the screw and two metal plates from the diaphragm. Take attention for the position of the valve on the screw.
The valve is mounted between two nuts and it is good to give the valve the same position when mounting the new diaphragm, because of the “work point” (compensation of the proportional fault of the regulator! LOL)

Success, and we are interested in the progression and if we can help, ask.

Hanna and Cees

kochj

In reading through this post, I try not to be bias, but couldn't help thinking of the head ache's I had had with using the perry pump
on a OS 120AX 2-stroke.... I had tried many of the sugestions but in the end, just removed it.
It ultimately (couldn't prove it) caused a head gasket, to MELT to the head.... Lean run? I just know that things were either
very touchy needle setings or non-responsive to needle changes....

It seems that 4-stroke engines are where all manufactures are placeing there R&D and, try the built-in pumps..
Obviously, we are talking about Alcohol/nitro/Glow engines, as gas doesn't have the same issues...
The price of a pump makes the price go up 100+$'s and I understand why others are willing to give it a 30$ perry pump try...
I am not so willing to tinker with this anymore, even though I was very determined to make the prevy setup work...

I recieved a New Engine out of the deal, and am running it in a QQ yak 54 69"... and I may be having fuel draw issues with the Tuned pipe installed
on it....I didn't get the chance to fly with the stock muffler, to compare, but this model would benifit from a fuel tank placed next to the Main wing tube, due to
dramatic change in CG when the fuel runs low.....

too cold to try it now, but maybe a Spring project...

Lazer

My Feedback: (27)

I've enjoyed the conversations and it's cantor. Keep it up.

I have just one question that relates to the older Perry Pump I have before the ones offered now that is diaphragm operated will or will not work on my OS .91 FS Surpass and what would be the least expensive, but dependable. I'm thinking that I will be using a newer engine if I can trade for one. I've found an OS 1.20 FS II Pumped that should pull a 8.5 lb plane very well on a prototype OS pipe I came across. What ever ideas come out of this will be great.
TMc

mike31

My Feedback: (67)

I have one of these for sale. Anybody interested? email me at [email protected].

gkaraolides

Many thanks Taurus Flyer for the pointers on how to disassemble the Webra backplate-mounted fuel pump. Mine is slightly different to yours, the backplate is all metal. I will start a new thread on it and take some pictures.

Best regards,

George

Taurus Flyer

George,

Is your pump really a Perry, because I did see also more complicated backplate pumps/regulators all metal and with more adjustments and connections, maybe OS Max or ENYA.
This was a reason for me to make the pictures, so we can check if we talk about the same pump.
When the pump has three connections, it's working probably like a Walbro, so I am interesed in info!!

Cees

guille2006

I've the same perry pump on a Supertogre 90 and works beautifully. Just take care of the vertical position nad the lead indication fuel flow direction.
Before installing that, check the tube to the carter; sometimes it hardens and brokes... a new ona is reccomended to use every 1 year.
Cheers
G.

NM2K

My Feedback: (14)

Unless you are interested in flying FAI pattern competitively, you will not need a tuned pipe for a four-stroke glow engine. Their sole purpose in competition is quieting, not power gain, though some try to sucker others into believing that their setups do provide a power gain over other setups. What they ultimately do is to not restrict the exhaust when compared to open exhaust, which is not the same thing as a true power gain.


Ed Cregger

hook57

My Feedback: (21)

Disregard....

Taurus Flyer

Lazer, You start a thread, everybody receive a lot of posts and you still have not all the answers!!
I did write, we only use (pump assisted) pressure controller(s) but I did ask my Physicisticated Hanna about your question, the pump on the four stroke glow engine and this is what she writes, read!

Hallo Lazer,

Taurus Flyer did show you how the pump works (your post 4) but now another question and my advice.

I am theoretical not enthusiastic about a pump on a four stroke, it does not make me happy.

First reason
A glow engine does suck the fuel only ÂĽ cycle time
But the other ¾ cycle time, while the engine is compressing, burning and exhausting the mixture, what is that pump doing on that moment? Waiting? No want the spray bar isn’t closed and the piston is pulsating a second time the crankcase pressure.
I think that the standard pump, as we know now, with it's constant (about) 0,25 PSI pressure, is pumping a second moment a little bit fuel in the engine near the closed inlet valve.
And that fuel maybe is waiting to blow out that little tiny candle in the cylinder, we all call the glow plug, the first moment the valve opens.

That little bit extra fuel wasn’t "spray barred" too, because with that closed inlet valve there was no air that second moment!!
So liquid fuel, wasted money? I am afraid so and so not Typical Dutch.

Second reason
The second problem still can be the mid and low range fuel adjustment when using a standard carburetor, because of that higher than normal inlet fuel pressure.
In mid and low range this pressure is relative some more when compare with the sucking pressure than in full power situation. So try to “second needle” to keep the money in the wallet seems to be a lot of experimenting.

Conclusion
These are the two main reasons I do not recommend to use a pump like Perry on the four stroke.
Let it be clear, I am a simple cat so maybe I am wrong.

Regards Hanna

Taurus Flyer

Lazer,

for information only

The pump and pressure controller as built for the Orion left side.
The pump is driven by the crankcase pressure of the Enya 60 4C, but the combined regulator is like cline.
This combination you can compare with a Walbro carburetor.
The amount of connections show us this is more complicated than a Perry pump (right side).
There is a sixth input on the backside to sense the airpressure in front of the carburetor input.
It is this picture that shows us also you need a lot of R & D to make a reliable and accurate fuel system for a 4 cycle I think.

Cees

Lazer

My Feedback: (27)

Thanks TF. I see what your leading to on this. I think what I'm going to do to help eliminate as much complexity as possible by purchasing a good used engine with the pump and regulator match for the engine they are mounted on.

Taurus Flyer

Lazer,

Of course it is still interesting to hear if anybody has positive results with a pump on a four stroke and of so, which combination and circuit it is.
Success with looking for the power plant.

Cees

Sport_Pilot

When people use the regulated pressure pump on a four stroke, there are another two things to consider that often makes this work.

1. You must tee the line from the crankcase to pump with a drain line to allow oil to get out. This weakens the pulse, but this is made up because it gets to pump twice.
2. You must bypass the line from the carb back to the tank. This reduces pressure so that the carb will only take fuel up from its on suction.

Taurus Flyer

Sport Pilot,

For point one you are right,
In my Orion there is a line mounted from the crankcase connection to the bottom of the plane to allow the oil to go out. In the line there are two restrictors, between the restrictors there is a T for the upgong line to the pump.
The pump is mounted between backside engine and firewall. Engine is mounted upside down.
Point two I don't need because I use a "Cline like" regulator in the combo.

Thanks Cees

YellowBlueBird

Any tips on using a perry pump with an evolution 60nt? Is the back plate really thick enouth for the drillilng and tapping? I want to put the fuel tank over the cg for two reasons. first the obvious and second I have not found a decent size fuel tank that will fit nicely in the nose of my Primus/Tarus. The OS 61 used in an earler one was just a bit to bulkey for that width of the nose.

Taurus Flyer

YellowBlueBird,

No, normally the backplate is not thick enough for drilling and tapping, my opinion!
Better solution is to look if you can use one of the four screws that are used to mount the backplate on the crankcase.
I also can show you how I do mount the fueltank in a Taurus.

Cees

Taurus Flyer

Gents,

On request in Redesign and reconstruction of the Oldest Taurus on Earth post 678 pagina 28

Cees

bubba153

Can't comment on the evolutions, but I've tapped the backplates on various OS, K&B, and ST in the past without issues.  The threaded part of the pressure tap will extend into the crankcase and will have to be ground flush with the inside of the backplate.  After doing this, I've just used some RTV on the pressure tap's threads.  There isn't a lot of metal supporting the pressure tap, but so long as you don't lever on the nipple putting the pressure line on, I didn't have any problems.  It's in an otherwise protected location.

Taurus Flyer

You always can recognize the place where the engine designer did located the position for a pressure tap, if there is not such a location visible I only can advice make the tap in the screw of the crankcase back plate.

These visible locations are special designed because they left away all the material to safe weight.
Even in the past the back plate screws were often used to make a tap.
Third position for me would be in one of the two bearers between the mounting holes!

I did make a picture of the OS Max 61 FX, right side, the engine were we are talking about I thought, the other is an MVVS 10 CCM, both modern engines.

Cees

g_mkoch

[img]file:///C:/DOCUME~1/UserXP/LOCALS~1/Temp/moz-screenshot.png[/img]Just a question:
Here in the specifications of the VP 20 Oscillating Pump says that it may be also used in 2 cycles engines.
Have one of you guys used one of these pumps (VP-20) in a 2 cycle engine?

790

Has anyone tested the Webra fuel pressure regulator? It uses a slightly different approach by pressurizing the fuel tank via the case then regulates that supply by muffler pressure to match engine speed. Sounds good and doesn't mention a need for a special carb.

[link=http://www.webra-austria.at/motor.php?folder=ACCESSORIES&lang=EN]http://www.webra-austria.at/motor.php?folder=ACCESSORIES&lang=EN[/link]

Sport_Pilot

You don't need a special carb for the Perry system either, most twin needle carbs will work, but air bleed types do not.

Taurus Flyer

790,

The Webra fuel pressure regulator.

I did not try the Webra regulator but read the description and for me they are nearly all the same so I give you my two cents!

Webra let you connect the reference input for the controller with the connection of the muffler.

Background of the principle is:

During flight the regulator will control the fuel pressure to the spray bar of the carburetor equal to the pressure of the reference input of the controller, so in this case the exhaust pressure.
This way of connection the result is, the carburetor is feed with the same pressure as normal when the exhaust connection is connected with the air input of the tank.
Your profit is, the position of the plane doesn’t any matter, the ratio of fuel and air is like horizontal flight with “no regulator” and the standard carburetor.

Some points to think about:

First, mount the controller as close as possible near the carburetor, see the picture for example.

Second point is, the exhaust pressure is pulsating, when you cannot adjust the fuel air ratio adequate you maybe can put a restrictor (and capacitor) in the line between the muffler and the reference connection of the regulator. Normally the tank pressure is an evenly average pressure of the exhaust pulsating pressure.

Third point is, be aware of the tank pressure when used a crankcase tap, it can rise to 5 -7 PSI, enough to pres the fuel 20 – 30 feet above the plane!. Think about where we can find the hydrocarbon liquid when something goes wrong in the plane!!!! ( google for “Koseq”)

No engine pressure tap?

Because we normally do not need such a high tank pressure when the tank is mounted behind the firewall, I use the exhaust connection and a check valve to pressurize the tank , see the picture.
The reference connection of my controllers/regulators I connect with the brass tube in same position as the air intake of the carburetor, this way I realize compensation of any (airspeed!) pressure near the air intake also when the engine is mounted inside a hatch.

Keep in mind, the Webra regulator you probably also can use the way I do, see the blue and orange arrows.

If there are more questions I maybe can answer, please ask.

Success.

Cees