Perry Pump
02-22-2008, 04:20 PM
#2
RE: Perry Pump
Would need to know which pump you have: The VP-20 ossilating pump or the VP-30 regulating pump.
They each have a completely different operating principle. The ossilating pump has only an inlet and an outlet on each end. The regulating pump has three nipples an inlet, outlet and a pressure tap inlet. The regulating pump is not really for four strokes as it requires a high pressure crankcase tap that is insufficient on fourstrokes.
The Ossilating pump can be used for both two and fourstrokes but the mounting is critical. The opposing inlet and outlets must be mounted in the plain of propellor rotation (not fore and aft) and works best if attached to engine back plates or directly on the engine mount itself. Mounted to the airframe behind the mount will provide very little action.
John
They each have a completely different operating principle. The ossilating pump has only an inlet and an outlet on each end. The regulating pump has three nipples an inlet, outlet and a pressure tap inlet. The regulating pump is not really for four strokes as it requires a high pressure crankcase tap that is insufficient on fourstrokes.
The Ossilating pump can be used for both two and fourstrokes but the mounting is critical. The opposing inlet and outlets must be mounted in the plain of propellor rotation (not fore and aft) and works best if attached to engine back plates or directly on the engine mount itself. Mounted to the airframe behind the mount will provide very little action.
John
02-22-2008, 05:03 PM
#3
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RE: Perry Pump
I have what apears to be the ossilating version. It has 2 nipples. One on each side. The person who built the model mounted the engine upsidedown on the mounts and has mounted the pump to the engine backplate. What I need to know is how to route the fuel lines to create the the correct flow of fuel. The tank has 2 lines coming from it.
02-22-2008, 06:51 PM
#4
RE: Perry Pump
OK sounds like the ossilating and and like it may be properly mounted. It does not matter if mounted below or like this one or if the engine is inverted, The nipple, still must point oriented to the side of the airplane.
The two line setup is oriented and plumbed like this, The pump merely goes in the clunk to carb line. After each day flying and this is important while the pump still has fuel in the line disconnect and loop one of the lines from inlet to outlet sealing in the fuel. If you do not do this and there is a long time between flight the ball chamber will crude up and the ball freezes, making the pump inoperative. If this happens that hex adjuster on the outlet end must be removed and the ball removed and the unit cleaned. They are quite reliable as long as the pump is keep sealed with a loop during non flying periods. There is moulded arrow on the front of the case showing which way the fuel flows also.
John
The two line setup is oriented and plumbed like this, The pump merely goes in the clunk to carb line. After each day flying and this is important while the pump still has fuel in the line disconnect and loop one of the lines from inlet to outlet sealing in the fuel. If you do not do this and there is a long time between flight the ball chamber will crude up and the ball freezes, making the pump inoperative. If this happens that hex adjuster on the outlet end must be removed and the ball removed and the unit cleaned. They are quite reliable as long as the pump is keep sealed with a loop during non flying periods. There is moulded arrow on the front of the case showing which way the fuel flows also.
John
02-25-2008, 12:51 PM
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RE: Perry Pump
Thank You for the assistance. I will follow your instruction. The only other thing I had was, can I take the other line from the tank (Vent Line) and run it to the muffler. I know that with the pump I don't need the pressure but I need somewhere to put that line so the tank vents and does not build a vacum. Also on the clunk line is it OK to take through a fuel dot before it goes to the pump. There-by using the clunk line to fill the tank and then the vent line will overflow into the muffler. Does that work.
02-25-2008, 04:26 PM
#7
RE: Perry Pump
Yes the muffler pressure line if avaliable is used as normal. Look at the picture of the black airplane and you can set that is the setup.
If you have exposed components such as the black airplane the normal fueling would be done slipping the clunk line off the pump inlet and fueling from there just as any other two line system.
In the case of a cowled engine it is my preference to still use a two line system. I always use a two line system on everything cowled or not. Arguably it will always be a more reliable method with fewer failure modes than either third lines with dots and sometimes capacity reducing extra third line clunks or mechanical fueling valves. At the very least it will save you scrambling in the grass for a dropped dot.
The method is simple and even handy for exposed engines with rear needle valves where sometimes its difficult to remove the clunk to needle line for fueling.
The clunk to carb line is or in your case the clunk to pump inlet line is made long enough to just run out and right back in two holes or a slot in the cowling. At this point the line is cut and a short length of brass fuel tube is inserted as a coupler. It is long engough that it can be pulled out just a bit and to fuel you just separate it at the coupler and fuel towards the tank just like any two line system. Recouple and push the ling back a little and you are good to go.
The two pictures show this set up both flush and pulled out and separated ready for fueling. In addition this method will also give you a place to clip on hemostats which are sometimes needed on inverted installations when the tank was not lowered enough.
John
If you have exposed components such as the black airplane the normal fueling would be done slipping the clunk line off the pump inlet and fueling from there just as any other two line system.
In the case of a cowled engine it is my preference to still use a two line system. I always use a two line system on everything cowled or not. Arguably it will always be a more reliable method with fewer failure modes than either third lines with dots and sometimes capacity reducing extra third line clunks or mechanical fueling valves. At the very least it will save you scrambling in the grass for a dropped dot.
The method is simple and even handy for exposed engines with rear needle valves where sometimes its difficult to remove the clunk to needle line for fueling.
The clunk to carb line is or in your case the clunk to pump inlet line is made long enough to just run out and right back in two holes or a slot in the cowling. At this point the line is cut and a short length of brass fuel tube is inserted as a coupler. It is long engough that it can be pulled out just a bit and to fuel you just separate it at the coupler and fuel towards the tank just like any two line system. Recouple and push the ling back a little and you are good to go.
The two pictures show this set up both flush and pulled out and separated ready for fueling. In addition this method will also give you a place to clip on hemostats which are sometimes needed on inverted installations when the tank was not lowered enough.
John
