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  1. #1
    1QwkSport2.5r's Avatar
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    TT .46 Pro w/ Perry VP30

    I am using this engine on a scratch-built airboat seen here: http://www.rcuniverse.com/forum/m_10..._4/key_/tm.htm

    I ran into issues with fuel draw having the fuel tank 6-8" away. I could get the engine to run pretty good in the upper RPM but it would quit at idle. I assume this to be because the idle needle needed to be opened up a bit more to get fuel up to the carb which then flooded the plug. I installed a VP-30 pump to help with the fuel draw problem and this netted much better results. In order to get the engine to run good, I had to back the regulator screw out quite a bit. I didnt take the screw out so I dont know how much is left but I cant imagine there's much left. At WOT on a 9x7 prop, I was getting 16,200-16,500rpm peaked. I could not idle it lower than 3500rpm because it'd slowly idle lower and eventually sputter and quit. Probably due to excess fuel. It will idle for quite awhile at 3500-4000rpm but I wonder if I could get it down to 2500 or so.. I peaked the engine with a tach and adjusted the idle mixture for perfect transition. Engine runs good and sounds good, however if left to idle for more than 4-5 seconds, the midrange ends up rich and rough (I use a 7 second count then jab WOT and if its nice and clean I leave it). Leaning the idle mixture any more raises the idle and it cuts out in transition so I richened the idle mix so it doesnt cut out. It still will have a rich transition after idling for more than 5 seconds. Less than 5 seconds at idle and it transitions like a dream. I've seen several threads relating to adding a bypass to return excess fuel back to the tank but I wanted a little more input in regard to my particular installation. Here's a pic with the pump installed (sorry its a little fuzzy, I was in a hurry)


    If I run a return line back to the tank, would I then be able to screw the regulator screw in (increasing pressure) so it doesnt fall out? What kind of idle rpm should I expect from the engine being inverted and run on the pump? I like to see 2500rpm or less for idle but I dont know if thats realistic. I need ultra reliability since a stalled airboat means I'm casting a fishing line out to recover it and sometimes the wind blows the boat away from me.

    Thanks in advance.
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  2. #2
    Moderator w8ye's Avatar
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    RE: TT .46 Pro w/ Perry VP30

    I would at least try the return system with the tee right next to the needle valve
    Attended the CutFinger Institute of DirtNap University for years but never did graduate....
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  3. #3
    1QwkSport2.5r's Avatar
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    RE: TT .46 Pro w/ Perry VP30


    ORIGINAL: w8ye

    I would at least try the return system with the tee right next to the needle valve
    I was going to try it when I have time. I had to go out of town for the weekend but I'll hit the hobby shop on my ride back into town and grab a 3-way tee fitting to try.

    Thanks w8ye.
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  4. #4

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    RE: TT .46 Pro w/ Perry VP30

    This set-up ran great on the bench and in my plane...
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  5. #5
    Sport_Pilot's Avatar
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    RE: TT .46 Pro w/ Perry VP30

    As I recall the screw will back out 3/16" to 1/4". It should work if you back it out enough. I run it to full speed set the high speed needle so that it is running extra rich, then back the hex out till it starts to lean. From there you can usually adjust the needles normally.

    However from some of the discussions I suspect many of the Perry pumps have inop regulators out of the box. But the last one I had about a decade ago did not need a bypass on a 90 sized engine.
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  6. #6
    1QwkSport2.5r's Avatar
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    RE: TT .46 Pro w/ Perry VP30


    ORIGINAL: Sport_Pilot

    As I recall the screw will back out 3/16'' to 1/4''.* It should work if you back it out enough.* I run it to full speed set the high speed needle so that it is running extra rich, then back the hex out till it starts to lean.* From there you can usually adjust the needles normally.*

    However from some of the discussions I suspect many of the Perry pumps have inop regulators out of the box.* But the last one I had about a decade ago did not need a bypass on a 90 sized engine.*
    Well, my engine kept flooding to the point that I had to pull the plug and turn it over to clear it. I was turning the regulator screw in small 1/16 increments (Out) until the engine would run. The screw is backed out about twice as far as it was from the pkg. There is little tension on the regulator screw though it needs a little less pressure yet. Since it's a .46 and not a .90, I think it's gonna need a return line. I don't think a bypass loop is needed though. Anytime I got the engine to run and it quit, fuel dripped from the carb. Once I got the regulator to where it is now, I don't get much fuel dripping and the engine starts easier.
    GlowHead Brotherhood #3
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  7. #7
    1QwkSport2.5r's Avatar
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    RE: TT .46 Pro w/ Perry VP30

    I ran my TT .46 with the perry and a T fitting return line with decent results. I found the idle needle to still be rich, so leaning it down gave better throttle response though it still seemed to load up slightly. Typically I use 7-8 seconds at idle then WOT to set idle mixture for transition. The butter zone for this seemed more sensitive than unpumped and upright but nonetheless ran okay. I increased pump pressure and leaned the idle down to just rich of it cutting out when advancing the throttle and that seemed to be okay. It still loaded up slightly after 6-8 seconds and only quit 2-3 times advancing the throttle too fast.

    Question is ( I'll take a video later and post it showing what it does ) do I increase pump pressure further and keep leaning the idle needle down or will I just have a slightly rich transition until I get a pump carb? The engine turns up nicely but it loads up only slightly.
    GlowHead Brotherhood #3
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  8. #8
    Duplicate post
    Last edited by Jeremy_H; 09-26-2014 at 04:36 PM. Reason: Duplicate post

  9. #9
    I'm trying these pumps on my Twin, how did this pan out for you? There seems to be a lot of mixed reports out there.

  10. #10
    1QwkSport2.5r's Avatar
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    Quote Originally Posted by Jeremy_H View Post
    I'm trying these pumps on my Twin, how did this pan out for you? There seems to be a lot of mixed reports out there.
    Don't bother. Using a Perry pump on an engine without a pump carb is a major pain. Better off using a Cline of Iron Bay regulator in place of the pump. The Perry pump has a pressure regulator but what you really need is a demand regulator which is what the Cline and Iron Bay are. I don't believe the Iron Bay is made anymore though. My pump is in a box of junk, I'll probably never touch it again.
    GlowHead Brotherhood #3
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  11. #11

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    Get a OS F plug to try as this will help with the loading up at idle. Fist install the plug with out the copper gasket and then turn the engine over to see if it clears the piston. if it does which i think it will reinstall with the gasket. The F plug has a little step that helps keep it out of the fuel puddle.

    you can also run a little one ounce tank behind the engine. keep this inline with the carb. use the pump to keep that tank 1/2 - 3/4 full. this way the engine wont have to pull it very far and should run well this way.
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  12. #12
    1QwkSport2.5r's Avatar
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    Quote Originally Posted by airraptor View Post
    Get a OS F plug to try as this will help with the loading up at idle. Fist install the plug with out the copper gasket and then turn the engine over to see if it clears the piston. if it does which i think it will reinstall with the gasket. The F plug has a little step that helps keep it out of the fuel puddle.

    you can also run a little one ounce tank behind the engine. keep this inline with the carb. use the pump to keep that tank 1/2 - 3/4 full. this way the engine wont have to pull it very far and should run well this way.
    Aside from the glow plug, I tried the rest of it without good results. The header tank worked sort-of. The answer to my situation is a demand regulator and pressurized fuel tank or move the fuel tank higher. I opted to move the fuel tank. The engine would draw fuel from 8" away fine, I just had to run the idle speed faster and a richer idle mixture. The midrange was a little burbly but I was only using 5% nitro. The OS F plug is not the cure-all everyone thinks it is. I think it's an expensive mediocre performing plug. No offense.

    Without a pump carb, a Perry pump does not work on smaller engines for beans. A demand regulator and pressurized fuel tank is the answer if fuel draw is poor at the engine. But what do I know?
    GlowHead Brotherhood #3
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