[NSRCA-discussion] o.s. 1.60 backplate fuel pump ?

[mark hunt]

Lance,

I agree that the OS160 carb was not designed for positive pressure fuel supply...that may be why so many with the perry setup have to screw the low end all the way in and end up with the high needle at only 1 to 1-1/2 turns out.  Recently however, I have tried the perry setup using an overflow back to the tank.  This is simply a tee in the line between the pump and the needle valve that feeds back to the tank.  Any more fuel than the carb asks for now goes back to the tank....sort of like a regulator rather than a pump (iron bay?).  My high needle is now at 2 turns out and the low needle is at the factory setting....plus the mid range is not indicating any rich tendencies.  We'll see how it holds up over time...for now it's good.

-mark
  ----- Original Message ----- 
  From: Lance Van Nostrand 
  To: NSRCA Mailing List 
  Sent: Saturday, November 04, 2006 6:07 PM
  Subject: Re: [NSRCA-discussion] o.s. 1.60 backplate fuel pump ?


  Jon,
  I first saw a built in pump overheat on a Webra 145 in Lubbock (3000ft) on a 104 degree day.  After that I convinced the Mintor folks to install a nylon isolator/insulator.  They eventually got it done right (their first attempt leaked) and sent me test results of the engine running in 160 degree ambient.  My concern with the perrys is that they seem to work for a while, then need adjustment.  now I know there are probably a lot that have found them rock solid, but my observations are otherwise.  I know several that have had much better luck placing the tank on the firewall and eliminating the pump for the 160.  in my observations, if I were to use a 160, this is what I'd do.  The 160 was not really designed for a pump and has a small venturi with a lot of suction and doesn't need a pump.  Engines designed with a pump in mind might not be able to get away without one.
  --Lance

    ----- Original Message ----- 
    From: JonLowe at aol.com 
    To: nsrca-discussion at lists.nsrca.org 
    Sent: Saturday, November 04, 2006 11:49 AM
    Subject: Re: [NSRCA-discussion] o.s. 1.60 backplate fuel pump ?


    In a message dated 11/4/2006 1:01:33 AM Central Standard Time, toneuf at sbcglobal.net writes:
      Guys,
                  OK,   I got into this discussion late... 
             I am trying to locate a backplate
             fuel pump unit for my O.S.  1.60  FX engine.
             I read the infomation by Tom Koenig from last year, but still need the
             unit contact information.
             Does this unit acutally exist ?
             Maybe someone out there has a unit to sell?
             If not, can you  give me the forward  to this unit ?
             Austrialia?   Sheesh....
                Regards,  Robert Hixson    San Francisco
    When I first heard about people doing this, I thought it was really neat.  Now, after thinking about it, I can't recommend doing this.  Many engines with backplate pumps have problems with the pumps overheating, and vaporlocking or deteriorating.  I've seen this on Webras and Mintors, and watched the owners go to external Perry pumps.  Having the pump separate keeps its temp closer to ambient.  Plus, you can go to almost any hobby shop in the country, and buy a Perry pump off the rack for $30, and not worry about having a hard to find spare in an emergency.  You can change it out without removing the engine if you suspect a problem.  Todays widebody pattern ships have plenty of room in the nose, so mounting it is not an issue.  In addition, a separately mounted pump makes it much easier to adjust pressure as you are setting it up, and it isn't subjected to all of the vibration of the engine.

    Just my opinion.

    Jon Lowe



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