Fp regulator mods

[Clarence Wood]

  Mike, I don't know what your budget is for this project but I have, on occasion had to make modifications under budget restraints.  In every case, I had to re-due the work because the material I had to work with could not handle the load.  I would like to recommend an alternative:  Mallory has a return type BDFPR (Boost Dependent Fuel Pressure Regulator) made out of billet aluminum for $69.95 (JEGS part # 650-4309).  The unit will still work if your engine is not a turbo.  It uses 4 set screws to hold the diaphragm and it is adjustable.  You could modify this unit, successfully, without the worry of material failure.  Remember that you are dealing with fuel: a sudden leak can cause tremendous damage!  This Mallory unit is the cheapest one that I have found that has the ability to be modified.  It is a three port unit (actually it has 4 port openings but is called a 3 port).  It comes with an assortment  of springs: 3-12 psi, 10-40 psi, 35-65 psi.  The vacuum index decreases !
about 1 psi for every 2 inches Hg; the boost index increases 1 psi for every 1 psi of boost.
  Now, with this unit you could easily install two diaphragms.  You could reduce the area of one by using two large washers, one on top and one on the bottom of the diaphragm, that extended into the chamber restricting the area of the diaphragm (washers with a smaller inside diameter than the original unit) and to hold the original diaphragm.  Drill the holes and get longer set screws.  By ordering a replacement diaphragm you could connect it to the first diaphragm, and by inserting a spacer, after drilling a hole to vent to the atmosphere, you would have the unit that Greg described.  The spacer would have to be made but could be done with non specialized tools.
  I have one and am going to increase the boost index to 6:1 via the method described above.
  Oh, THANKS GREG, for telling me how it has to be done!  
  


At 09:14 AM 1/11/99 -0500, you wrote:
>>might be easier to just vent the manifold side of the existing 
>>one to atmosphere, and add a second, bigger one with 
>>manifold pressure on one side and atm.
>
>Greg,
>
>I didn't pay this much attention at first, because it seemed 
>beyond my capabilities.  Mostly because manufacturing a 
>diaphram with the spring seat, etc would be impossible for 
>me.  But the more I think about it, the more I like the idea.
>
>Maybe I can find an existing larger diaphram from a larger 
>regulator, or and EGR valve, or a A/C vent mechanism, or 
>cruise control, etc.  (Any other ideas?)  I would need one with 
>a diameter of ~2" to achieve the desired rising rate.
>
>Connecting the new top to the old bottom will be tricky part.
>
>After my post last night about adding a larger diameter pipe 
>to the outlet side of the reg., it later occured to me that it may 
>not work either since, once the diaphram lifts to relieve pressure, 
>the entire underside of the diaphram will be exposed to the fuel 
>pressure.
>
>Anyone have a cheap milling lathe for sale? 8-)
>
>Thanks,
>-Mike
>==========================================
>Mike Pitts
>Delray Beach, FL
>mpitts at emi.net
>==========================================
>
>
>