Fp regulator mods

Greg Hermann bearbvd at sni.net
Mon Jan 11 22:27:00 GMT 1999


 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.

Hey--thanks for the part number. sounds like a deal!

>  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!

 --Carl had a hand in that TOO!!--THANKS!!

There are some 1:1 and 3:1 and 4:1 ratio pneumatic pressure corrected
pressure regulators available both for industrial steam line use and for
industrial (ammonia refrigerant) refrigeration systems.  I am SURE that
regulators intended for either of these applications would be appropriately
safe for fuel use! :-) But, none as good a deal as the Mallory unit! IMHO ,
Mallory makes FINE stuff!!

You can also easily do like Bell does with their rising rate unit, and use
a couple of orifices and a needle valve in the manifold pressure line to
the regulator so as to be able to fine tune the rate of rise once the
diaphragm sizes are close.

Another possibility, if you want REALLY accurate control, would be to
REDUCE the size of the port in the Mallory valve down to about .060"
diameter (with a bushing), get the control rate the way you want it as
discussed above, and then use the Mallory regulator as a PILOT valve to
operate an industrial grade control valve with a BALANCED port, and with
said port sized correctly for your particular flow situation!! Said
industrial valves in the size range we are talking about would prolly set
you back about one portrait of Ben (otherwise known as a "fun coupon"!!)
And you are talking about a truly bulletproof piece--good for ammonia, or
whatever, certainly OK for gasoline, and prolly literally able to make a
.38 Special slug bounce, if not a .357!!
>
Regards, Greg





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