Received-SPF: pass
 receiver=logan.com; client-ip=209.85.218.226; envelope-from=lehanover@gmail.com
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=mime-version:date:message-id:subject:from:to:content-type;
        b=ZtCD2kEW/Rj2UgI8Afuak3sa84PRN6xLdQDdXL223CGF8EX3jqJUZRIn/koNrlpPSc
         Do3v3EXfKRXqnTTlRTXEyykMMkeEd7gVAxsyKI36U337I5ObRfbSnWxHJ9MxluYcDyct
         DGNlHq47fw2dA/fw3SmzTaPJOzLdVT3KWs61I=
MIME-Version: 1.0
Date: Sun, 11 Apr 2010 01:39:54 -0400
Message-ID: <i2q1ab24f411004102239kf8e910f6xae99f9e11a56c9f4@mail.gmail.com>
Subject: Fuel pressure for Webers
From: Lynn Hanover <lehanover@gmail.com>
To: flyrotary@lancaironline.net
Content-Type: multipart/alternative; boundary=0015175884b643dffe0483ef7542

--0015175884b643dffe0483ef7542
Content-Type: text/plain; charset=ISO-8859-1

Typical fuel pressures would be 2 1/2 to 3 1/2 pounds at the carb inlet. A
fuel pressure isolator can be used to carry fuel pressure to a gage in the
cabin. So the gage is powered by a few table spoons full of antifreeze,
should a gage fail. Or an electric gage.

Racers use these carbs well above their design flow rates. It is a common
problem to find that the fuel flow is so high that the little filter element
under the brass nut adjacent to the fuel inlet banjo fitting has become the
main jet. It is also so fine a mesh that anything in the fuel will plug it
up. Remove and discard this filter. Install a big in line disposable filter
can next to the carb or at least close by. The fitting out of this filter
can have a Tee fitting to provide a fuel pressure reading. The gage should
be in the leg of the Tee not the run.

I run two Carter 7 PSI rotary vane pumps in Parallel to maintain 6 PSI at
the end of the longest straightaway. Great pumps. Last 3 years in a a racer.
I give them away when the output drops to 6 PSI.

This pump puts out a bunch of fuel. It is internally regulated, but I
regulate it to 6 PSI right at the carb.
 We use just one pump until on the pace lap and well up to speed. Then
switch on the second pump.

Pumps in Parallel double volume capacity. Pumps in series will double the
pressure.

The downside of a positive displacement pump is that you cannot suck fuel
through them or blow fuel through them. So a back up pump needs to be in
parallel with the main pump.

I suspect that the gravity feed provides enough fuel for the RPM max you
have now but there is little to no fuel level in the bowl to support the
boosters (auxiliary venturis). The idle jets and transition circuit is a few
small holes right beside the down side of the butterfly.

With the pump turned on for a few seconds let the fuel pressure come up to 3
pounds minimum. Shut off everything. Take the bowl cover off. Look at the
fuel level, with the float pushed down to the correct height. Or just forget
it if you get the revs you need with the prop back on it.

Do not use the old style timing light. If you have stents or a pace maker or
a defibrilator you can kill yourself with it. Inductive only. Try flipping
the pickup over to reverse the polarity. If that doesn't work reverse the
two leading wires. They both fire at the same time anyway so where the
pickup is attached is of no importance.

The trailing plugs are distributed. They cannot be fired at the same time
because one or the other will have an apex seal between the plugs exposing
the next fuel charge to the spark 100 degrees too soon.

For years the stock maximum oil pressure in every Mazda rotary was 71 PSI.
Probably checked at 3,000 RPM. The shop manual would have the exact
measurement. For an unloaded engine very little pressure is required. The
bearings are well oversized for the stress involved. By 3,500 RPM you should
have at least 71 PSI. In the racer I run 100 PSI. The FD twin turbo runs 115
pounds, and the Renesis has over 100 PSI at it turns up to 9,000 RPM. Not
required in an airplane. The oil pressure relief valve is in the bottom of
the rear iron. You can change it out for a different model with the oil pan
off. Later pieces are welded shut, and difficult to alter. Early pieces in
the RX-2 RX-3 and RX-4 can be disassembled and washers installed to give any
pressure you like. I would like 80 PSI at full tilt. We raced on that for
years and never lost a bearing. But 71 is fine since the airplane use is far
below the stress of even hard street use. You could install the later relief
valve but the added pressure is not needed and the pump will wear out
sooner.

Not to worry.

Lynn E. Hanover

--0015175884b643dffe0483ef7542
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

<div>Typical fuel pressures would be 2 1/2 to 3 1/2 pounds at the carb inle=
t. A fuel pressure isolator can be used to carry fuel pressure to a gage in=
 the cabin. So the gage is powered by a few table spoons full of antifreeze=
, should a gage fail. Or an electric gage.</div>

<div>=A0</div>
<div>Racers use these carbs well above their design flow rates. It is a com=
mon problem to find that the fuel flow is so high that the little filter el=
ement under the brass nut adjacent to the fuel inlet banjo fitting has beco=
me the main jet. It is also so fine a mesh that anything in the fuel will p=
lug it up. Remove and discard this filter. Install a big in line disposable=
 filter can next to the carb or at least close by. The fitting out of this =
filter can have a Tee fitting to provide a fuel pressure reading. The gage =
should be in the leg of the Tee not the run.</div>

<div>=A0</div>
<div>I run two Carter 7 PSI rotary vane pumps in Parallel to maintain 6 PSI=
 at the end of the longest straightaway. Great pumps. Last 3 years in a a r=
acer. I give them away when the output drops to 6 PSI.=A0</div>
<div>=A0</div>
<div>This pump puts out a bunch of fuel. It is internally regulated, but I =
regulate it to 6 PSI right at the carb.</div>
<div>=A0We use just one pump until on the pace lap and well up to speed. Th=
en switch on the second pump.</div>
<div>=A0</div>
<div>Pumps in Parallel double volume capacity. Pumps in series will double =
the pressure.=A0</div>
<div>=A0</div>
<div>The downside of a positive displacement pump=A0is that you cannot suck=
 fuel through them or blow fuel through them. So a back up pump needs to be=
 in parallel with the main pump. </div>
<div>=A0</div>
<div>I suspect that the gravity feed provides enough fuel for the RPM max y=
ou have now but there is little to no fuel level in the bowl to support the=
 boosters (auxiliary venturis). The idle jets and transition circuit is a f=
ew small holes right beside the down side of the butterfly. </div>

<div>=A0</div>
<div>With the pump turned on for a few seconds let the fuel pressure come u=
p to 3 pounds minimum. Shut off everything. Take the bowl cover off. Look a=
t the fuel level, with the float pushed down to the correct height. Or just=
 forget it if you get the revs you need with the prop back on it. </div>

<div>=A0</div>
<div>Do not use the old style timing light. If you have stents or a pace ma=
ker or a defibrilator you can kill yourself with it. Inductive only. Try fl=
ipping the pickup over to reverse the polarity. If that doesn&#39;t work re=
verse the two leading wires. They both fire at the same time anyway so wher=
e the pickup is attached is of no importance. </div>

<div>=A0</div>
<div>The trailing plugs are distributed. They cannot be fired at the same t=
ime because one or the other will have an apex seal between the plugs expos=
ing the next fuel charge to the spark=A0100 degrees too soon. </div>
<div>=A0</div>
<div>For years the stock maximum oil pressure in every Mazda rotary was 71 =
PSI. Probably checked at 3,000 RPM. The shop manual would have the exact me=
asurement. For an unloaded engine very little pressure is required. The bea=
rings are well oversized for the stress involved. By 3,500 RPM you should h=
ave at least 71 PSI. In the racer I run 100 PSI. The FD twin turbo runs 115=
 pounds, and the Renesis has over 100 PSI at it turns up to 9,000 RPM. Not =
required in an airplane. The oil pressure relief valve is in the bottom of =
the rear iron. You can change it out for a different model with the oil pan=
 off. Later pieces are welded shut, and difficult to alter. Early pieces in=
 the RX-2 RX-3 and RX-4 can be disassembled and washers installed to give a=
ny pressure you like. I would like 80 PSI at full tilt. We raced on that fo=
r years and never lost a bearing. But 71 is fine since the airplane use is =
far below the stress of even hard street use. You could install the later r=
elief valve but the added pressure is not needed and the pump will wear out=
 sooner.</div>

<div>=A0</div>
<div>Not to worry.</div>
<div>=A0</div>
<div>Lynn E. Hanover=A0</div>
<div>=A0</div>
<div>=A0</div>
<div>=A0=A0=A0</div>

--0015175884b643dffe0483ef7542--