I generally run an 18 psi primary and a 12psi secondary for 30 psi
    total. However the pressure never gets that high as the air spring
    accepts all the coolant expansion without reaching 30 psi.

    Dave Leonard


    --
    Dave Leonard
    Turbo Rotary RV-6 N4VY
    http://members.aol.com/_ht_a/rotaryroster/index.html
    http://members.aol.com/_ht_a/vp4skydoc/index.html


    I don't see how you figure they are in series Dave.
    When the first cap goes off the pressure in the second chamber
    will become 33.5 psi absolute immediately which will over power
    the 12 pound spring in the second cap. These caps operate
    on spring pressure. Here is a diagram.

    BTW do you have a 3 to 4 inch micrometer for measuring the rotor
    housings?

    Paul Lamar ...No rotor no motor.

------------------
Paul, I don't agree with your analysis of the radiator caps operation. Let's
take one cap, venting to atmosphere, The pressure in the system has to rise
enough to overcome the spring + the outside pressure of the atmosphere. So,
with a 10# cap, the pressure must raise to 25 psi (absolute) when you are at
sea level. As you go up in altitude, the *absolute* pressure will drop as
the atmospheric pressure drops.

Now, lets install a chamber with another (15# ) pressure cap. When the first
cap starts to relieve, it pressurizes the other chamber, and the back
pressure on the first cap rises.  So the *absolute* pressure in the engine
is = pressure in second chamber + pressure relief of first chamber. If
sufficient pressure is transferred into the second chamber, then the
*absolute* pressure in the engine is = atmospheric + pressure relief value
of second cap + pressure relief value of first cap.

All of this assumes that the flat rubber seal on the cap (that is loaded by
a flat disk spring) can withstand the cap pressures.


Bill Schertz
KIS Cruiser # 4045


Yes that is precisely the problem. I will build a test rig in a few days
and see how much pressure it will hold. These seals are not designed
for significant pressure.

Here is what the test rig  should look like.