Gentlemen,
As Dick has suggested, the relief valve is used to keep the system from
being over pressurized. Of course, the purpose of the pump is to provide
flow, regardless of the pressure required. The pressure relief valve is
analogous to a voltage regulator, voltage being required to cause current to
flow. More pressure (or voltage) is not better by and of itself. Most
often, the reverse is true.
Regarding the oil system, if an increase of pressure is suddenly required to
get the proper amount of flow, then there is a restriction in the system
causing the need for that increased pressure. In other words, something is
wrong and needs attention. Raising the systems pressure would likely be an
ineffective band-aid, largely because an oil system tends to be comprised of
a number of parallel pathways. Triumph most certainly matched the oil
pump's flow-curve to match the resistance to flow inherent in the system.
In an overpressure situation, the pump would probably fair well as most pump
designs allow for valving of the output without a problem. To elaborate on
what Dick said, once the viscosity of oil is thinned due to coming up to
operating temperature, the oil's inherent resistance to flow is so
drastically reduced (due to it's reduced viscosity) that the pressure in the
system is no longer as high as the relief valve set-point, so the valve is
out of the picture altogether in that operating condition.
Since the purpose of an oil pump is to cause the flow of oil to engine
components, it is interesting to me to note that a pressure gauge (not a
flow meter) is commonly used. I never thought about it before. My guess is
that a pressure sensor is cheaper to make and would most likely function
properly over a longer period of time than a flow meter. A flow meter
manufactured in the days of our 6's would have most likely used a small
paddlewheel to drive a generator in order to cause the meter needle to move.
These types of sensors are much more expensive than a spring loaded wiper
and resistor, or whatever like component the 6 uses.
Gary
'73
----- Original Message -----
From: "Sally or Dick Taylor" <tr6taylor@webtv.net>
To: "Douglas Morris" <dcmdcm@earthlink.net>
Cc: <6pack@autox.team.net>
Sent: Thursday, September 18, 2003 10:52 PM
Subject: Re: Oil Pressure Relief Valve, Heavier Spring Useful?
> DougM---It's my opinion that a heavier spring does nothing to raise
> pressure when the oil is hot. A stouter spring will delay the bi-pass
> from opening when the oil is cold and the pressure is already high, but
> who needs this pressure then?
>
> I would imagine some harm could come from pressure going too high (over
> 100psi)? We know the oil pump driver will try to turn the pump, & the
> pump will try to do its job. Don't know what would be the first part to
> fail. If you decide to go with the heavy spring (or shim the one you
> have) keep an eye on the pressure gauge while accelerating a cold
> engine.
>
> Dick
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