If you were using very heavy race oil, like straight 50 sae or possibly 40
sae, and it was very cold in the early morning when the engine was first
started, the pressure drop accross the oil filter element might be so high
that the filter could collapse or ortherwise fail. You want the filter to
bypass under conditions like this. Once the oil is over 140 degrees or so,
we want all of the oil to be filtered. Increasing the spring pressure might
be a better idea. I so know the blocking the by-pass so it will not ever
open is something that is done on engish ford engines, but they typically
run maximum oil pressures around 60 psi. while on my "tractor engines" we
usually run maximum pressures around 90 psi.
----- Original Message -----
From: "Jack W. Drews" <email@example.com>
Sent: Wednesday, November 29, 2006 6:03 PM
Subject: [FOT] blow-ups
>I spent an interesting hour tracing out the path in the filter head,
>figured out the answer to the question, and got several replies that were
>either right on or close to it. Plus a couple of guys who figured it out
>previously and have found fixes.
> What I found was that the adjustable valve, when opened by the oil
> pressure, dumps oil back into the sump, as we know. It also has a spring
> that is quite stiff.
> The non-adjustable valve is fed by the same oil that the adjustable one is
> fed, but when opened it sends oil to the gallery. It has spring that is
> quite weak.
> My conclusion is that the non-adjustable valve opens first, sending oil to
> the gallery. In fact, judging from how really weak its spring is, it is
> probably always open. This means that our oil filtering system is not a
> full flow system that makes all the oil flow through the filter, but
> rather it is a bypass system, which always allows oil to bypass the filter
> and go to the gallery.
> Kudos to Greg Solow, Ken Gillanders, and Walt Emery who had this whole
> schmeer figured out and have found ways to decrease or eliminate the
> bypass feature. I'm going to do that too.
> Have any of the three of you seen any downside to simply replacing that
> bypass valve with a plug?
> uncle jack
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