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Re: "real" oil pressure readings

To: cak@dimebank.com (Chris Kantarjiev), british-cars@Autox.Team.Net,
Subject: Re: "real" oil pressure readings
From: Ray McCrary <spook01@mindspring.com>
Date: Sat, 19 Sep 1998 22:35:54 -0500
Hi Chris,

It occurs to me that even if you 'read' the bearing pressure, it may be
useless knowledge.  

The book pressure relies on pressure obtained at the rear of the block.

Remember that too much pressure = too much heat, as well.

You can actually destroy your bearing with excessive pressure.

Just something to think about.

Regards,

Ray      

At 01:48 PM 9/16/98 -0700, Chris Kantarjiev wrote:
>In our stable is a Morris Minor with an overbored (to 1380cc) A series
>engine from an early 70's Spridget (according to the serial number). We
>have installed an oil pressure gauge in the dash, since I'm paranoid
>about idiot lights.
>
>I recently added an oil cooler, with thermostat. Now, I don't really
>trust the oil pressure readings ... they read higher than before, even
>when cold. I know why: the oil pressure line taps in to the gallery
>that leads from the oil pump to the large exit fitting at the rear  of
>the block. In a "normal" engine, this goes through a metal fitting
>direct to the filter head, whence the oil goes to the bearings and
>elsewhere. The oil filter is probably a 10-15 psi drop in pressure.
>
>Now, with a thermostat, an oil cooler, some hose, and some 45 and 90
>degree fittings, there's more backpressure before hitting the bearings,
>so the pressure near the pump is higher, yielding higher dash readings.
>But likely lower pressure at the bearings, where it matters.
>
>I really want to measure the pressure at the filter head, preferably
>after the filter - I want to see what the bearings see. It appears that
>it would be easy to drill the (spin-on) filter head between the two
>long mounting bolts and tap it for a 1/8 NPT fitting.
>
>Has anyone done this? I don't want to start drilling and find that
>there isn't enough meat to take the fitting. The idea would be the face
>where the bolt heads sit, but I'd also be happy with the fitting coming
>out the top (sort of straight through where the threaded boss for the
>filter is).
>

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