Geoff Healey wrote an awesome article on oil pressure in one of the chatters
Years ago... Basicly he said that the oil pressure releif valve was an
indicator of engine wear on a long term basis..... when an engine is new the
oil would start bypassing at a lower Rpm .... when the bearings started to
wear they would allow more oil to escape and the amount of oil the Pump had
to supply was greater and would require a Higher Rpm to bypass......So one
could reference the point at which the oil actually started to bypass by
watching the gage and the RPM.... made sense to me.
The .001 bearing clearance with a new oil pump would give you ugly pressures
like your 80 and 48 at idle..... Believe it or not I think that is Way to
high.... The oil is so restricted that it builds up huge pressure and
doesn't flow away from the bearings so it's now stopped there and not doing
it's job which is to flow away and take heat with it.... now if you tell me
that you have .0025- .003 clearance and a High Performance Oil Pump I'd say
the pressure is moving the oil away Too Fast and again not taking the heat
with it.... 50-60 psi and 30 at idle is what I shoot for with the bypass
starting as early as I can get it.....
Keep in mind I don't know squat about these engines.... I have only rebuilt
about 3 of them and my Hundred engine.... 20 yrs ago.... ( none have failed
thank god ) but I am just sharing what little bit of the theory that I shoot
for when doing one.... With the Race motors I run on the salt flats I have
an adjustable Dry Sump oil pump.... I adjust them to higher levels because I
want the oil to flow away that fast.... as a matter of fact I have to
preheat the oil and the block just to start the Rodeck engine as it's
bearing clearances are to close cold.... the block grows substantially....
even Valve adjustments are off by .010 with the motor cold.... Bending a
titanium valve is a rather costly moment so there isn't any rev'ing the
motor until it's got Big heat in it anyway....
Keith
----- Original Message -----
From "Gerard Chateauvieux" <pixelsmith at gerardsgarage.com>
To: <SDOliner@aol.com>; <kturk@ala.net>; <spridgets@autox.team.net>
Sent: Sunday, September 16, 2001 11:16 PM
Subject: Re: bearing clearances, tappets and stuff
> David,
>
> You should be using assembly lube for the bearings and lifters and high
> friction parts. Sta-Lube makes an assembly lube with moly-graphite that
> works great. Spray the camshaft with dry graphite film and let dry before
> assembling, but use assembly lube on it too. the cylinders only need
> regular motor oil, whatever grade you plan to use. Make sure you rotate
the
> rings into proper position before assembling. If I remember correctly, my
> machinist recommended the compression rings be 180 degrees apart and with
> the gap facing the front/rear orientation. On the (3 piece) oil ring, I
set
> the mark on the center ring over the wrist pin, and the above and below
> ring on either side of the wrist pin. The rings will move, but that's
where
> he suggested I start them off.
>
> It was also recommended to me by Greg Schulz (Thicko list) to break in the
> cam in the following fashion (which I did)
>
> >When you finally fire that thing up for the 1st time, tho, get the
> >rpm up to 2500 and KEEP IT there for 15-20 minutes for proper cam
> >break-in. Never let a new cam idle during first startup. You want
> >to continuously flood the cam, lifters, etc with hi-pressure oil
> >after the first startup to prevent any cam/lifter scuffing.
> >
>
> The 1275 I just put together has 80lbs oil pressure on startup and at
> speed, and it idles at about 48 lbs warm. Engine temp runs at 170 to 180
> degrees.
>
> Gerard
>
>
> >Getting back to the rebuild. Does using STP and Oil an OK way to prelube
> >everything, except the cylinder walls?
> >
>
> --
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>
>
> G G Gerard Chateauvieux
> E A
> R R pixelsmith@gerardsgarage.com
> A A
> R G Pixelsmith on Duty
> D E
> S http://www.gerardsgarage.com
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