I was hoping that chucks comment about oil restrictors would die fast, but
these off the cuff comments while partially true, sometimes take the form of
truth and fact very quickly. We need to talk about this aspect of the olds
455 and put the issue of oil restrictors and other modifications in its true
perspective before to much money is spent and people start losing engines.
Fact: You cannot install the oil restricters and keep the stock stamped
rockers. You have to install roller rockers
Fact: Installing restricters and HV oil pumps does not accomplish what you
think it does. Read this:
HV oil pumps do pump more per/rpm than the standard volume oil pumps, but
what some forget is that the
pressure relief valve pops open at a set pressure, directing all the
excess oil back into the oil pan before it goes
up to the top of the block. Since the oil passages remain a constant
diameter, you are pumping exactly the
same amount of 55psi oil at 4000rpm using a HV pump as you are using a
standard pump; the pressure relief
valve is just allowing more of the HV's output to go back into the pan.
I suppose that in theory, the pressure relief might not be able to keep
up with the extra output of the HV pump,
but you would know this when you saw the oil pressure climbing at high
revs beyond what the pressure relief
valve spring is rated at (if you don't know what that is, you can
figure it out once you run your engine much
above idle, as a HV pump will "max out" rather quickly at a certain psi
and stay there no matter how much you
rev your engine- for example, my 403's HV pump hits 55psi by about
2000rpm and stays there, no matter
what I rev it to). In that case, you would need some reserve oil,
because the drainbacks in the heads would be
the bottleneck for the extra oil going through the lifters (which are
kind of "oil pumps" themselves).
As for the oil restrictors, they only restrict flow to the cam bearings
(refer to a diagram of the Olds V-8 oiling
system to confirm this one), not to the lifters or the pushrods or the
upper end of the engine. A reversible way
of achieving the same thing is to drill a smaller hole in your cam
bearings, and install that hole facing the oil
feed hole from the main journals. To restrict flow to the upper-end of
the engine, you need restricted
pushrods.
Now, the thing you might want to be concerned about is the oil foaming,
since the oil pressure relief valve is
just SPRAYING the oil back into the pan, and at a high rate at high
rpm's, you could have your oil pickup
sucking oil bubbles. Not good.
Consider this: you can have a high-capacity oil pan in a couple days
via mail-order for about $200, including
the extended pickup. How much have you already sunk into the motor? Is
it worth the extra peace of mind to
have a couple extra quarts of oil on hand to feed your engine? Then
again, unless you start running this engine
at a constant 4000rpm, you really won't encounter this problem. This is
your call.
haven't got time right now to answer more but have much more information on
other mods for the 455 olds engine.
>Chuck
>I've asked this question before but can't locate the answer.....does
>the same apply for the 403 or is this just a 455 thing...
>
>Mike Beaton Antigonish NS 403 Kingsley
>Looking for info on How To File Messages
>
>> The oil restrictors are installed at the lower end of the motor so the
>> oil will or can not be pumped up into the top of the engine so fast. It
>> is important to keep the oil in the lower end (bearings). If this is not
>> accomplished during the engine rebuild when you get the GMC out on the
>> highway after break-in in etc. You will find that driving 65 and up you
>> will have al the oil pumped into the top end, Rocker Covers will be
>> full. This is not where you end immediate lubrication if you slow down
>> or even have to come to a stop and go situation. What will happen is the
>> engine will continue to turn without I repeat without the proper
>> lubrication and you will score your main bearings. This makes a loud
>> noise that you will certainly notice. I am deaf and I can hear it. When
>> you hear it, it is to late the damage is done! Joe Mondelo discuses this
>> in his engine rebuilding in the GMCMM magazine. Chuck Lompoc
>>
>
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
"The beautiful Mohawk Vally"
