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This is on a set of Delkron cases. |
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Few things to note here, I poked colored wire
in the drilled passages to show oil flow.
Red wires here are pressure from the pump to the tappet screen.
Oil enters the case from the pump and makes a right turn, then turns
again going up into the bottom of the tappet screen.
Yellow wires here are for oil that has passed through the tappet screen.
once oil has passed through the screen, it goes in two directions in
these cases.
It goes to the top end oiling fitting behind the rear tappet block to
feed the rocker shafts.
it also passed through a drilled hole headed for the tappets.
that allen head set screw above the pump and just below and behind the
tappet screen hole is where they drill from to start this passage.
That passage travels up at an angle through the right side of the case
and ends behind the top gear cover dowel pin.
That dowel pin hole is drilled deep enough to get the oil back to where
they drilled down from the tappet block gasket surface.
The red and yellow wire passages at gear cover surface are capped off by
the cover and gasket.
Black wire is for primary oiling from the breather gear port if used.
Blue wire is pinion shaft/rod roller oiling feed.
The basic way an 81 and up pump system works is... screened oil under
pressure feeds the tappets and the rockers.
This is where the system will have the oil pressure you would see on a
gauge or at the idiot light sending unit.
Once you have enough pump output to supply more than is needed for
pressure, the regulating plunger in the pump lifts up to un cover a
passage that leads to the pinion shaft for oiling the rod rollers.
There will not be much pressure at all in this passage, just flow.
some pinion shafts have an oil restrictor to limit flow to the crank
pin, some don't.
If pump out put is still more than what's needed to supply the top end
pressure and also the flow to the pinion the plunger will rise more yet
again to by pass oil back into the oil tank supply feed port inside the
pump.
That extra amount of oil will just pass through the pump and not enter
the gear case just to be pumped back to the tank.
That's the advantage with the 81 and up oil system.
With 80 and older engines, they all dump that extra pressure and flow
into the gear case.
That extra oil makes the return section of a pump work harder than it
needs to.
Where was I... oh...
Here is a pic of the different pump gaskets: |
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81-91 on the left, 68-80 on the right.
Note the extra hole in the 81 and up gasket.
That extra hole is what you need to drill for in your cases... |
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I use an S&S drill guide for this, it's a
no brainer this way.
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Do you need to use a drill guide? Not really.
You could locate the hole you need to drill and start it with a center
drill into the case.
once you have a start on the hole you could angle the drill bit and free
hand drill the hole.
the main thing to keep in mind here is to not drill into any other oil
passages.
This is what the finished hole looks like from the pump side...
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| And from inside the gear case... |
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That hole is used for a vent passage above the
pressure regulator valve in the pump.
without that hole the regulator plunger in the 81 and later pump will
hydraulic lock and the oil pressure will not be controlled by the spring
above the plunger.
It's simply there just to vent any trapped oil above the regulator
plunger. |
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