Oil flows from the oil pump into the block via the oil pump pad. This
pad has a 1/2-inch oil gallery on the production blocks and may be opened to 9/16-inch so as to match the exit
gallery on the Stage 1 & Stage 2 oil pumps.
OEM Oil Pump Pad, .500" Diameter:
Increase from 1/2-inch to 9/16-inch.
Modified Oil Pump Pad, .5625" Diameter:
Note in the above photos that the gallery entrance at the oil pump pad is not true center, and some pump mount gaskets
fit only one way. Also, if using an oil pump mounting gasket remember to open its diameter to 9/16-inch also.
(Below) Blend a radius into the hard corner.
Radius The Short Turn:
Oil flows from the pump pad through the block and into the outer perimeter of the
filter. The gallery that leaves the oil pump and enters the filter may also be carefully opened to 9/16-inch so
as to make this gallery's ID continuous from the pump to the exit into the filter pad.
OEM Filter Pad Entry, .500" Diameter:
While drilling this gallery oversize, occasionally stop and inspect the ID of the gallery and use the step
of the oversize bore as a visual aid to confirm that you are staying centered in the gallery and not offset drilling (and
risk breaking through).
Modified Filter Pad Entry, .5625" Diameter:
Radiussing/Blending The Hard Corners Into The Filter Pad:
And if you want to go further, radius the exit behind the filter thread boss.
Radiussed Filter Pad Center/Exit Gallery:
This last modification (below) to the filter thread adaptor may be performed under the most extreme racing circumstances.
Please note that this modification must be performed only on the thread adaptor with the wrench flats on the exterior (never
on the round exterior thread adaptor), and that even when using the correct adaptor (with the wrench flats), the
part is effectively weakened.
In the two photos below, the part on the left is as manufactured and
has a 0.500" ID. The part on the right is opened to 0.5625" (9/16") with a mill. This leaves about ~ .060" wall
between the ID of the part and the and the minor thread diameter, and should be strong enough to sustain the load
of the filter being threaded onto it:
Once the ID is opened up, the part is then placed into the jaws of a lathe and the exit-side is radiussed:
The modifications shown to the fitting(s) pictured directly above are for max effort application
The wrench flats allow torquing of the fitting back into the block while loading the thick end of the filter boss,
the small threads that the filter screws onto (as would be loaded with the version without the wrench flats...and
immediately twist apart).