banks 42747 Big Hoss, Owner'S Manual

Page: 8 / 13

8
96774 v.5.0
The layout for the drilled and
tapped holes on the machined
intake face is referenced from
the centerline of the front head
bolt and the head gasket surface
of the head.
Figure 3
shows the
locations of the upper and lower
bolt hole rows, as well as the
three (3) dowel pin holes.
IMPORTANT:
Note that all hole
centerlines are SQUARE TO THE
HEAD GASKET SURFACE of the
head. Not the angled surface that
was milled. It may be desirable to
mill a
1
⁄
4
inch diameter flat spot at
each hole location to prevent the
tapdrill from walking off center.
All but one of the upper row of
twelve
5
⁄
16
-18 tapped holes are
drilled and tapped through the
outer wall of the rocker cover
rail. The lower row of six 3 ⁄
8
-16
tapped holes must not exceed
the indicated tap drill depth to
prevent the holes from breaking
through into the water jackets.
Before drilling, verify that your
head has enough material to
accommodate the indicated tap
drill depth. These holes must be
bottom-tapped to provide the
proper bolt thread engagement.
The dowel pin holes may be
drilled or drilled undersize and
then reamed (this is the preferred
method). The dowel pins provide
alignment and allow the manifold
to expand with temperature
change while maintaining proper
top-to-bottom position.
-EnD, SEcTion 5-
No further machining operations
are required for manifold
installation however the milled
intake surface opening on
the head should be ground to
match the manifold opening
for optimum airflow. The milled
surface on the head should be
sprayed with layout dye and the
three (3) dowel pins supplied
tapped into place. Dowel pins
should protrude no further than
.200 above the milled surface.
Install the 0-ring in the grove on
the intake manifold flange face.
Take care that the 0-ring does
not get stretched or twisted.
coat the exposed surface of the
o-ring with enough white grease
so it will leave an imprint of
its position when bolted to the
cylinder head. Temporarily bolt
the manifold to the cylinder head
with 8-10 bolts (See
Figure 4
for
bolt locations), washers must be
in place on long bolts to draw
bolts against manifold.
Using a sharp scribe, reach
through the 4-inch diameter
hose inlet and scribe a line on
the head at the head-to-manifold
junction at all places where the
milled head surface hangs into
the manifold opening. A piece
of stiff welding rod ground to a
sharp point or a hook scribe may
be used to reach farther into
the manifold. Once the head has
been marked as far as possible
through the manifold opening,
remove the manifold from the
head and observe the o-ring
imprint on the head surface to
determine where you can safely
grind head material away near
the 0-ring grove.
We suggest you keep your
grinding no closer than .050
to the inner edge of the O-ring
grove. Pay particular attention to
the o-ring sealing at the upper
rear corner of the cylinder head
intake opening where the o-ring
has a very narrow sealing path.
The sharp tang which is left on
the outside of the head at the
rear may be cut off flush with the
rear of the intake manifold flange.
If additional cylinder head porting
and valve work is to be done, it
should be completed at this time.
once all headwork is completed,
the head may be cleaned,
reassembled, and reinstalled
on the engine per the service
manual reassembly procedure.
NOTE: Some cylinder head
gaskets have tabs, which extend
out from the head-to-block
junction on the intake side of
the engine. These tabs should
be bent down after the head is
installed to clear the bottom of
the intake manifold.
The three throttle control bosses
on the top/front of the intake
manifold may be cut off if
removal is required for a second
injection pump as part of a dual
pump kit. This modification
should be done prior to intake
manifold installation
-EnD, SEcTion 6-
Section 6
PORT MATCHING
Section 5
DRILLING AND TAPPING