Milodon 4 Bolt Main Caps - with Angle Side Bolts - Manual

MILODON
2250 Agate Court
Simi Valley, Ca 93065
(805) 577-5950
ANGLED SIDE BOLT MAIN CAP
INSTALLATION INSTRUCTIONS
Congratulations, you have purchased the highest quality 4-bolt performance main caps
available. The tensile strength of the ductile iron that Milodon uses in these main caps is 85,000
PSI. This is considerably stronger than other mild steel “Billet Caps". Also the expansion rate
of ductile iron is equal to that of the cylinder block, eliminating engine bearing failure due to
irregular bearing bore expansion when the engine reaches operating temperature.
In addition to being precision machined, this design uses the superior angled side bolt
configuration. It is this feature that makes them vastly more desirable than the stock 4-bolt cap or
even other aftermarket, stock designed 4-bolt pattern main caps. The side bolts pull from the
side wall of the block and not the flimsy main web area. The entire saddle area is supported
more firmly and the register, that locates the cap, is preloaded to stop any cap movement. In
blown, nitrous and other high power applications this becomes extremely important. In a test we
ran on a Big Block Chevy Pro Stock engine, there was an increase of 1 MPH through the lights
by just installing a set of Milodon main caps!
Before beginning your installation check the parts list. Milodon supplies complete bolt
kits with all main cap sets. However, if maximum strength and durability are required, studs
should be used. Studs are available for all applications, refer to the Milodon catalog for specific
part numbers.
Your Main Cap Kit includes: 3 - Center main caps (#2, #3, #4)
6 - Center main bolts & washers
6 - Outer main bolts & washers
1 - Drill Bushing
STEP 1 Measure #2, #3 and #4 cap registers in the block to determine if registers are equal. If
not, the registers must be squared by milling. Take the largest reading of the six
registers (both sides of three mains) and mill the other registers, at the portion in the
block where the bolts holes are located, down to this measurement. Now that the
block registers are equal, to get your necessary register depth for the main cap, take
the register depth measurement in the block and add the .001 to .003 required side
bolt pad clearance. Mill the cap to yield this dimension. If the clearance dimension is
too large then mill the cap register on the bolt hole pad. If the dimension is too small
then mill the outer most pad taking great care not to kiss the vertical register step.
STEP 2 Main caps should be milled so register depth is .001-.003 more than block register
depth. This allows .001-.003 clearance between cap and block when the center bolts
are torqued down. This clearance is critical, as it is this small air gap that gives the
cap its bite on the register and thus stops the cap walk. Clearance in excess of .003"