MAIN CAPS


These aftermarket main caps will strengthen not only factory 2 bolt blocks, but also 4 bolts. Unlike the factory caps, these not only have more cross sectional strength, but the real secret is in the angled side bolts!


The side bolts are angled so they pull from the side walls of the block and not the flimsy main web area. A bolt that is angled will require a massive amount of additional load to flex or stretch, let alone break. The side bolts heavily load the cap against the register step, which stops "cap walk". It is cap walk that causes a great amount of unforeseen bearing damage and horsepower loss.


Milodon main caps are CNC machined from high strength ductile material, which has the proper balance of strength yet is not too rigid that allows the transfer of increased shock loads to the crank and bearings. In this case, more is not better when it comes to hardness.


Only .030" of material removal is required upon initial installation, which will allow 100% cleanup on a damaged or crooked block. The drill bushing used to drill and tap the side bolt holes is included in the kit. The side bolts can be installed by anyone with a hand drill and a tap. If the block has square main registers, the block needs only a standard align bore to finish the job. Milling the mains is only necessary if the main registers are not square.


All necessary bolts, washers and the drill bushing are included in the center three cap kit. For maximum strength the installation of Milodon main studs are highly recommended.

Main Cap Facts:

While mild steel main caps may look like main caps and are economical, they are the wrong material for a performance application. True "deductile" iron caps take a beating and return to their original shape (deductile) saving the bearings and continuing to perform well. Very rigid mild steel caps act differently and do not absorb the impact from the crank and usually pound out the bearings if run hard. Its like if you had to jump out of a second story window. Would you go for the cement or the grass ? Your crank is thinking the same thing !

Deductile iron caps also cut better during align bore. They heat and expand at the same rate the block material does so the crank bore stays round instead of going oval. These are good things and probably answer the question of: "Why are these caps way less than the price of the Milodon caps ?"

SMALL BLOCK CHEVY MAIN CAP # STUD KIT #
w/o windage tray
STUD KIT #
with windage tray
             
283-327 Journal (Angled Bolts) 11050 81128 81129
283-327 Journal, Front Cap, 2 Bolt 11053
350 Journal, Factory 2 Bolt (Angled Bolts)1 11150 81128 81129
350 Journal, Front Cap, 2 Bolt 11153
350 Journal, Factory 4 Bolt (Angled Bolts)2 11160 81128 81129
350 Journal, Factory 4 Bolt (Straight Bolts) 11165 81130 81131
350 Journal, No Register 7.245 Wide (Angled Bolts)2 11190 81128 81129
400 Journal, 2 or 4 Bolt Blocks (Angled Bolts) 11180 81128 81129
400 Journal, Front Cap, 2 Bolt 11183        
400 Journal (Straight Bolts) 11185 81130 81131
             
BIG BLOCK CHEVY MAIN CAP # STUD KIT #
w/o windage tray
STUD KIT #
with windage tray
             
396-454, 2 or 4 Bolt Blocks (Angled Bolts) 11200 81133 81134
396-454 (Straight Bolts) 11205 81140 81141
396-454, 4 Bolt Front Cap (Angled Bolts)3 11210 (Note 6) (Note 6)
396-454, 4 Bolt Front Cap (Straight Bolts) 11211 (Note 6) (Note 6)
         
FORD MAIN CAP # STUD KIT #
w/o windage tray
STUD KIT #
with windage tray
             
302 - 2 Bolt Caps (Straight Bolts) 11400 81155 81156
351W (Angled Bolts)4 11420 81175 81164
351C (Angled Bolts) 11440 81169 81170
351C, Front Cap (Angled Bolt) 11445 (Note 6) (Note 6)
429/460 (Angled Side Bolts) 11450 81188 81189
             
CHRYSLER MAIN CAP # STUD KIT #
w/o windage tray
STUD KIT #
with windage tray
             
318-340 (Angled Bolts) 11300 81183 81184
360 (Angled Bolts) 11310 81183 81184
354 (Angled Bolts) 11320 81183
392 (Angled Bolts) 11350 81183
426-440 RB Wedge, 2 Bolt (Straight Bolts) 11360 81183
383-400 Low Block Wedge, 2 Bolt (Straight Bolts) 11361 81183
383-400 Low Block Wedge, 2 Bolt ( Straight Bolts) 5 Cap Set 11362 81183
426-440 RB Wedge, 2 Bolt (Straight Bolts) 5 Cap Set 5 11365 81188
         
PONTIAC and OLDS MAIN CAP # STUD KIT #
w/o windage tray
STUD KIT #
with windage tray
             
Pontiac 421, 428, 455 (Angle Bolts) 11520 81222 81224
Pontiac 421, 428, 455 (Straight Bolts) 11500 81222 81224
Pontiac 421, 428, 455 (Front Cap Only) 11501        

Pontiac 350, 389, 400 (Angle Bolts) 11525 81222 81224
Pontiac 350, 389, 400 (Straight Bolts) 11505 81222 81224
Pontiac 350, 389, 400 (Front Cap Only) 11506        

Olds 400, 425, 455 2 Bolt Caps (Straight Bolts) 11550 81175
         
AUSTRALIAN HOLDEN MAIN CAP # STUD KIT #
w/o windage tray
STUD KIT #
with windage tray
             
253-308 (Angled Side Bolts) 11570 81145 81146

NOTE: 1 - Narrow register 4.490" wide.
2 - Wide register 6.200" wide.
3 - Requires slight pan clearancing in some areas.
4 - Requires SVO block pan notch or clearencing #4 main web area of pan.
5 - Bolts must be used on #5 rear main due to space limitation of rear seal.
6 -Studs for front caps are included in the 4 bolt kits.

For maximum strength, the installation of Milodon main studs are highly recommended.