2020 Product Showcase: Big-Block Mopar B/RB Main Caps From Milodon

When it comes to big-power big-blocks, if you aren’t using an aftermarket block, you will need to at least upgrade the main caps. This has been something that Milodon has known and addressed for a number of decades. But, just because they’ve done it for decades, doesn’t mean they aren’t constantly reevaluating their designs.

Case in point, Milodon’s newly redesigned big-block Mopar B/RB main caps. These caps are available for both the 383/400 B blocks and the 440 RB blocks, and not only incorporate improved steel alloy for additional strength, but also “Hemi style” cross bolts. “With these new caps, no register machining is necessary, and the cross-bolts don’t interfere with the oil pan bolt holes like other designs,” says Steve Morrison, President of Milodon.

In fact, the machining required for these is pretty minimal considering the payoff of the upgrade. “All you need to do is machine the inside of the block out to four inches either side of the crank centerline, an inch-and-a-half deep, and the cap is ready to drop in,” Morrison explains. “Then you drill the cross-bolt holes in the original Hemi location (.875-inch down) and tap the cap thread.”

From there, a quick align bore, and your big-block Mopar now has the strength of Hemi-style main caps, for a minimal investment. The caps are available in both three-cap and five-cap sets, the former just replacing the three center main caps, and the latter replacing all five main caps on the engine. Plus, as a point of pride for the whole Milodon team, the caps are made entirely in America.

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About the author

Greg Acosta

Greg has spent seventeen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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