King Engine Bearings Main Bearing Set for 1969-1971 Mercury Cyclone (MB5504SI)
SKU: 49070601880

King Engine Bearings Main Bearing Set for 1969-1971 Mercury Cyclone (MB5504SI)

Sale price$25.11 Regular price$27.90
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Description

King Engine Bearings Main Bearing Set for 1969-1971 Mercury Cyclone (MB5504SI)Carrying on a tradition of durability and dependability, KING Bi Metal (aluminum) engine bearings feature 100% lead free aluminum silicon. King has 4 different variations of their aluminum based bearings: (AM Series) K 783 Standard aluminum based material, equivalent to SAE 783, used for low and medium load engines. King AM Series main and rod bearings are recommended for street or marine applications. They have superior embeddability, which provides

Carrying on a tradition of durability and dependability, KING Bi-Metal (aluminum) engine bearings feature 100% lead-free aluminum silicon.

King has 4 different variations of their aluminum based bearings:

(AM-Series) K-783 -Standard aluminum based material, equivalent to SAE-783, used for low and medium load engines.

King AM-Series main and rod bearings are recommended for street or marine applications. They have superior embeddability, which provides greater macro-particle and reduces scratching of the crank journals and tearing or weakening of the Babbitt overlays. The direct replacements feature tolerance control up to +/- .0001—and they're lead-free, making them environmentally friendly and user-safe. Order the King AM-Series rod bearings in the application designed for proper fitment with your vehicle.

(SI-Series) K-788 -Aluminum based material, strengthen by 2.5-3% silicon, for medium load engines or nodular cast iron crankshafts.

King SI-Series main and rod bearings are recommended for OE applications. These replacement bearings are designed for aftermarket gasoline or diesel engine rebuilding—and performance engines with factory crankshafts. The bearings have an improved crankshaft finish for reducing microscopic ferrite peaks on improperly ground or polished nodular cast iron crankshafts. King SI-Series main and rod bearings feature improved oil clearance to reduce wear and increase engine life, which in turn reduces operating noise, vibration, and excess oil flow. Order the bearing set designed for fitment on your make and model.

(SM-Series) K-789 -Aluminum alloy bonding layer. The strongest aluminum based material. The alloy is strengthened by addition of Manganese and Chromium (Mn, Cr), Used for high load applications.

For high load and performance applications, King SM-Series main and rod bearings are the strongest aluminum-based material offered by King. The alloy is strengthened by the addition of manganese and chromium. SM-Series crankshaft main bearings feature a traditional steel-backing, aluminum bonding layer, and the aluminum bearing alloy. They are available for a wide variety of vehicle and engine applications.

(HP-Series) K-787 - King HP-Series rod bearings were developed mainly for drag race applications needing a material harder than the Babbitt top layer. These applications demanded a structure that could withstand high loads for short durations and still offer higher embeddability and compatibility. In response, King developed the HP-Series featuring the Alecular metal structure.

The HP-Series is also suited for many performance applications with nodular cast iron crankshafts, such as street, strip, and some levels of Circle Track racing.

HP-Series bearings are particularly suitable for the following cases:

  • When a tri-metal bearing's Babbitt overlay extrudes over the sides, migrates to one end, or is physically removed by the crankshaft
  • When the intermediate layer of a tri-metal bearing is exposed, damaging the crank journal and requiring expensive grinding or replacement
  • When contaminants enter the oil stream, scratching and damaging the crankshaft journals


Check your bearing size using our fitment calculator here
Shipping Notes
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  • Except Preorder products are shipped in 48 hours.
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Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
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SKU: 49070601880

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Paige
Battle Creek, US
★★★★★ 5
Definitely worth the price
Size: 6.5, Color: Black/Black
Absolutely love these boots! I originally bought them to wear in NYC in December & they did not disappoint. They were comfortable, cute, durable and worked well in the slush/snow. The traction on the bottom is also nice! They kept me warm with wool socks. I wear them almost daily now. Perfect for everyday. easy to wear with variety of outfits. Good every day shoe.
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Reviewed in the United States on January 3, 2026
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Kimberly
Lexington, US
★★★★★ 5
Snagged a deal
Size: 7, Color: Redwood/Gum 10
I waited and waited to get these boots! I knew I was chancing it, but they went on sale, and I snagged them! I am a size 7, and they fit nicely with socks. a little loose, barefooted, but what psycho wears boots without socks? They are comfortable and really well-made.
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Reviewed in the United States on April 8, 2026
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ashlynnk
Phoenix, US
★★★★★ 4
Cute, comfortable waterproof boots (a little snug to put on)
Size: 7, Color: Velvet Tan/Gum 2
These are really cute Chelsea-style boots and feel very comfortable once they’re on. The waterproof material is great for wet weather and the sole feels sturdy with good traction. They look stylish enough to wear casually but still feel practical for rainy days. The only downside is they can be a little difficult to put on at first because the opening is somewhat snug, but once they’re on they fit well and feel supportive. Overall they’re a great waterproof boot and I’ve enjoyed wearing them.
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Reviewed in the United States on March 17, 2026
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Abby B
Lowell, US
★★★★★ 5
Surprisingly great for my wide feet and high instep!
Size: 10.5, Color: Velvet Tan/Gum 2
So thrilled I took a chance on these. Finding boots is impossible for me. I have wide feet, a super high instep, a bunion on one foot, and I wear a hard to find size (10.5). I ordered the 10.5 and 11 in these expecting I might need to size up for width (if I could even get them on). It was a struggle getting the 10.5s on the first time, and once I did they were somewhat uncomfortable on the top of my left foot. But I read that they would relax so decided to give it a go because I need waterproof boots for an upcoming trip and the 11s felt too long. After two days of light wear, they are already breaking in and I have no more discomfort. Getting them on is already easier and they are plenty wide enough and very comfortable to walk in. These are true to size. Super happy and worth a day of mild discomfort to break them in!
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Reviewed in the United States on March 7, 2026
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EE
Whiting, US
★★★★★ 5
Comfortable, sturdy, waterproof
Size: 9.5, Color: Black/Black
Loce, love, love these boots. Have walked ten miles with no foot pain around NYC. They go with everything and and are so comfortable. As they are waterproof/resistant, they get a little warm in high temps, but perfect three-season boots.
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Reviewed in the United States on May 17, 2026

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