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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Exchange/Return Notes
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  • Final sale items are not eligible for returns or exchanges.
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SKU: 49070601880

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jelly
Port Orchard, US
★★★★★ 3
Too firm throughout, but no support
Size: 57 Inch, Color: Light Yellow
I like the feel of the fabric but it's honestly not comfortable for me. The stuffing makes the pillow way too firm and I wake up with sore neck muscles. I do appreciate the body length, (I am 5'3) and it's comfortable for a little while, but not for the whole night. Especially because I have to get up multiple times to use the bathroom, and this pillow just gets in the way. I decided to just use three different pillows for my head, my legs and my arms/back at all different firmness so I get the support I need. If you are able to deal with the firmness of the pillow throughout, this might be a good option for you. I also ordered the cooling option and this does not help keep me cool at night. Even with the AC on and the fan running. It sleeps hot. I ended up storing it back in its vacuumed sealed bag and put it away.
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Reviewed in the United States on August 19, 2025
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Kimberly Suarez
Bozeman, US
★★★★★ 5
Who Says Pregnancy Pillows Are Just for Pregnancy?
Size: 57 Inch, Color: Light Grey, Size: 57 Inch, Color: Light Grey
I bought this pregnancy pillow even though I’m not pregnant, and I have zero regrets! This thing is incredibly comfortable and provides support in all the right places. Whether I’m sleeping, reading, listening to an audiobook, or just relaxing in bed, it helps me get comfortable and stay comfortable. I love being able to hug one side while supporting my back with the other. It feels like being surrounded by pillows without having to constantly rearrange them throughout the night. The only downside is that it takes up a decent amount of bed space, but honestly, that’s a sacrifice I’m willing to make. My family may disagree. 😆 If you’re considering this pillow but aren’t pregnant, don’t let the name stop you. Comfort is for everyone!
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Reviewed in the United States on June 5, 2026
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W.
Port Orchard, US
★★★★★ 5
Comfortable, firm, great for positional sleep therapy
Color: Cool Grey, Size: 24x24x12 inch
This is just what I needed to breathe better in my sleep, my doctor recommended a pillow like this for sleep apnea symptoms. I have an upcoming surgery too, so i'm glad I was able to test it out a week prior and see how it can help me prop up in bed. Feeling better about my upcoming recovery knowing i'll have this great pillow to support me!
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Reviewed in the United States on April 4, 2026
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Kristin
New York, US
★★★★★ 5
Literally perfect and exactly what I needed!
Color: Cool Grey, Size: 24x24x12 inch
I can't recommend this enough! It was exactly what i was looking for! I have an annoying habit of researching everything for months before I purchase something that will get used this often. I finally decided on this one and I was very pleasantly surprised. I needed a wedge pillow to put at my back while sitting in bed. Mostly for when I'm working on my laptop. This one was the perfect height and perfect fit for me.I'm a female that is 5'4 and weigh about 117pds. I wanted something firm enough to support my back, and this most certainly does! It had a very pleasant appearance with the light gray sides. It has a removable cover I can take off and wash when needed. It's portable enough to move from room to room, also works great on my couch and it has amazing versatility. It can also be used as a pillow for someone that might need to sleep at a slight incline. It also works if you need to prop your legs up. It came vacuum packed. Once opened It said to let is sit for at least 24-48 hrs to give it time to properly inflate. For me, It plumped right up immediately! Again, from someone that does her research, if your looking for something like this at a reasonable price, this is it!
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Reviewed in the United States on May 10, 2026
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Becca
Battle Creek, US
★★★★★ 5
It was worth every cent
Color: Cool Grey, Size: 24x24x12 inch
I have BPPV. It's a condition where tiny ear crystals come out of place and move within your ear canals - this fools your brain into thinking you're in motion, causing severe dizziness. The most common treatment is the Epley Maneuver, and that actually helps a lot. However, I was going through a period where every single day I'd wake up with severe dizziness. Even if I managed to do the Epley Maneuver and it worked, the entire rest of the day would be ruined because I'd still feel generally unwell and nauseous. I ended up getting a book about BPPV and the author strongly recommended sleeping at at least a 30 degree angle. So, that's why I ended up buying this wedge pillow... I started using it April 26 and today is May 17. Since I began using it as a pillow, I have not woke up dizzy again. That is so huge! It may be that sleeping at a 30 degree angle deserves 5 Stars but thought I'd give this pillow 5 Stars too, as it's been a great experience. If you suffer from this, here's how the angle should be...If you lay your head on a pillow and open your eyes, you should not be looking at the ceiling. With the right angle, you should be looking at where the wall meets the ceiling. If so, you know you're at the right angle. As far as pillow itself, I'd say the pillow case fabric is of average quality. Not really remarkable in any way. It seems decent. Good value for the price. The inside is firm (which is just what I needed) but comfortable, and I tend to not move around much the entire night. I like this very much and if it does start wearing out, I'll definitely come back here and buy another. Would recommend.
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Reviewed in the United States on May 17, 2023

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