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440 main bearing size

440brian

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I'm trying to put my 440 back together, I think it's about a 76 block. The new main bearings are not even close. They are a sealed power 4094 m 20. Jegs web site said b/rb mains. Is the 383 400 mains not the same as a 440, or something?
 
I'm trying to put my 440 back together, I think it's about a 76 block. The new main bearings are not even close. They are a sealed power 4094 m 20. Jegs web site said b/rb mains. Is the 383 400 mains not the same as a 440, or something?
440 has larger mains than the 383 and 400
 
You have 383/400 mains. 440 journals as you have seen are much larger. If you have a 74 or newer block this is yoour part number in Sealed power.
Sealed Power MA Series Main Bearings 5025MA
Doug
Clevite 77 Main Bearing Info.​

Because "B" (361/383/400) and "RB" (413/426/440) engines use different size main journals, each will have a different size main bearing. The "RB" uses a 2.750" main journal diameter, while the "B" uses a 2.625" so the two sizes are specific to each engine, however there is one additional difference...

From the beginning of production (when these engines were designed) in 1958 up until the 1973 model year the diameter of the thrust surface's outer edge (on the #3 bearing) will be approximately 3.470" for the "B" engine and 3.600" for the "RB" engine. Starting in the 1974 model year, this diameter was increased approximately .280 thousandths to 3.750" for the "B" engine and 3.880" for the "RB" in order the give the thrust surface more surface area. To allow the new larger bearings to fit, the machined recess area in the block webbing and the main cap in which the thrust bearing shells fit was increased an equal amount.

In the picture below, we have put two #3 thrust bearing main caps together. The one on the bottom is from an early block, and the one on top is from a late block. You can see the difference in the size of the machined recess area.
 
As stated above, 4094M is for low blocks, 4095M is for RB's. Since your block is a 1976 you can get large thrust mains bearings if you want to (not necessary) but those are different numbers.
 
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