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Author Topic:   Engine Block Core Shift
posted June 09, 2004 10:21 AM
If you look at the front of an engine, usually, you can see this in the location of the cam hole....if the cam location was drilled to one side or the other, then you have a block that may have cylinder walls that are thinner on one side or the other....they drill these blocks from centerline on the cam hole which will tell you somewhat how thick the cylinder walls are from one side to the other....better blocks will have the cam hole drilled right in the center of the casting of the location...look at it, you will understand from there...hope this helps.


posted June 09, 2004 12:17 PM
It also could be that just 1 or 2 cylinders moved. When the blocks are cast, the molds can easily shift as the iron is poured. There's small wires that hold the 'pieces' in place (ever see the little rods in the coolant passages on some Ford blocks?) It's not uncommon for these to move and the walls of the block to not be in the exact right place. That's practically impossible to see unless the block is sonic checked.

Don't feel like making a nice drawing, but picture this.

Perfect block = | bore |

Core shift = / bore /

So, on the shifted block, the cylinder walls will be thicker on one end and thinner on the other. That's why some blocks will take .060" and others will crack.

Hope that makes some sense.

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