Originally Posted by Diesel911

If you live close to San Diago CA there used to be a place there that machined and rebuilt high end european Cars.

The typical Boring Bar machine that you see here in the US mounts on top of the Block and the part that clamps it goes down through the adjacent cylinder or the machine is held on magnetically. The problem with them is that you have to shift the boring bar around by hand to center it (centered with a dial indicator I assume on the unworn part af the cylinder at the bottom).

If the to surface of the block is not level the new cut is going to be at a slight angle.

I went to that shop to by Parts from but also took my Volvo Diesel Cylinder Block to be rebored to fit new oversized pistons.

They had the equipment that you likely need. It was like a huge milling machine. The Block is swung into the machine lowered onto a rod that is the size of the main bearing Bores and the Bearing Caps are out on fromt there. Bore alinment has nothing to do with the top surface of the block.

I did not get to watch them do the centering in the bore but the Block sitting on that Rod but all of the adusments on the Machine were similar to a milling machine. Meaning they had accurate adjusments.

Once a cylindeer was cut all they had to do was change the head on the Machine and they could hone the cylinder to a more precise side as well as doing the cross hatch pattern.

The Machine looked big enough to do a Cummins Big Rig Truck Engine.

That was back in 1992 and I don't remember the name of the place nor know if it is still in business.

Originally Posted by t walgamuth

This is all necessary because the block (at least on an inline engine) twists with use. To do the job correctly the top of the block therefore needs to be decked so that the deck is parallel to the crank as it was from the factory. Once it is parallel again it can be bored and the bores will be perpendicular to the crank. I suppose if you don't do all this all your bearings will not be even in their clearance across the face so it will be like an engine with high mileage even though all the wearing parts are new.