I'm wondering if they don't want the cylinders honed because of possible lack of proper cleaning after. I am assuming this piston replacement was done with the block still in the car. Usually after honing the block would be put in the cleaner before assembly. But an in car hone with a dingleberry hone usually just gets some garden hose water and some sprays of WD40, at least for any of the LS based engines my friends and I have built.
I don't think so, look at it this way if the original hone marks are still in the complete bore and no ridge then the bore is going to be okay.
If it was out of round or tapered the crosshatch would be worn in places, that alone would tell me anyway there is something no kosher with this cylinder and probably needs either a re-bore or a hone or both.
The problem I am seeing in this thread is the lack of differentiating between a hone and a glaze busting. Honing a cylinder is a very precise process using specialized machinery that has specific pressures on the tooling and a feed rate that provides the correct finish, this cannot be done with some cheap tooling and an electric drill.
Using a ball hone for glaze busting was at one time very common but it can make a bugger out of an otherwise nice bore. Cylinder glazing is rare today. This is a real honing machine with tooling. At most if all the crosshatch is there clean it with WD40 and lightly with 00 steel wool.
The best example of this are the Subaru engines, they have a piston to bore clearance of only...
Corresponding Grade A and B pistons will have a piston to wall clearance range of . 0023”- . 0031”. The piston to wall clearance gauge point for all Subaru graded pistons is 0.850” from the bottom of the oil ring.
The A and B pistons are very slightly different size so its not hard to imagine the damage a improperly used hone can do.
If the cylinder bores are not pristine on any engine then a machine shop should be consulted and let the folks with the right tooling and experience do it.
As far as the original finish varying all over the place, it is not, the hatch is either there on the whole bore or it isn't, period, if it isnt machine shop time unless you have one of these and know how to use it (I don't own one but I do know how to use it).
Edit: This is what Sunnen has to say about ring break in. Another myth seemingly busted (as far as most new engines are concerned anyway.
If desired, a second honing operation using specialized tools can follow initial honing to create a plateau finish in which the peaks are uniformly clipped at a consistent level while leaving the valleys untouched. Most engine cylinders today are honed with this plateau surface finish, which increases the bearing area of the bore surface. This means conventional piston ring “break-in” processes are not required and the microscopic peaks that are honed off before the engine is assembled do not end up in the engine oil upon startup.
