Does Line Honing change the crankshaft's centerline?

famous bob said

Exactly -YES . Depends on how much the machinist takes off the main cap mating surface.
I have always used a .005 under chain on blocks I had bored or honed , including 2 hemi`s , a couple of sbc`s , and the is one/ The 440 block I have now , the .005 under chain was so tite I had trouble getting it on/together . Its hanging in there just great .

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Exactly. It’s going to depend on how far off the mainline is to start with. And if some joker got in there first and did some voodoo magic **** to the mains.

If you have to cut the caps more than .002ish it’s probably going to move the centerline. If you have to take more than about .004 off the caps you should really use the line bore first. Much quicker and easier to keep everything where it needs to be. The more heat you generate the more time it takes to do it right.

I suspect it won’t be long before a CNC line hone is made commercially available. It will have Diamond stones rather than vitrified abrasives and use water based coolant, just like a cylinder hone.

I could be wrong about that, but I do know many shops are now using a profilometer to measure the surface of the main bores. That usually means the OEM’s are going that way and te rest will follow.