I'm an experienced machinist but not so much with automotive machine work. I bored my 270 block for .020 over pistons and left .005 for honing. In hindsight I probably should have bored within .002 or .003.
I'm hand honing with a Goodson hone (clone of a Sunnen An-112)

My problem is I'm getting some taper with the bottom of the cylinder being .0005-.001 smaller than the top. I'm extending about an inch out the bottom of the bore, which is as far as I can go without hitting the main bearing webs. I've tried dwelling at the bottom but it seems by doing that the center of the bore starts to get larger.

The cylinder gets warm during honing so I have to wait for it to cool to get a good measurement. It does seem to measure a little straighter cold than warm.

I have considered setting the boring bar back up and sneaking a little more out of the bores.

Any advice on technique?

BTW: I did discover that it's possible to flip the stones end-for-end and run the hone in reverse. When using a honing machine it's good practice to flip the part regularly to keep the hole straight and stone wearing evenly, but I'm not sure if it's helpful on an engine cylinder or not.

Last edited by G508; 03/13/2026 10:14 PM.