The grit depends on what type of rings are going to be installed:
OEM Iron rings: 180 or 240 grit
Chrome rings: 240 or 320 grit
Moly Rings: 320 or 400 grit
Plasma Rings: 320 or 400 grit
I found this very useful when I honed my first block:
How do I refinish my bore
There are several steps in refinishing your cylinders in preparation for new rings. The first of course is to remove all bearings leaving a bare block. The metal from the honing or deglazing process with go everywhere. Note that the worst thing about honing is the block cleanup. You can never spend too much time cleaning your block. With the engine bare and cylinder ridged reamed (if necessary) place the hone in a hand drill or drill press. Lubricate the cylinder with 10-30wt oil or honing oil (recommended). Spread the lubricant in the bore with a brush or your fingers. Make sure the cylinder is completely covered. For the first use of a new hone lubricate the bore several times as the hone itself will absorb some of the oil. Future cylinder honing will not require as much oil as the first was with a dry hone. Insert the hone with the drill rotating slowly while inserting in to the bore. With the hone in the lubricated bore, run the drill at 600-800 rpms with a vigorous motion up and down in the bore for 60-80 strokes. How vigorous a motion? basically as fast as you can move your arms. You are seeking a 45 degree crosshatch in the bore. If you are not achieving a good crosshatch, you will need to slow the drill speed down to achieve the MUST HAVE 45 degree crosshatch. Run the drill for 60-80 rotations and wipe the bore with a clean cloth. Inspect the bore. If any dull grey areas are visible (they will stand out from the freshly honed surface) continue until the bore is completely resurfaced. While honing, continue to squirt oil into the bore as a medium to flush away the cylinder material. Once the bore dull grey color is not visible STOP honing. The most important step is the cylinder wall cleanup. Use a nylon cylinder wash brush or a clean cloth soaked in warm soapy water and run up and down the bore. Continue this process while flushing the bore with warm soapy water. The goal is to remove every microscopic particle that is embedded in the cylinder wall grooves. After extensive scrubbing take a clean white lint free cloth with warm water and wipe up and down the cylinder bore with force. Inspect the cloth, if you see grey on the cloth, and most likely you will, you need to go back and clean the bore again. Repeat until you see no grey on the white cloth. Once each and every bore is perfectly clean then coat each cylinder with oil to preserve until piston placement. Once again the bores must be clean or you just left lapping compound in your high dollar engine.
Achieving A Cylinder Crosshatch Pattern
Another misunderstood and highly discussed topic is the subject of cross hatch angle. The resulting cross hatch angle produced by a three spring hone (or a rigid hone for that matter) is strictly a function of stroke rate versus RPM. Most OEMs and ring manufacturers state the angle of the scratches in the crosshatch pattern should be about 27 - 45 degrees with 45 degrees the optimum. This angle is referenced from the top of the deck. The crosshatch angle should be consistent throughout the cylinder walls. If the crosshatch angle is too steep the cylinder walls will not retain sufficient oil to aid in the rings seating process. The problem is that the rings will pump oil and rings will rotate too quickly leading to accelerated ring and ring groove wear. To shallow of a angle can cause a chattering affect as the ring passes over the valley preventing the ring from receiving proper lubrication again leading to excessive ring wear, excessive ring break in time and the possibility of engine smoking with no ring seating. To achieve the desired 45 degree crosshatch run the drill at 600-800 rpm and vigorously run the drill up and down in the bore. This vigorous movement of your arm is exhausting but you only need to run the tool in the bore for 10-15 seconds. Then inspect the cylinder surface. If you see a dull grey surface that indicates the hone was ineffective in that area thus continue to run the hone until the complete bore looks exhibits a fresh cut with a cross hatch pattern.
