Flex Hone grit size

KdancyKdancy Posts: 2,471Senior Contributor
edited January 2 in HUDSON
I am cleaning up and installing new bearings and rings in a 232.
Which grit size should I need for the bore glaze? Seems that 240 or 320 would be the grit needed ?
Grit        Color
20           Brown
40           Purple
60           Gray
80           Orange
120         Silver (no color)
180         Red
240         Navy Blue
320         White
400         Yellow
600         Pink
800         Light Blue


  • KdancyKdancy Posts: 2,471Senior Contributor
    Ok, just found this info---

    traditional honing procedures require no finishing step. Typically most ring manufacturers recommend using #220 grit silicon carbide honing stones if the engine will be assembled with plain cast iron or chrome rings, #280 grit stones for moly-faced rings, and #320 to #400 grit stones for moly rings if the engine is being built for racing or performance. Even so, the cylinders can still be plateaued to some extent by finishing them with some type of flexible brush.
    One of the advantages of using a flexible brush in a drill is that you can run the drill backwards. Honing stones usually run clockwise so if you brush in the opposite direction (counterclockwise) it will do a nice job of deburring the surface. No more than 15 strokes should be necessary to produce a high quality finish.

    If bores are honed with #325 to #400 diamond stones, the finish will typically be in the 22 to 24 Ra range – which is too rough. That’s why the bores need to be finished with a brush or finer grit stones. Doing so will usually bring the finish down to the desired range of 20 or less.

     At a microscopic level, the profile of a freshly honed cylinder wall reveals many little peaks and valleys. The valleys are cut out of the metal by the abrasives during the honing process, and the peaks represent the highest point on the surface that will make contact with the rings. Large, sharp peaks won’t last long once the engine is started because the tops of the peaks will be gradually sheared off by the rings as the rings break in. As the tallest peaks are knocked off, the mountains become flattened creating a “plateau” effect. This increases the bearing area for the rings and makes it easier for the rings to glide over the surface on a film of oil that is retained in the valleys.

    According to one piston ring manufacturer, once the rings have seated, wear virtually ceases because the rings are now supported by that thin oil film and no longer make physical contact with the cylinder wall.

     A plateaued bore surface will stabilize after about two hours of running. In other words, the rings will seat very quickly and experience almost no further wear. A more conventional surface finish, by comparison, may take anywhere from three to 12 hours to seat in depending on the grade of stones used. A bore finish honed with #280 grit stones will seat faster than one finished with #220 stones.

  • Uncle JoshUncle Josh Posts: 2,658Senior Contributor
    I wouldn't use chrome rings in a Hudson with the chrome/alloy block.  Also as the rings get old, they're subject to 'hydrogen embrittlement'.  I took a 52 308 apart and 5 of the top (chrome) rings were broken, one in 3 pieces.  She's running good now and in Gottengen Germany.
  • GeoffGeoff Posts: 3,920Senior Contributor
    Both the Hornet and Jet for '53-'54 used Chrome rings, yet the 262 and 232 used iron.   Strange!  Did they alter the  block composition?
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