Correct Flex Hone Tool? Grit/Size

Posted by 90turbotsi, Dec 13, 2005

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  1. 90turbotsi

    90turbotsi Proven Member

    Joined Sep 15, 2002
    Owings Mills, Maryland
    I have read through past threads but not gotten too much help from it thus far. I am looking to purchase an flex (ball) hone tool for 4G63 blocks. Up until now all of the motor rebuilds I have had to do I was able to borrow a flex hone tool from friends from his shop. However he has since moved and thats not longer an option. I have talked to a few local places but none have what im looking for or read I needed.
    From my readings I see best results with 240-320 grit, is this correct? My local place only has 120 grit but I can order online a 240, no place thus far has anthing higher in the right size. Also I can not find metric... ive located a few 3.5inch units which are "good for" 75-90mm bores (obviously our 85mm will fit in there fine) Im willing to just order one online but wanted to ask here before I do. Thanks

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  2. SlowSpyder

    SlowSpyder Proven Member

    Joined Oct 27, 2002
    Los Angeles, California
    just out of curiousity, do you measure the cylinder bore after going at it with a flex hone??
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  3. project_tsi

    project_tsi DSM Wiseman

    Joined Sep 4, 2004
    Eau Claire, Michigan
    We picked up this clyinder hone from Sears found here
    It seemed to work fine for us. The correct way to use a hone device is to keep the hone as vertical as posible while making 3-5 quick passes through the cylinder walls. DO NOT do it more then that or go slow while honing, b/c a good hone CAN actually bore out a cylinder very slightly, and you do not want that. The function of a hone is to basically "scuff" up the cylinder walls to provide a new surface for the new rings to seat in. Its not meant to remove any material.

    OK, for some reason the link will not work if I paste it in here but it was a hone from Sears and cost approx $21.
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  4. 99gst_racer

    99gst_racer Moderator

    Joined Apr 5, 2003
    Coloma, Michigan
    I had a hell of a time locating a bead style hone for my block. Most local engine builders in my area prefer the bead style (ceramic balls). I called around and there were none of that size (85mm) to be found. The average price I got on a 4" was roughly $65 and I didn't really want to spend that much either.

    As Dan stated above, I found mine at sears. It's the stone type and it's adjustable per diameter. I paid a little more than $20 for it and while I was there, I also notice they sell replacement stones for $5 for a 3 pack. Not too shabby.

    The stone type worked very well for me. Like Dan said, only make about 3 quick passes through the cylinders. Be careful you don't go too low and hit one of the squiters.
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  5. Injected

    Injected Proven Member

    Joined Apr 29, 2004
    Houston, Texas
    How well do these work in comparison to having a machine shop use an industrial grade honing device? I know some one will say, "It all depends on the person who is doing the honing." I'm having the main caps on my G4CS align honed for straightness and roundness (I wouldn't trust myself to do this operation myself, and besides I don't have a large enough lathe to). Have any of you guys gotten into this? I was going to have them go ahead and align hone the cylinders to reach the final bore width, but getting my own and using a large drill press/boring maching sounds like something I would like to get into.
  6. 90turbotsi

    90turbotsi Proven Member

    Joined Sep 15, 2002
    Owings Mills, Maryland
    Actually spoke with a friend/engine builder... he recommended a place to order it. Its called McMaster Carr I believe ( I need to find my invoice ). I ordered it and got it the next day :thumb: and only cost me $35. The 3.5 inch unit is for our size bores, stock or overbored. I ordered a slightly higher grit of 240 so it would make the proper crosshatch and eat less material away(comes in 120 180 240 320 grit). Also made this decision after reading a few older posts on how to hone.

    The flex hone is very easy to use... and I like it far more then the other ones with the 3 stones. Plus I used one of these at the shop I previously worked at so I know how its done. NO I did not hone the hell out of it and all like im sure could be done, just enough to ensure a good crosshatched pattern and I made sure the tool was well oiled so it did not damage anything. Its user friendly as long as you dont hone the hell out of the block or go too fast, plus no need to adjust things with it. And in response to someones question most machine shops use these, mine had only this type but in a lesser grit.
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    Twizted99GSX and Injected like this.
  7. 90turbotsi

    90turbotsi Proven Member

    Joined Sep 15, 2002
    Owings Mills, Maryland
    Here, now that I have my invoice it may help out others in the future:


    Look it up under the flex cylinder hone. Or my part number was 4424A232 (on their site) its a 3.5 inch with 240 grit, but again they have multiple other grits and sizes available but this size is correct for a 4G63 bore. Came to $35.72 which was CHEAP as I looked them up and thought I was going to have to pay $75+ for one.

    Oh and I removed my oil squirters when I did this, no reason to leave them in and hav to be super careful not to hit them... remove them and clean them all out at the same time, then replace the crush washers and reinstall :)
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  8. bullettdsm

    bullettdsm N/T DSM Wiseman

    Joined Dec 17, 2004
    East Hampton, Connecticut
    NICE :thumb: ! I also wanted the ball type (better crosshatch and easier). Had a helluva time finding one and ended up getting the 3 stoner. Not that it mattered on the block that I was doing. I ended up finding a crack while I did a clean up hone. :rolleyes:
  9. Big Woo

    Big Woo DSM Wiseman

    Joined Sep 9, 2002
    Grand Rapids, Michigan
    Since this thread concerns a subject I know a little something about, I thought I would share some additional information.

    Honing is a machining process therefore it removes metal. DO NOT trick yourself into thinking that just because you only perform several quick skirmishes up and down the bore that nothing is being removed. If nothing was removed then the cylinder would look and feel the same after you are done.

    A more accurate description of the honing process would be.
    The honing stones have a relatively large area of abrasive in contact with the work at relatively low speeds and low pressure. Surface temperature is low and there is no surface damage. Honing produces great accuracy and very fine surface finishes. Honing also provides a stress free base metal surface in the bore. The honing operation produces geometrically perfect bores with a crosshatched base metal finish having thousands of microscopic pockets that are ideal for supporting a uniform lubrication film.

    Remember that used cylinder bores are not straight, round or anywhere near perfect. They are typically barrel shaped and tapered, but can also be bell mouthed, be out of round and have a wave to them. A ball type hone, or a flexi-flyer (spring loaded 3 or 4 stone hone) WILL NOT improve or remove any of these conditions within a given cylinder. They will simply just remove a small amount of material, and leave the cylinder in the same shape.

    The only way to straighten a used cylinder is use a rigid style hone, or if the cylinder to too damaged, increase it to the next available oversize. A rigid hone is just what it sounds like; it does not conform to the shape of the cylinder and simply re-finish it. It instead supports the stones and scrapers firmly and hones the cylinders back into shape.

    I am not saying that someone cannot use a ball hone to de-glaze their cylinders, re-ring the motor and have good results. Results depend greatly on a myriad of other factors. However there has been numerous threads started, with a title something to the effect of “Just rebuilt motor low compression numbers HELP” Many people attribute this to poor engine break in procedures, and I know of many ways to break in an engine, and I have my own favorites, but I will offer this one truth. If you have a machining/honing problem with the cylinders of any motor, no break in procedure will save it.

    To the question above regarding align-honing.
    Align-honing the main bearing housing diameters is done on a specialized machine, with a honing mandrel long enough to hone all of the main bearings simultaneously. This will maintain the geometric placement of the main bearing housings on all three axis’s X, Y, &Z.
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