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Brettw

Bore gauge

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Brettw
Looking at a dial bore gauge tool. However, is this the proper tool for measuring the bore of a cylinder? If not, do those in the know have suggestions? Thanks

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BLT
First of all, how bad does the bore look? If you can see hone marks all around , I use a new compression ring and see what the end gap reading is and if it is well under the max allowed, I clean up the bore with a large hone to knock off the glaze and install a new set of rings, reface and lap in the valves and away you go. On standard bore engines I also have had good luck with chrome ring sets. The Briggs manual says no honing is required on a clean bore. I have a Briggs IC 12HP engine on a Broadmoor going into it 14th year after being re-rung with chrome. Oil consumption has been zilch since day one.

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wilm169
Look at this one; http://cgi.ebay.com/2-to-6-DIAL-BORE-GAUGE-TOOL-caliper-mic-micrometer_W0QQitemZ360240917986QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item53e0082de2

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Brettw
Thanks to both of you for your help so far. Bob, the cylinder and the rest of the engine are in great shape, but it needs a piston and ring set.
quote:
I use a new compression ring and see what the end gap reading is
I would do the same, use a feeler gauge to check end gap and see where I end up. Problem is, I need to measure first to determine if I need to order a .10 oversized kit or not. This is a K321 which I believe is a 3.50 bore. When one individual measured it, he seemed to believe it was well within these tolerances. However, I do not want to order a kit and have it be to small. I'd rather measure myself, and then have the tool for life. Levi: That's one I am looking at. My question is, is it the best tool for what I am trying to measure. I am not very experienced at measuring inside cylinder bores.

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stevenj
The dial bore gage reads deviation from a set diameter. You need to set the dial to zero at a specific dimension and then the gage reads deviation from zero. So you'll need a way to set the gage using either a micrometer or a ring gage. You place the gage in the bore and your rock the gage back and forth slightly to obtain the smallest reading, indicating that the gage is perpendicular to the bore. You might want to use a telescoping bore gage and an outside micrometer to measure the bore diameter. Regardless of which way you use, there is a certain amount of finesse required to obtain accurate and repeatable measurements. I've played with both and the dial bore gage allows quick multiple readings, but you have to make sure that the set diameter is accurate and you have to keep track of the deviations from the set diameter.

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mike_sdak
OK - low tech, but how about a combination of a spring inside caliper (to transfer the measurement), and a good caliper to measure the transferred measurement?? A couple links: http://www.grizzly.com/outlet/Stainless-Steel-Inside-Spring-Caliper-10-/G9272 http://www.grizzly.com/products/4-Digital-Caliper-w-Large-LCD/H8057 I think you would need to take several trials to make it work. Thoughts??

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UCD
A set of inside Mic's would serve you better. http://shop.ebay.com/items/inside%20micrometer?_dmd=1&_sop=12&rvr_id=&MT_ID=69&crlp=2982086646_9399&tt_encode=raw&geo_id=1&keyword=inside+micrometer&adgroup_id=1056342426

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Brettw
Thanks all. I will look at the set of inside mics first. Being the cheap smack that I am, we'll have to see what's available. But thanks for the heads up Maynard.

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rick66
BLT, I saw you made a comment on max allowed gap on the rings. If was to put in a new rings just to check the size of the bore, What is that the maximum gap allowed. Thanks for the great info

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steve-wis
I work in a machine shop, and I would think that if you brought in an engine block and just wanted the bore or bores checked for size, taper, and out-of-round, it would only cost 5 or 10 dollars at most. It would take me about 5 minutes to do that. A bore gauge will be of no use for checking size unless you have the equipment to set it, either an outside micrometer or a set of gage blocks. An inside mic is not as accurate as an outside mic because the stems are changed back and forth, inviting dirt and other problems. They are usually checked with an outside mic if you want an accurate measurement. A spring caliper requires alot of experience to get an accurate size. A telescoping gage is easier to use, but requires an outside micrometer to check it after it is set in the bore. My best advice is find a shop, get a quote and go that way unless you are doing an engine a week or something. As always, only my opinion. Steve

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BLT
quote:
Originally posted by rick66
BLT, I saw you made a comment on max allowed gap on the rings. If was to put in a new rings just to check the size of the bore, What is that the maximum gap allowed. Thanks for the great info
.030" on compression and .035 on oil control. This applies to cast iron blocks and iron sleeves.

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Vassal
quote:
Originally posted by steve-wis
.....My best advice is find a shop, get a quote and go that way unless you are doing an engine a week or something....... Steve
I'm with Steve too unless you plan on doing a lot of this I think you're money ahead with his advice.

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Brettw
quote:
I'm with Steve too unless you plan on doing a lot of this I think you're money ahead with his advice.
Not bad advice at all. My real need to measure was to order the proper kit. Then I would also have the mics for future use. I have honed cylinders before, and if I can simply hone and then fit the new rings I am fine. If it requires machining, it is off to the Pros, no question. I will be doing some checking however, it might just be a whole lot easier to take it in and say "check it out, hone if necessary bore if need be and let me know so I can order my kit". Thanks again everybody, I will update when I finally get my rear in gear! Easy is good sometimes. 8D

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Al
Hi, I would measure it with an inside mic and then measure the inside mic with an outside mic. Measure it 90 degrees to the wrist pin and about 1/2 inch from the top and in line with the wrist pin. Next check the bore at the bottom. I would expect the bottom to have less than .001 or .002 wear, but have seen 1 k 301 that was .026 at the top and was still running. It could not be rebored and we bored it and sleeved it because it would have had to have been bored 040 to clean it. The cylinder wear is mostly on the thrust side and a cylinder worn .010 may barely clean up at 020 for this reason. If the bore is over .003 over, my advice it to bore it. DO NOT UNDER ANY CIRCUMSTANCES TRY TO PUT A 020 PISTON IN A CYLINDER THAT MEASURES .020 AT THE TOP. The bottom of the cylinder will probably have almost no wear. Al Eden

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MrSteele
The only "problem" with the inside mic or a bore gage, is the operator. If the gage is used just a bit improperly, your readings are useless, and you may not know whether you are right or wrong. You can use the gage at a slight angle inside the bore, and your reading is useless. I have the best luck with a caliper and outside mics across the caliper. The bore gage must be used square with the bore, or your reading is wrong. Take the block to someone who uses the tools regularly.

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