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tobski

cant find .010 rings, file .020 down? ever done?

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tobski
Can .020 rings be used in a .010 bore if the ring end gaps are filed down? This is not something I would want to do by choice..This seems to be my only choice in putting new rings in, or else I'll have to bore to next size larger, which right now, my bore is good and smooth at 3.07....or just use same rings I took out, and dont hone. THe man at machine shop and I both question the gap between the piston and cylinder walls, any specs on what it should be? I cant find it. Thanks in advance


I just used a clean red rag inside cylinder, left some fibers on it




The piston is .010 over


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Mel_W
It doesn't really matter what the specs are you have to get it to fit what ever size you bore it or hone it to. I've honed .010 it takes a while but it works. you can knurl the piston skirt then file fit the rings. Mel

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dhardin
These are the times I miss my dad the most. If I remember right to gage the ring gap clearance. For every inch in piston width you need .010 for heat expansion. So 3" position =.030 clearance a 3 1/2 piston = .035 . I may be wrong, take out to much you loose compression and use oil. To little taken out you will score the cylinder and potentially brake the ring when it expands.

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Al
HI, I used to have an air operated knurler for pistons. I sold it, If you knurl a piston for more than .003, you risk having a piston fail. At .010, you are building stresses in the piston that are asking for fsilure. All manufacturers stress rebuild at 003 or less with a rebore and oversize piston.a Knurling was developed for the auto industry when ring jobs were the common way. Knurling was to deal with clearances up to .003 in water cooled engines that have cylinder temps in the 180 to 200 degrees in the old days 16 0 to 180. In air cooled engines the temps get up to 500 degrees. I think knurling to .010 over is asking to construct a block with the observation or inspection opening to observe the insides when the skirt comes off and makes the rod break and open the inside to the outside world. Our company would never accept the liability that travels with this. Al Eden

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Johnrenk
Maybe replace the piston and rings, check out of round, there are some pretty good scratches in the wall, just rings will not satisfy your need. I just did a 50 year old engine their was more ware on the piston than anything else.

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1Litre
.004" for every inch of bore diameter. You 3.07" bore would be .012" ring gap. Briggs rings are on the loose side and you would see .020 or more with new rings for the size bore they are intended worn or not. Check the ring groove clearance with the ring installed. .004" is ideal but if you get up around .008 the piston should be replaced. Hastings makes a ton of ring sizes that you can look up online. I made a Kohler 14 .040 over using their rings. Ordered direct with credit card and had them in two days. You may find .010" rings from them. I have put .010" in std. bores many times but I do not think I would try .020" Ken

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powerking_one
Tobin, Looking at the pics, I'd say you or the previous owner had/has been running dirty oil causing the scuffing on the piston skirt and cylinder walls. Also, Dan (dhardin) is off by an order of magnitude with piston to wall clearance. The rule of thumb for air cooled engines is .001" for each inch of bore diameter, not .010" as he stated. Yes, I have taken say .020" rings and filed them down for a .010" bore with fine results,just as others have said,but be carefull and keep the ends square checking with the feeler gauge frequently. I would highly recommend NOT trying to knurl the piston in attempts to compensate for wear. Looking at the forementioned scuffs/scores, I'd pursue boring it to .020" and a new piston/rings to do the job "right". Also with this kind of wear, how's the crank journal in terms of wear and scoring? Tom (PK)

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BLT
quote:
Originally posted by powerking_one
Tobin, Also with this kind of wear, how's the crank journal in terms of wear and scoring? Tom (PK)
Tom here is the thread on the rod. http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=120145

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Al
Hi, The spec on the Briggs is 010 on new and max 030 used. Roughly .003 per inch of bore new and NMT ,010 per inch of bore is good rule of thumb. Kohler spec is almost exactly the same for cast iron. Aluminum specs are some different. If you have a .020 over ring and need to use it in a .010 cyl you could file it with out a problem. To file the rings, put the end of a file in a vise. Then take the ring and draw it to you with the inside of the ring toward you and the outside toward the end of the file. This way with one end of the ring in each hand as you press the ends against the file you file from the inside out. If you try to file from the outside in the gap will wedge against the file teeth and you will usually break the ring, as will trying to file sideways. You will be filing both ends of the ring with each stroke. Al Eden

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RayS
The guy in the link below had a coil that I could not find anywhere else and has lots of parts for these old engines. The briggs number should be 299090 for the rings and Sears says they have them for $43.00 may be old stock. Below is a set on ebay. http://www.ebay.com/itm/Briggs-Stratton-Small-Gas-Engine-Piston-Ring-set-299090-New-3-4-5-6-7-8-9-10-/290666007176?pt=LH_DefaultDomain_0&hash=item43ad0b4a88 http://www.bser.com/ If you need the parts manual send me your email address and I will send it to you.

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