20 Lubricate the piston and the piston rings with engine oil. 055) We have recently put into production a. Be careful not to stretch the ring too much or you will break it. 1: force piston question: 2: Force 125hp Tilt Cylinder piston: 6: 1994 Force Mercury 90 hp piston ring info: 12: 1985 85 hp force blown piston and rebuild: 0: 1992 70 hp force piston: 2: 1992 70 hp force piston: 1: 125hp force piston rings: 2: 1983 force. This chart will help illustrate the minimum ring end gaps:. Using a feeler gauge, file the piston ring to meet the. piston rings. Last time I put the 2. The major thing is that none of them line up. (1] The oil expander ring gap is positioned opposite the piston thrust side. Make sure the end gap is loated around the locator pin as shown. Federal-Mogul piston rings for large bore engines have exceptionally good durability. air to clean the inner surface, before putting the piston rings in it to compress them. See orientation diagram. • Position the end gaps of the three piston rings as shown in the figure. Homelite Piston Rings. Position end gap of oil control ring on opposite side of piston from oil ring expander gap. the inlet side). Re: Best Piston Ring Position ? On a 3 piece oil ring I would put them in very similar to the chart you posted. The taper face ring provides good oil control by scraping the cylinder wall. Lower quality pistons can have variations in the cut, which will reduce the effectiveness of the rings to properly seal in the cylinder. If you use the top of a worn bore to set the end gap, the end gap will be too small when the piston reaches the bottom of the bore. When you check ring gap use the piston to press the ring down into the cylinder which will give you a proper gap. A difference of. ), number, or letter that will aid in determining which side of the ring will face up toward the dome of the piston. Also, note the depression between the top and second ring on the piston to the right. Yes over 13 is not good. 1 Chrome Compression Ring (Ring Gap:. The most critical thing to check when installing piston rings is the end-gap. There is no need to off-set the ring gaps, this is an old wife's tale. Piston ring orientation I replaced the piston rings in my 4HP Briggs and Stratton (Model 122702, Type 311701, Code 91031356) and forgot to note how the rings were oriented around the piston head. 003” (see fig. If the ring finds itself in this position it expands outward and the piston breaks it off when it passes the top of the port. Using a feeler gauge, file the piston rings to meet the manufacturer's specifications. install piston rings on piston per installation instructions included in ring set. I understand that the oil ring should be at 12:00 straight up, but the oil ring I have is a 3 stage thing with three rings not one, same as what was on the engine previously. End gap is the clearance between the two ends of a piston ring as it is installed in a cylinder (fig. oversizes to provide correct tolerances when cylinders. The ring end gaps will align with one another at random intervals during engine operation. Ring Lands / Ring Grooves - These are the grooves cut into the side of a piston that the rings sit in. It takes a little wiggling finessing to get the three oiling rings in their gap, but it will and must sit in there with all the outer edges of the rings flush to each other and to the piston side ring land surface. Note 2: Since a cylinder set code (Y-) represents a piston ring set for only one cylinder, an engine requires a cylinder set multiplied by the number of cylinders of the engine. Oil ring does not appear to have any bevel or dots. ; Repeat steps 39 through 46 for the remaining pistons. To find the proper ring end gap, multiply your bore size by the ring end gap factor listed on the chart (i. Get This Wrong and You'll Destroy Your Engine! | Piston Ring Gaps [FREE LESSON] - Duration: 17:26. The end gap of the second ring should be at the 6 o'clock position. Anyone have any thoughts on the "correct" gap spacing for piston rings? Assuming newly honed sleeves, new pistons & rings, all within spec and one piece oil ring. In the absence of specific manufacturer's instructions, the oil ring-spreader gap should face the nonthrust side of the bore, with the upper and lower rail gaps alternately positioned approximately 1 1/2 inches to either side of the spreader gap. Use of his brainchild revealed that some gas did get through the top ring gap sufficient to generate a hell of a pressure between the top and second rings – so it clearly was not finding the gap in the second ring. The broken piece may cause further piston or engine damage. ENNYWHO, ring end gap is highly over rated as to the cause of blowby or oil burning. The number of rings in the ring pack depends on the engine type, but usually comprises 2'4 compression rings and 0'3 oil control rings. The radial pressure of the ring tension is only used to START the sealing process, and cylinder pressure is what really pushes the ring outwards against the cylinder wall. Position the piston ring then turn the handle to rotate the abrasive wheel. While the primary dynamics (i. cast aluminium), a bushing may be used for the pin. Using a feeler gauge, file the piston rings to meet your needs. Step 2: Piston rings come as a set wrapped in plastic and shipped in boxes. if i were to do a compression test and got seriously good compression does that mean the rings are bed in? if yes , why do any more hard driving when not needed ?. Piston rings have a gap so that they may be installed into the piston grooves and removed when worn out by expanding them. Use the piston ring remover tool to install piston rings. positioned so that the piston does not rest on the ring gap. The rectangular and the barrel face are the most commonly used top compression rings because they provide the best seal. They did tests where the rings were locked in line and the engine dynoed with no oil consumption. 004 inches times the bore diameter for the top piston compression ring. The end gaps of the scraper rails were within spec from the factory so I was able to move right into installing the oil rings. Ring gap in a worn cylinder is normally greater than specification. Similarly place and slide the first ring into the piston. com to help other shoppers, like you, with their purchasing decisions. The ring end gaps will align with one another at random intervals during engine operation. 016 on the top and second ring at that same location in the bore. Position the rings so the gap of each successive ring is on an alternate side and the gaps are in line with the piston pin bosses. Step 1: Installing piston rings sounds like it should be a box-to-piston process, but there is more to it than that. M Tap the piston into the cylinder with the wooden end of a hammer. With the oil control rings loaded on the piston, using a proper ring installation tool, open the second groove rings with the top mark up, just enough to allow the ring to go over the top diameter of the piston. Check each ring in its corresponding piston groove to ensure proper axial and radial clearance. Rotate cylinder 2 full turns this will help to line ring up. Oil consumption is found to vary with ring position and, where the rings rotate periodically, the rate of oil consumption is a function of the rotation period of the rings. 020 oversize have a ring gap of. work basically in the same way. the instructions on the ring box say to not align the gap with the wrist pin or the thrust side of the piston and for the oil rings it says to place the top & bottom cap rings @ 45 degree's to the oil ring. Fuel line plugged or kinked. Take the plastic removal ring from the seal kit: a) Straighten the ring and remove any kinks or excessive curl to make installation easier and prevent it from falling out. If the gap is too narrow (less than the minimum recommended clearance), the ends of the rings can be filed to increase the gap. Piston Ring Installation c. which way should the piston ring end gaps should face? the cylinder wall is constant throughout the stroke of the piston. A difference of. The MB shop manual specifies gap clearance of piston rings and side clearance. The end gap is the distance between the open ends of the ring when it is inserted in the bore in its normal position, but without the piston. Piston rings can be damaged during installation if the lower lip of the ring compressor is nicked. Supercharged and turbocharged engines tend to do this to protect the rings from excessive heat. You have to be careful with the expander since the ends tend to overlap. While the primary dynamics (i. Keep in mind that the rings can only go on one way due to the ring end is grooved to fit. Gap position of the top compression ring has been shown to affect hydrocarbon exhaust emissions, and alignment of ring gaps is thought to cause an increase in oil consumption. dynamic seal may be due to piston ring end gap alignment or by the piston and piston rings angular direction in the cylinder bore see Figure 4. Oil the piston and rings and stagger the ring gaps. But there is a lot more to this than may first meet the eye. Before I get started. 025" two ring piston's range from. Place the piston ring in the cylinder. They should also be fitted so that the gaps in the rings are equally spaced around the piston. 0035 gap per inch of cylinder diameter. I put some oil on the piston to help the rings slide into position. With a ring gap of Oh,. Using a feeler gauge, file the piston rings to meet the manufacturer's specifications. Piston ring position products are most popular in North America, Eastern Europe, and South America. Deals on Kimpex Piston Replacement Ring Set Ski-doo OEM# 420815043 #183079! Only $6. Install all the 2nd compression rings then install all the top compression rings last. Setting the correct ring gap on aftermarket piston rings is crucial for proper performance and engine longevity. Piston rings are a major factor in identifying if an engine is two stroke or four stroke. Too big a gap and there will be too much blow-by, too small a gap and the ring will over expand potentially damaging the cylinder bore or the ring landing. Check ring end gap; single ring piston's range from. 004) so I use the flat side of a cutoff blade on my rotary tool. However, piston speeds must be kept low to avoid loss of the mercury seal, limiting maximum flow rates and increasing measurement cycle time. 016" A good way of checking if the gap is correct is to place the ring into the cylinder near the top and measure the gap with feeler blades to ensure it is correct. To assure proper piston ring end-gap, the piston ring filer enables the user to file piston rings quickly and accurately. They are set with precision so as to apply the correct pressure on the cylinder wall or liner, which ensures there is a consistent film of oil across the cylinder's working surfaces. This makes sure that the ring is sitting squarely in the bore. 40 when new and a wear limit of 1. You can ensure product safety by selecting from certified suppliers, including 64 with ISO9001, 12 with Other, and 1 with ISO/TS16949 certification. an inverted position and then. 5% of the piston diameter and can be measured by placing the ring in the cylinder and using a feeler gauge. Another reason for the ring gap is simply because the ring must be split apart slightly in order to facilitate installation. and stagger the upper and lower oil rings also away from where the center piece is located. information, printed on each compression ring (located next to the piston ring gap), is installed facing the top of the piston for both the top (#1) and middle (#2) compression. Three piston rings suggest that it is a four stroke engine while two piston rings suggest that it is a two stroke engine. Position end gap of oil control ring on opposite side of piston from oil ring expander gap. Use of his brainchild revealed that some gas did get through the top ring gap sufficient to generate a hell of a pressure between the top and second rings - so it clearly was not finding the gap in the second ring. regarding orintation in ring groove up/down they can be installed either way because the ring sides are square, rings that are marked have one side tappered or a steped groove to help with compression sealing. Position the piston ring firmly against the dowel pins, and then turn the handle to rotate the abrasive wheel. caterpillar cross reference. Anyone have any thoughts on the "correct" gap spacing for piston rings? Assuming newly honed sleeves, new pistons & rings, all within spec and one piece oil ring. Piston Ring Positioning (Diesel) Refer to "1. Setting the correct ring gap on aftermarket piston rings is crucial for proper performance and engine longevity. Carbide coated steel wheel files the hardest of rings. Using a feeler gauge, file the piston rings to meet your needs. Ring end gap is checked with the piston ring placed squarely in the bore at leas 1/2" into the bore These are what Mikes instructions gave. The G-T® ring cannot roll, twist or spiral (See Fig. Install the compression ring(s) in a similar fashion, lightly applying oil and carefully working the ring around the crown of the piston. aeroflow af98-2108 manual piston ring filer tool - setting piston ring end gap - aeroflow SILVER SEAL 4297 PISTON RING FILER TOOL - FOR SETTING CORRECT PISTON RING END GAP 03 93560173. Suzuki GT/T500 engine tune-up and maintenance details. PISTON RING SET – STANDARD 2-1. Ring to piston groove back clearance should be a minimum of. Piston Ring Installation c. Can someone please tell me how to orient the ring gaps on the piston? I heard that there were locating pins to keep the rings from turning to the ports. 64 000 grain capacity microprocessor based metered water softener. Ring gap in a worn cylinder is normally greater than specification. Piston Rings. The ring gap should be around 0. English US: ZHCN: SYMBOLS “Chomp marks” 切齿标记 “Smushed” 污迹 (forward/neutral/reverse). • 00 not confuse the top and second rings. Ring sets are available to fit standard and over-size pistons. Put rings in a position like you stated with the position to never stacked one on top of. Use of his brainchild revealed that some gas did get through the top ring gap sufficient to generate a hell of a pressure between the top and second rings – so it clearly was not finding the gap in the second ring. Piston ring side clearance is specified in the Table of Tolerances and Wear Limits (page E 95). It is important that the ring end gaps are not lined up. It is my understanding that piston rings rotate frantically in a running engine unless something is preventing their rotation, such as a pin. Should I space gaps at 180 degree, one ring to the next? 120 degrees? Should I keep the oil ring gap be at the back of the block or the front? Top ring any preferences?. 5mm diameter. The piston ring gaps should be situated with the equal. 9 Piston ring end gap positioning diagram. (Most models available from VERTEX, check our catalogue) RINGS INSTALLATION 2 Stroke Engines Minimum Ring Gap Per Inch of Bore inches mm Dirt / ATV / Snow / PWC /Street. This position affects end-gap specs. 1 shows, a properly designed sealing system incorporates some degree of initial O-ring compression. com Crankshaft Balance Factors Crankshaft balancing is the term commonly used to describe changes made in the “counterweights” of the crankshaft (and other components in some cases) to compensate for the weights of the moving components including the crankshaft and the components attached to it (connecting rods, pistons, etc. Normally aspirated drag engines will move the ring closer to the top. When measuring piston ring end gap, check the gap with the rings at the top and the bottom of the bore. 721mm seems huge to me. Worn valve guides Replace engine 4. stagger piston ring end gaps approximately 120 degrees from one another. End gap is the clearance between the two ends of a piston ring as it is installed in a cylinder (fig. Then install the rings on the piston and install it in the cylinder. The quick strategy is to follow your chosen ring manufacturer's suggestions for ring gap sizing. Always use the specs supplied by the piston/ring manufacturer (different thermal properties between different ring materials can even play a role). Move the compression switch to the open position as shown. Honda CG 125 piston rings! The top two rings the same size need to go in the correct way, hopefully they will both have (especially the black one) the word 'TOP' etched on one side. IOW, if there are two compression rings, the gaps will be positioned opposite each other (180 degrees apart); if there are three compression rings, the gaps are. 7 Lubricate the piston and rings with clean engine oil and attach a piston ring compressor to the piston. This allows the piston to build the compression needed for the engine to produce power. Is ring gap orientation really that critical ? in the car the ring gaps were real close to this position. I like to put the compression ring gaps about 10 degrees from the wrist pin ends on opposite sides of the piston and oil ring end gaps 10 degrees on the other side. Install oil ring, 2nd compression ring, and 1st compression ring in order. Autotrol Refill Control. The rate of ring rotation is unique for each ring and the rotation will provide a uniform ring and piston groove wear. Be sure to stagger ring gaps on piston. Rotate the ring so the gap is 180° from the gap in the second compression ring. In this tech article HOT ROD provides a guide to new piston ring technology and takes a look at many of the latest product offerings and provide recommendations for your setup - Hot Rod Magazine. 6L engines Fig. Still the spark plug has a ton of black liquid around it that smells like oil and a mix of gas. Pay attention to position of piston ring gaps (4). Do not align the gaps in the oil rings (side rails). In seeking for the optimum end gap for your particular engine, choose the proper application in the chart and gap the rings to the high limit. Be very careful during this step. The ring gap should be around 0. Its friction is very low and its vapor pressure is acceptable. Modern piston design locates the top ring higher for improved requires a larger top ring end gap. The Rail Rings in the Oil Ring Set should be checked for proper size, but since they can run gaps as large as. The mechanism of piston ring sealing is equivalent to a labyrinth seal, where the gap clearances are determined by the actual position of the rings in the groove in consideration of the global movement and tilting of the piston. Pistons are made to last, but can still fail from other engine issues that may damage the piston or its rings. For a nitrous oxide engine, the top end gap should be opened up even more to. When piston gap is measured in a used bore, it may serve to indicate federal mogul piston ring handbook excessive bore wear or ring wear, or a combination of both types of wear. Use this chart to determine the proper end gap for your engine. staggered correctly, push piston into liner as shown. Move the compression switch to the open position as shown. if i were to do a compression test and got seriously good compression does that mean the rings are bed in? if yes , why do any more hard driving when not needed ?. im going out on a limb here but i think both rings are the same and the thing your calling the oil ring goes on behind the bottom ring. If the bore has taper wear (bores typically wear most at the top), the end gap will be larger at the top and smaller at the bottom of the bore. The other one has no markings. information, printed on each compression ring (located next to the piston ring gap), is installed facing the top of the piston for both the top (#1) and middle (#2) compression. Setting the correct ring gap on aftermarket piston rings is crucial for proper performance and engine longevity. Be sure to stagger ring gaps on piston. Some people like to use assembly lube or two stroke oil to coat the piston and/or rings for this process. No fuel in tank. The inter-ring pressure and piston ring movement were also simulated as a function of ring gap position. A piston ring end gap tool for accurately positioning a piston ring in a cylindrical bore to enable the end gap to be accurately measured and holding the piston ring while filing the ends of a piston ring forming the end gap an equal amount on each end of the piston ring, said tool comprising a continuously cylindrical member of rigid one-piece. This is measured with feeler gauges. This may be accomplished by reducing regulator pressure to 20 P. 2 Picture 3 Picture 1 Suggested ring end gaps Ring. Standard value: No. 006 thats with the ring squared up in the bore at the place of least. When fitting the rings to the piston, position them on the piston so that the gaps are 120 degrees apart. Clean or replace fuel line. Get a real engine builder to do your building your engine so things like this won't cause a failure on your new engine. thermal increase in ring end clearance d. It is my understanding that piston rings rotate frantically in a running engine unless something is preventing their rotation, such as a pin. The gap ensures radial pressure against the cylinder wall thus having an effective seal to prevent leakage of heavy combustion pressure. 2) Series Marks US Application Most of Piston Rings for Gas Engine: Mt. piston position as function of crank angle) is given by the kinematics of the cranktrain, focus of the piston simulation is mainly the determination of the piston secondary motion. Tractor and engine manufacturers will provide tools to place the ring inside and then the ring gap can be measured. Question: “Why are piston rings installed at 120 degrees?” Piston rings are ordinarily fitted to the piston so that, when the rings are fitted into the groves in the pistons, the ring end gaps are spaced and separated evenly around the piston. Piston Ring Gap Orientation - posted in Problems, Questions and Technical: Hi, I have 21253 +20 pistons which have 3 piston rings Just wondering which way should the piston ring gaps be orientated before putting it into the block?. dynamic seal may be due to piston ring end gap alignment or by the piston and piston rings angular direction in the cylinder bore see Figure 4. They are set with precision so as to apply the correct pressure on the cylinder wall or liner, which ensures there is a consistent film of oil across the cylinder's working surfaces. Now that I took the piston back out after running engine. To assure proper piston ring end-gap, the piston ring filer enables the user to file piston rings quickly and accurately. When replacing piston rings, the cost will be determined by several factors. 20! Never pay the full price anymore! Find the best value and the lowest prices on Shopific!. Install the remaining snap ring. A mercury seal also has the disadvantage of toxicity. Other than pinning the piston rings to prevent rotation (which is commonly done in two-stroke engines), there is little we can do to influence ring position or speed of. thrust - LH side of piston - viewed from front of piston. It is probably available on line. Pull the piston out using a small wire or pick. I was taught the spacing should be 180 degrees apart, and the ring gaps were NEVER to line up. A difference of. Service Sheet No. It is my understanding that piston rings rotate frantically in a running engine unless something is preventing their rotation, such as a pin. Compress the piston rings. The gap you have may work but it is not recommended. The KLX110L engine is fitted with a high quality replacable oil filter for a longer engine life. Well, being the piston. First make sure you have them oriented correctly as far as rightside-up. 09/21/16 SEE REVERSE SIDE FOR SUBARU PISTON RING INSTALLATION INSTRUCTIONS PISTON AND RING INSTALLATION INSTRUCTIONS SUBARU EJ20, EJ25, FA20. A difference of. Types of Compression Rings. Yes all 3 oil ring gaps are left of center as is #2. Re: Piston ring gap position? « Reply #1 on: October 19, 2008, 12:09:35 pm » Usually 1 is positioned at 10 oclock and the other at 2 oclock and the bottom oil ring is at 12 is where I put them, thats on the up side of the cylinder. This is measured with feeler gauges. If the ring is not marked on one side near the end gap, either side can be up. I am currently assembling a bmw s50b30us which has been bored over to 86. 3501 West Algonquin Road Suite 850 Rolling Meadows, IL 60008. Much better. If an engine produces white or grey oil smoke or consumes too much oil, it may be a sign of worn piston rings; other symptoms of this problem include poor overall engine performance and a lack of acceleration power. The piston rings may be located in the crown or in both crown and skirt. File fit rings require individual gap adjustments to the top and second rings. 50 mm; if necessary adjust the ring end gap dimension using a file (3). I had to take material off the 2 oil rings,(like. Open the piston box, take the ring and position it inside the cylinder bore. 0065” gap factor =. They say to align the top (fire) ring with the axis of the piston pin, put the second (compression) ring 180 degrees away (toward the other end of the piston pin), and put the oil ring gaps 90 degrees from the axis of the pin. One of my favorite bumper stickers:"If you don't stop tailgating me I'll whip a booger on your windshield" There's room for all God's creatures-On my plate, right next to the mashed potatoes and gravy. Work the opened ring down from the top of the piston to the second groove, place the ring squarely into the piston groove taking care. Normally it is not necessary to modify the ring gap. I like to put the compression ring gaps about 10 degrees from the wrist pin ends on opposite sides of the piston and oil ring end gaps 10 degrees on the other side. Description: To assure proper piston ring end-gap, the piston ring filer enables the user to file piston rings quickly and accurately. One can make own decision for repairing. Hemi ring gap position? Pinching ring lands, melting piston tops and welding rings to the land are three ways that I have been successful in the past. Left Piston Showing Ring Gap Position for Top and Middle Ring His advise is to keep the gaps away from the the thrust side of the piston and the gaps on the left and right pistons are at slightly different clock positions (I provide the positions in the write-up). Try to open the ring as little as possible. There is never a time in which. Install oil ring, 2nd compression ring, and 1st compression ring in order. if i were to do a compression test and got seriously good compression does that mean the rings are bed in? if yes , why do any more hard driving when not needed ?. I will leave it to the experts to comment on the numbers. They impact combustion sealing, oil control, friction, and many more engine attributes. 1st Oversize Piston Ring Set + 0. But there is a lot more to this than may first meet the eye. Regarding gaps, i like to have no gaps on the thrust side of the piston (i. Position the ring in such a way that the oil-control ring gap rests at 180 degrees from the compression ring gap. With the head in place, dip the head bolts in clean oil and install each one for a total of 17 (that is on a small block chevy). Side clearance was. Free gap is measured when you take the rings out of the box and lay them on a table. Each gap on the oil ring package (includes expander and set of upper and lower scraper rails) should be positioned 120 degrees away from each other. Our rings are designed to fit a piston for a standard bore. 026 (forget the percentage these figures equal to over stock gap). See table below for proper ring end gap for your application. Then next ring. Piston ring gap is a word many enthusiasts know about, but few understand. Motorized Bicycle Engine Kit Forum. This position affects end-gap specs. Measured the ring end gap with drill bits as feeler guage as none of my normal ones were thick enough. No fuel in tank. :msp_confused: End gap was 5/64". If all rings, on a tested piston, are above that hole, then the oil should stay in cylinder a long time but it will eventually drain past rings, even if they are good. The dot on the second compression ring must face upward. Here is a quick glance at the oil control. about the mounting position of the piston rings. 50 mm; if necessary adjust the ring end gap dimension using a file (3). Using a feeler gauge, file the piston ring to meet the manufacturer's specification. Below and Following Are Pages For Piston Oil-Ring Groove Clearance and End Gap Visual inspection only Piston Pin O. Re: Kf82 ring and piston job 98 psi was the pressure a lot better that I thought it would be. Use the bottom position to set the end gap. Non-premium engines use pistons with cast iron domes and skirts and open-end connecting rods. position piston and rod back in cylinder and use butt end of a hammer handle to knock the piston and rod back into place. To assure proper piston ring end-gap, the piston ring filer enables the user to file piston rings quickly and accurately. You can see complete sketch above. and stagger the upper and lower oil rings also away from where the center piece is located. Other than pinning the piston rings to prevent rotation (which is commonly done in two-stroke engines), there is little we can do to influence ring position or speed of. Measure the piston ring’s gap. Do not overlap the ends of the oil ring expander. installed with the flow direction over the plug. Finally, use a glaze-buster on the bores before rebuilding. Piston Rings for MC Engines Upper piston ring with double-lap S-seal and 6 Controlled Pressure Relief (CPR) gaps Even heat distribution on 2nd piston ring 2nd, 3rd and 4th piston rings with oblique cut ring gaps New piston ring material: RVK-C for 70-26 cm bores and RVK-C with Alu-coating on 98-80 cm bores When the liner is equipped with PC ring. Re: Kf82 ring and piston job 98 psi was the pressure a lot better that I thought it would be. The gap in the piston ring needs to align with the pin in the piston. If the gap exceeds the service limit, replace the piston ring. Remove all the rings from #5 piston. As suggested above, insert a ring into a cylinder and then, with a piston, push it into the cylinder making sure the ring is squarely inserted (same distance from the top edge of the cylinder. Because piston rings need to be expanded to fit over the diameter of the piston itself before they find their home in the ring grooves, they have to be split in some way in order to allow installation. Then, measure the end gap with a feeler gauge. The same does if the rings have a beveled edge. To be effective, the proper ring gap is more dependent on what usage the engine will see rather then on the rings themselves. 5% of the piston diameter and can be measured by placing the ring in the cylinder and using a feeler gauge.