Piston ring clearance

Ross pistons, sealed power rings. The oil rings and 2nd compression ring have .0025 clearance or more in the groove of piston. the top compression ring is so tight cannot get .0015 feeler gauge in groove with ring. can close ring gap by hand and ring still turns freely but ross calls for .001 to .004 has anyone else experienced this and what to do?

Usually Ross pistons come with a QC check sheet (At least the sets I've seen) There should be a dimension for the top ring groove. You should be able to easily measure the ring and see what the gap really is.

Are these gas port pistons? The reason I ask is I've heard that if the ring groove is too tight, the compression has a hard time flowing behind the top ring to seal it...

no gas port and no dimension of top groove. thanks for the reply

Am I missing something or has noone else experienced this?

if ring moves freely,, assemble your motor ring land clearance is usually less than .001 on a top ring,, i usually try for .0006 but i have lateral gas ports

thanks that was my original thought but i have never used ross pistons and my others were not as tight

Take a few of those rings and "mic" the thickness of the RING. Last year I had a set of rings that actually were thicker in some spots than other, binding the ring. Never saw such a thing. Also, make sure there isnt a little burr sticking in the ring groove somewhere. That is actually quite common to find in new pistons.Just a small nail file and its gone, and the rings will float and clearance properly. Double check just in case. Good luck.

What temperture are you checking the ring clearances at? If it is real cold, under 50F the clearances may seem tighter, and they are than they would be at 70F or above. The aluminum piston expands 8 more times than the iron or steel rings, warm the piston up in a oven with the rings on it to 100 F and recheck the feel and actual clearances. I made the mistake of checking a set of piston in my shop in SO CA with half of the pistons sitting in the sun coming thru a window and the other half out of the sun. The air conditioner was on and the room temperature inside was right at 70F, the half of the pistons sitting in the sun light where several thousands bigger in the skirt than those that where out of the sun I finally figure it out and moved them all out of the sun light and remeasure them two hours later and all of them where within .0003 of each other. I have had a set of rings like BG has noted, very frustrating, one of the reasons you have to check parts when they don't seem right, when in doubt, check it out BTW, I like tight ring lands(.0008 to .0012) on a race motor in normal room temperatures

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Ross pistons, sealed power rings. The oil rings and 2nd compression ring have .0025 clearance or more in the groove of piston. the top compression ring is so tight cannot get .0015 feeler gauge in groove with ring. can close ring gap by hand and ring still turns freely but ross calls for .001 to .004 has anyone else experienced this and what to do?

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My venolia forged pistons require 3 to 4 thou ring side clearance,going buy there recomendations.