My pistons are marked .030 and Stamped with the letter M with a square around it. 2 questions. Are these Pistons made by Omc? If they are then can I use Pro or vertex rings on them?
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My pistons are marked .030 and Stamped with the letter M with a square around it. 2 questions. Are these Pistons made by Omc? If they are then can I use Pro or vertex rings on them?
Those are OMC pistons. Yes, the Vertex rings will work, Vertex usues the OE ring configuration.
Just make sure you follow the re-assembly rules with piston facing the exhaust ports.
The compression is 85 p.s.i. on that one compared to 120 on the others. Can I change just the rings on that one or do I have to replace that piston?
Is the motor torn down? Piston scuffing, damage to the cylinder? If so and it is orignal an .030 bore is accepatble and adding .030 oversize is fine. If it doesn't fall into spec then you need to re-sleeve the block on the offending piston. STD is fine, just when the sleeve is installed you have if honed, not bored. Get a standard piston set.