Sealed Power piston rings - ignore the dot?


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By peeeot - 13 Years Ago
This is the second time I have encountered this issue. The other time was with a 352 Fe in a '59 thunderbird.



The original rings I removed from my piston are as follows:



1. Top compression ring has a bevel on the upper inside edge

2. 2nd compression ring has a dot on top and a bevel on the lower inside edge



This is consistent with all 8 pistons.



The Sealed Power cast iron ring set differs from the originals; the top ring is the same, but the 2nd compression ring has a dot on top and a bevel on the UPPER inside edge--same as the top ring.



With my '59 T-bird, I went so far as to contact the manufacturer, and they said to go with the dots (install them toward top of piston, regardless of bevels). When I put the engine together, it ran fine, but blow-by was excessive and compression was about 20 PSI lower than it should have been with fresh rings. I do not want a repeat of that scenario if I can help it.



Has anyone else noticed this about the sealed power rings? How should they be installed?
By Hoosier Hurricane - 13 Years Ago
Peter:

Go with the dots to the top.  And don't check the compression right away with new rings, run it about 500 miles and give them a chance to seat.  I take it you have the replacement piston in hand.

By peeeot - 13 Years Ago
Yes sir, I have it, thanks! Interestingly, the rings on that piston did not have any bevels on the inside edges. I don't understand how a design feature like that could be so varied from rings set to ring set without altering the performance of the rings, but then, I don't design them Wink



I'll go with the dots.



By the way, the pin that came with the "new" piston fits looser in the rod bushing than the old one, but the old pin is too tight in the new piston to push in by hand. I'm assuming the best coarse of action is to ream out the piston a bit? I'm thinking it would take well under 0.001".
By Hoosier Hurricane - 13 Years Ago
Sounds like your engine has had the rods and pistons honed for oversize pins to repair worn pins/bores.  Oversizes came in .0015 and .003 oversizes.  You will either have to have the rod rebushed and honed to standard, or have the piston honed to fit the oversize pin.  The latter solution would obviously be the quicker and cheaper method.
By peeeot - 13 Years Ago
It's strange, I measured both pins with digital vernier calipers and kept getting the same numbers, but clearly they were not the same. I was able to hone it and get the pin to fit, just took a little time.



Now I need to get a ring groove cleaner, cause using a broken ring to clean the groove is incredibly tedious!