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Thought you all might find this interesting. These are new rings from Egge Machine vs NOS rings, for a 320 V8.

The top ring is similar in cross section but does not have a double beveled outside edge. The original is chrome plated, and the new one is moly coated.




The second rings appear to both be Ferrox treated, but the lip has moved from the inside top to the outside bottom. I have no explanation for this change. Before you ask: yes, they are both right side up.




The oil scraper rings are unsurprisingly not terribly different in general construction. The old one has some purple paint to help tell if it's overlapped. The new one has these plastic inserts.




And for you packaging nerds, here's all the original packaging.

I wonder if there are any differences in the pistons that Egge produces that led to the difference in rings they selected.

Are you going to go with the full set of Grant rings or do 7 and 1?

Those look like the same Grant rings that Kantar sent me for my 327 last year.

When I showed them to the engine builder that helped me with my project, he was very impressed saying they were the same design as the Hasting rings that they use in their high performance builds. He said Grant must have stepped up their game and that he would be considering trying some Grant rings for future builds.

I had a set of NOS rings and my engine builder said they would be okay, but that ring technology has advanced significantly over the past 7 decades and that he would not use NOS rings.

My car is pretty stock, but there is a little new tech, such as, the rings, coated pistons and some LED lights.

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I suspect it's just more advanced ring technology, and not related to piston design.

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Pretty sure they are just using what they can get. In another thread Jack Vines talks about how they are slightly different such that you can use these rings on an old piston but not NOS rings on a new piston made properly for the new rings.

Edit: see my comment directly below.

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I'm going to use all new rings not NOS, since the two types break in at different rates. The moly helps to give a very fast break in. The owner's manual gave a 250 mile break in period and speed limit of 50 MPH (1800 RPM or so), which cars of today do not need. The other main differences for lack of break in on a new car engine are lower tension rings and much better oil. On a rebuilt old engine the break in period still exists obviously, but is not going to be as severe.

FYI in the 40's and before, when ZDDP and other such "boundary" lubricants were added, break in periods were even longer. I believe a '41 Chevy was:
- 35 MPH max for 250 miles
- 45 MPH max next 250
- 55 MPH max next 500

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I know Egge pistons aren't really the same as Packard pistons. They are just close enough in all important aspects to work. For example the weight is noticeably different.

One difference is that they use D-wall rings not K-wall. The D ring width is dia / 22 vs. K's 20, so K is thicker. Hence you can use the former in a piston designed for the latter (which is what we all do) but not vice-versa.

Jack's comment here explains it well:packardinfo.com/xoops/html/modules/newbb ... 1490&post_id=119406#forumpost119406

The expansion is also different. For example, I talked to Parker Roaf. Egge pistons need 3-3½ thou clearance when new. Ross racing pistons, 2. NOS, 1-½.