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Piston Ring Wear: is this Normal?

676 Views 16 Replies 6 Participants Last post by  eutu1960
I am refreshing my 383 sbc tpi with 54000 miles on her she has been getting low on power, I dissembled the engine
and the top rings all have the same wear witch seems excessive to me, the rings were ductile iron and the pistons were Hypereutectic,
is this normal. Thanks for opinions. Also 2 of the rings were broken.
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Discussion Starter · #6 ·
Not enough end gap the ring ends are expanding when hot and butting together pushing the ring into the bore wall which might also be damaged.

Bogie
If you look at the pic's I am talking about the wear on the land area of the ring, the but ends look fine and the cylinder walls look pretty good and only have about .002 to .003 wear at the top of the cylinders.
 

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Discussion Starter · #11 ·
The worn side of the ring....is that the upper side or the downward side??

How does the piston ring land look, on that side was against the worn ring side??
How does ring groove width compare to the ring thickness?

Engine run without an air cleaner??

Engine compression ratio and camshaft specs might be helpful info too.
Worn side is the down side
Piston ring land looks good
engine was run with air cleaner
cam is .480 lift, 210 int./ 219 ext. 112 lsa
comp. 10.42
no signs of detonation on pistons that I see, I will take a pic
it's hard to tell ring fit in land with the ring worn, I will be replacing pistons.
here are some pics of piston with unbroken ring and pics of piston with broken ring,
 

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Discussion Starter · #13 ·
What brand pistons are they? I don't know about others, but K-B hypers place the top ring closer to the top of the piston, so they get hotter and require a larger gap. As I recall, K-B recommends .026" for a 4" bore (normally aspirated), instead of the more common .016". Some folks have been known to ignore this, for whatever reason, but they are flirting with disaster.:oops:
Pistons were Sealed Power, If I remember the pre gap rings were more over .020, that was back in December of 2015 so I am really not sure.
 

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Discussion Starter · #17 · (Edited)
1st post says "383 TPI" so I"m assuming iron heads??
At 10.42:1 compression with relatively short cam and restricted intake it can lead to detonation.

what do the upper halves of the rod bearings look like??

Pistons just strike me as subjected to repeated levels of mild detonation....
What cylinders had broken rings??.
L98 aluminum heads 113 castings, rod bearings look good, cylinders 3 and 5 if I remember correctly.
 
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