Broken ring lands

crazycuda · Post by **crazycuda** » Thu Aug 17, 2006 8:33 pm

I tore down a 327 sbc today that had only 5k on it. The motor was smoking out the right bank like a freight train but allin all surprisingly ran smooth . Another shop did the motor (who has a ok rep) so I wasn't expecting any major surprises but the customer wanted a full teardown. Anyhow 4 pistons on the right bank had all of the oil ring lands broken downward and 2 of the pistons had the land between the top and compression rings busted also. You can guess the block in in need of replacement, (it was punched .060) any ideas on what could cause such a mess. The left bank was perfect not even a scuff on the skirts.

MadBill · Post by **MadBill** » Thu Aug 17, 2006 9:09 pm

Their apprentice installed the right bank pistons maybe, and used too big a hammer?

greasemonkee · Post by **greasemonkee** » Thu Aug 17, 2006 9:20 pm

When I hear the words "broke ring land", detonation pops into my head for some reason...

MadBill · Post by **MadBill** » Thu Aug 17, 2006 9:23 pm

Yesh, but the oil ring lands?

beth · Post by **beth** » Thu Aug 17, 2006 9:26 pm

MadBill wrote:Yesh, but the oil ring lands?

I agree Bill. Did someone use a ring compressor for a bit larger bore on that side? Do the bore chamfers look the same bank to bank?

jdeleon · Post by **jdeleon** » Thu Aug 17, 2006 9:39 pm

Check for ring butting.

awesomebill · Post by **awesomebill** » Fri Aug 18, 2006 6:53 am

crazycuda wrote:I tore down a 327 sbc today that had only 5k on it. The motor was smoking out the right bank like a freight train but allin all surprisingly ran smooth . Another shop did the motor (who has a ok rep) so I wasn't expecting any major surprises but the customer wanted a full teardown. Anyhow 4 pistons on the right bank had all of the oil ring lands broken downward and 2 of the pistons had the land between the top and compression rings busted also. You can guess the block in in need of replacement, (it was punched .060) any ideas on what could cause such a mess. The left bank was perfect not even a scuff on the skirts.

The right bank always gets the detonation factor first, but I think this was a rich condition with a cheaper piston. I have seen the cast pistons break the ring lands out with just minimal detonation or ping. What piston was it? Race or stock? I do not think or believe someone broke all the rings on assembly. That is nonsense. You would have seen this on start up, even if it would. Did the customer have a little NOS hanging around you did not know off. The ring pinch would pop the top out not break the ring lands out. Any black marks on the sides of any of the pistons center of the skirt? With the oil being thrown up on that side, which is indicitive of the engine design, will help unload the rings faster. What gas or compression was he using as well. Just some thoughts. As always, he was just riding down the road cruzin when it just happened.

Ron E · Post by **Ron E** » Fri Aug 18, 2006 11:14 am

awesomebill wrote:
crazycuda wrote:I tore down a 327 sbc today that had only 5k on it. The motor was smoking out the right bank like a freight train but allin all surprisingly ran smooth . Another shop did the motor (who has a ok rep) so I wasn't expecting any major surprises but the customer wanted a full teardown. Anyhow 4 pistons on the right bank had all of the oil ring lands broken downward and 2 of the pistons had the land between the top and compression rings busted also. You can guess the block in in need of replacement, (it was punched .060) any ideas on what could cause such a mess. The left bank was perfect not even a scuff on the skirts.
The right bank always gets the detonation factor first, but I think this was a rich condition with a cheaper piston. I have seen the cast pistons break the ring lands out with just minimal detonation or ping. What piston was it? Race or stock? I do not think or believe someone broke all the rings on assembly. That is nonsense. You would have seen this on start up, even if it would. Did the customer have a little NOS hanging around you did not know off. The ring pinch would pop the top out not break the ring lands out. Any black marks on the sides of any of the pistons center of the skirt? With the oil being thrown up on that side, which is indicitive of the engine design, will help unload the rings faster. What gas or compression was he using as well. Just some thoughts. As always, he was just riding down the road cruzin when it just happened.

bill, years back I had a guy almost cut his pan in half while at idle at a traffic light.

Ed-vancedEngines · Post by **Ed-vancedEngines** » Fri Aug 18, 2006 1:00 pm

I think that possibly Frazy Cuda has made a mistake in explaining the problem.

The oil ring land on the bottom is the cotten picken piston at the wrist pin on that size engine. It is very beefy in that spot. On the top it is also still very beefy there. I would think that would be the hardest part of the piston to break. I can not possibly understand how the downward part of it can break. It is solid there.

I think that I must not be understanding this desription correctly?

Any pics of them?
Ed

crazycuda · Post by **crazycuda** » Fri Aug 18, 2006 5:47 pm

Ed-vancedEngines wrote:I think that possibly Frazy Cuda has made a mistake in explaining the problem.

The oil ring land on the bottom is the cotten picken piston at the wrist pin on that size engine. It is very beefy in that spot. On the top it is also still very beefy there. I would think that would be the hardest part of the piston to break. I can not possibly understand how the downward part of it can break. It is solid there.

I think that I must not be understanding this desription correctly?

Any pics of them?
Ed

I'll try to explain a little better. First the pistons are sealedpower stock replacements. If you can invision a piston being installed upside down with just the oil ring and someone were to beat the piston in the hole. The area at the piston(where the pin is) that is the thinnest is broken out on both sides of the pin. It broke downward twords the skirt. The other ring lands that were broken on 2 of the pistons is between the to rings. The rings are to messed up to tell if the ends butted up.
If someone has a picture posting site or can rsuggest one i'll take some picts and upload them tonight. Hopefully that will help my explination.
John

awesomebill · Post by **awesomebill** » Sat Aug 19, 2006 8:22 am

crazycuda wrote:
Ed-vancedEngines wrote:I think that possibly Frazy Cuda has made a mistake in explaining the problem.

The oil ring land on the bottom is the cotten picken piston at the wrist pin on that size engine. It is very beefy in that spot. On the top it is also still very beefy there. I would think that would be the hardest part of the piston to break. I can not possibly understand how the downward part of it can break. It is solid there.

I think that I must not be understanding this desription correctly?

Any pics of them?
Ed
I'll try to explain a little better. First the pistons are sealedpower stock replacements. If you can invision a piston being installed upside down with just the oil ring and someone were to beat the piston in the hole. The area at the piston(where the pin is) that is the thinnest is broken out on both sides of the pin. It broke downward twords the skirt. The other ring lands that were broken on 2 of the pistons is between the to rings. The rings are to messed up to tell if the ends butted up.
If someone has a picture posting site or can rsuggest one i'll take some picts and upload them tonight. Hopefully that will help my explination.
John

Just as I thought, he was sitting at the traffic light when this one happened also. I will have to remember that one.

peerless · Post by **peerless** » Sun Aug 20, 2006 8:34 pm

I might be wrong but on a SBC, dont the rods have oil squirt holes? Is it possible the rods where hung backwards and there was no oil getting to the cylinder walls/piston causing a overheating of the piston.

Would this cause the rings to expand enough to butt up against each other enough to cause serious failure as descriped??

Just a thought

crazycuda · Post by **crazycuda** » Mon Aug 21, 2006 1:59 pm

I uploaded some picts on yahoo hopefully it worked

http://pg.photos.yahoo.com/ph/cudaboy66 ... r=/57b3re2

Ed-vancedEngines · Post by **Ed-vancedEngines** » Mon Aug 21, 2006 2:33 pm

Johnnie,
I think that I also see a lot of scuffing on the skirt of them too.

I am wondering if maybe they experienced some severe heat which could have made the casting easier suseptable to damage from the added pressures of the piston expanded.

I have seen lands broken and partially broken on stock or cast pistons. I have also seen them partially broken which can cause them to initially look as if they are bent either up or down.

This is another one of those where I can only be guessing.
Ed

DCal · Post by **DCal** » Mon Aug 21, 2006 9:03 pm

Any chance the other shop used up 4 pistons learning how to press the pins and rods together?

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Broken ring lands

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