Piston to bore clearence is 2th.
Ring gap is 22th.
Yeah, i reved it, but i told the builder it was going to be.
Its a meat pie 355 with harrop crank and vn rods.
My piston has broken ring glands.
Started by
_v8slrtorana_
, May 20 2007 02:41 PM
22 replies to this topic
#1
_v8slrtorana_
_v8slrtorana_
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Posted 20 May 2007 - 02:41 PM
Why would this happen.
Piston to bore clearence is 2th.
Ring gap is 22th.
Yeah, i reved it, but i told the builder it was going to be.
Its a meat pie 355 with harrop crank and vn rods.
Piston to bore clearence is 2th.
Ring gap is 22th.
Yeah, i reved it, but i told the builder it was going to be.
Its a meat pie 355 with harrop crank and vn rods.
#2
_dave720gtr_
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Posted 20 May 2007 - 03:00 PM
detonation is the likely cause by the looks of that i have see it all to often
with todays fuel and to much compression
with todays fuel and to much compression
#3
dattoman
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Posted 20 May 2007 - 03:18 PM
Ping ping ping
Richochete Rabbit
I had 4 like this in my 4 cylinder race engine after 12 laps
Richochete Rabbit
I had 4 like this in my 4 cylinder race engine after 12 laps
#4
_dave720gtr_
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Posted 20 May 2007 - 03:36 PM
Alot of the time in a v8 you carnt hear them rattle over the engine noise ! by then
its to late,
its to late,
Edited by dave720gtr, 20 May 2007 - 03:37 PM.
#5
_82911_
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Posted 20 May 2007 - 06:18 PM
Can we see a pic of the piston crown(top) please...
at the moment it looks to me like your rings have butted.....
there is no way they would have done that at .022" but were they really .022"???
Need a pic of the piston crown to be sure.
Cheers Greg..
at the moment it looks to me like your rings have butted.....
there is no way they would have done that at .022" but were they really .022"???
Need a pic of the piston crown to be sure.
Cheers Greg..
#6
_v8slrtorana_
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Posted 20 May 2007 - 06:59 PM
I measured the ring and piston gaps myself with feelers. Im not relying on what have been told.
Piston was not cleaned for pictures.
Only did a leak down test after removing the the heads.
Piston was not cleaned for pictures.
Only did a leak down test after removing the the heads.
Edited by v8slrtorana, 20 May 2007 - 07:01 PM.
#7
dattoman
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Posted 20 May 2007 - 07:03 PM
How old is the engine and what carb ?
#8
_82911_
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Posted 20 May 2007 - 07:39 PM
Those Pistons are KB silvolites, right?
If so how old are they?
There was a bad batch around some time ago, although I'm sure it was years ago not months ago....
If it wasn't a fault induced structural failure of the ring lands then I'm going for a butted 2nd ring........
there is no real signs of severe detonation there....sure there is the odd speckle but nothing too bad that would shake the piston to bits. when they are real bad it usually looks like the piston has ben sand blasted!
There is SOME oil contamination but again not too bad.....
Looks like the ring seal was decent.
piston to bore also looks ok FROM WHAT I CAN SEE OF THE SKIRTS...
How was the rod bearing on that journal?? any spots on it? or slightly out of round?
Cheers Greg..
If so how old are they?
There was a bad batch around some time ago, although I'm sure it was years ago not months ago....
If it wasn't a fault induced structural failure of the ring lands then I'm going for a butted 2nd ring........
there is no real signs of severe detonation there....sure there is the odd speckle but nothing too bad that would shake the piston to bits. when they are real bad it usually looks like the piston has ben sand blasted!
There is SOME oil contamination but again not too bad.....
Looks like the ring seal was decent.
piston to bore also looks ok FROM WHAT I CAN SEE OF THE SKIRTS...
How was the rod bearing on that journal?? any spots on it? or slightly out of round?
Cheers Greg..
#9
Struggler
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Posted 20 May 2007 - 07:51 PM
I'm with Greg. Normally with detonation you will see heaps of peppering on the crown, and the top ring land will be the broken one.
Yes it does look like a KB, and if that is the case 0.022" is not enough of an end gap, it does look like the rings have butted.
Can you find the missing pieces of second ring (so we can see the ends)and clean off the top of the piston so you can read the part No. This will tell us if it is a KB and which one.
Yes it does look like a KB, and if that is the case 0.022" is not enough of an end gap, it does look like the rings have butted.
Can you find the missing pieces of second ring (so we can see the ends)and clean off the top of the piston so you can read the part No. This will tell us if it is a KB and which one.
#10
_v8slrtorana_
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Posted 20 May 2007 - 08:00 PM
Piston brand unknown. Maybe federal-mogul.
When the egine was built i was told he was going to fit ACL, but he didnt, i just cant remember what went in.
They are cast pistons thats for sure.
Engine was built mid last year.
Its about 2000 kays old.
Hmm, funny you mention the bearing. It is spotted, and was running heavy (bearing marks) around one of the rod bolts.
I will try to get up pics in the next couple of mins.
Enigne is 355 harrop crank, VN rods, crane 288 cam, MDemon 750, crane HI-6. I did lean it when i first built it, then quickly changed the entire fuel system to cope.
Maybe its my fault, im just trying to figure out why, if thats the case.
When the egine was built i was told he was going to fit ACL, but he didnt, i just cant remember what went in.
They are cast pistons thats for sure.
Engine was built mid last year.
Its about 2000 kays old.
Hmm, funny you mention the bearing. It is spotted, and was running heavy (bearing marks) around one of the rod bolts.
I will try to get up pics in the next couple of mins.
Enigne is 355 harrop crank, VN rods, crane 288 cam, MDemon 750, crane HI-6. I did lean it when i first built it, then quickly changed the entire fuel system to cope.
Maybe its my fault, im just trying to figure out why, if thats the case.
Edited by v8slrtorana, 20 May 2007 - 08:07 PM.
#11
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Posted 20 May 2007 - 08:36 PM
What heads ? (trying to figure comp)
Why didn't you deck the block ? Look at those ugly marks between bores !!!
Is that 060 over ?
Why didn't you deck the block ? Look at those ugly marks between bores !!!
Is that 060 over ?
#12
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Posted 20 May 2007 - 08:38 PM
And its ring LANDS
#13
_v8slrtorana_
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Posted 20 May 2007 - 08:54 PM
I dropped all the bits off when i got it back it was a short motor. Thats what i paid for.
Told the builder i was going to off street race it, non competive and do big skids with it.
The head surface, yeah its ugly, but i presummed that was ok, i thought the guy would know what he is doing.
Yep 60th over.
What do you suggest i do.
I have a complete engine that is a virgin bore, but its in my car at the moment. Rebuld that, else where??
Ive never had a engine rebuild before, other then re-ringers which i have always done myself.
Comp is 10.08 : 1 have been running optimax.
The tops of the bores have been shamfered. Incorrect spelling i know.
Told the builder i was going to off street race it, non competive and do big skids with it.
The head surface, yeah its ugly, but i presummed that was ok, i thought the guy would know what he is doing.
Yep 60th over.
What do you suggest i do.
I have a complete engine that is a virgin bore, but its in my car at the moment. Rebuld that, else where??
Ive never had a engine rebuild before, other then re-ringers which i have always done myself.
Comp is 10.08 : 1 have been running optimax.
The tops of the bores have been shamfered. Incorrect spelling i know.
#14
_dave720gtr_
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Posted 21 May 2007 - 10:31 AM
Who did the ring gaping? you or the engine builder ? you say you checked them
or gaped them at 0.22" then there is no way that would of happened anless you missed one ?
most of the 308 me a mate build we gap them at 0.16" we only go up around 0.22" or biger if there going to run NOZ. we have never had a prob with broken ring lands in 308s using acl race flat tops. thay look like hypertec what the part number
pic shows just how big 0.16" is ..
or gaped them at 0.22" then there is no way that would of happened anless you missed one ?
most of the 308 me a mate build we gap them at 0.16" we only go up around 0.22" or biger if there going to run NOZ. we have never had a prob with broken ring lands in 308s using acl race flat tops. thay look like hypertec what the part number
pic shows just how big 0.16" is ..
#15
_v8slrtorana_
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Posted 21 May 2007 - 06:03 PM
How you got the ring in the bore now is how i measured the ring gap.
I got 22th on the top and bottom ring.
The ring set i measured is the off the damaged piston, from that particular bore.
The engine builder did the ring gapping, im just ckecking over measurements to see WTF went wrong.
I got 22th on the top and bottom ring.
The ring set i measured is the off the damaged piston, from that particular bore.
The engine builder did the ring gapping, im just ckecking over measurements to see WTF went wrong.
#16
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Posted 22 May 2007 - 10:21 AM
OK so the rings that were fitted to the damaged piston are still in one piece ?
Take a look at the butting faces of those rings (in particular the second ring) and check for shiny spots indicating they have expanded and touched. Better still see if you can post a pic.
Take a look at the butting faces of those rings (in particular the second ring) and check for shiny spots indicating they have expanded and touched. Better still see if you can post a pic.
#17
_v8slrtorana_
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Posted 22 May 2007 - 05:27 PM
Rings from the damaged piston seem to be in good condition.
If you save the image and zoom in, you can clearly see the butting faces.
Looks like top ring may have butted, not the 2nd.
If you save the image and zoom in, you can clearly see the butting faces.
Looks like top ring may have butted, not the 2nd.
#18
_v8slrtorana_
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Posted 22 May 2007 - 09:39 PM
New infomation.
Piston sits 0.008 above deck.
Bore is 4.060
stroke is 3.48
head is 51cc
compressed head gasket is 0.041
piston dish is 12cc
= Now i know why it f$^ked up = 11.5:1
engine builder told me he built it for 9.5:1 without telling him my head cc, when i gave head cc figures he said is was 10.08:1.
Well, he must have been guessing deck height and piston cc.
Piston sits 0.008 above deck.
Bore is 4.060
stroke is 3.48
head is 51cc
compressed head gasket is 0.041
piston dish is 12cc
= Now i know why it f$^ked up = 11.5:1
engine builder told me he built it for 9.5:1 without telling him my head cc, when i gave head cc figures he said is was 10.08:1.
Well, he must have been guessing deck height and piston cc.
#19
_82911_
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Posted 22 May 2007 - 09:47 PM
check the volume of your chambers again 51cc sounds too small to me.
Unless someone has decked them .100"
Cheers Greg..
Unless someone has decked them .100"
Cheers Greg..
#20
_dave720gtr_
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Posted 22 May 2007 - 09:51 PM
3.48 stroke 0.60" over your swept volume as increase greatly ! it pays to do your maths lucky pistions are cheap
#21
_v8slrtorana_
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Posted 22 May 2007 - 09:58 PM
Me do my maths, nah, this is why i paid this clown to build it.
Now, im doing measurements trying to figure out y it broke.
The only thing i took to this person was my block, crank, rods and cam, the rest he supplied.
Not happy.
Yep, the head CC is extreamly small, i know, there is not alot of meat left on them. They are ready for the bin soon.
Now, im doing measurements trying to figure out y it broke.
The only thing i took to this person was my block, crank, rods and cam, the rest he supplied.
Not happy.
Yep, the head CC is extreamly small, i know, there is not alot of meat left on them. They are ready for the bin soon.
#22
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Posted 23 May 2007 - 12:40 AM
Detonation would also account (to a degree) to the bearing condition... Did the shells still have any crush? Or did they come out easily?
#23
_dave720gtr_
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Posted 23 May 2007 - 01:33 PM
Alot of the time we find the heads are not machined even . one set we cc after thay came back from the machinest .we found one bank at 56cc the other at 63cc
most mecanic/engine builders would never check the cc anless your paying for blue printing
at your best thay might do a ruff gess at the comp
i know its a pissoff" but you could of done a lot more damage
cheers mate!
most mecanic/engine builders would never check the cc anless your paying for blue printing
at your best thay might do a ruff gess at the comp
i know its a pissoff" but you could of done a lot more damage
cheers mate!
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