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Old 12-30-2004, 09:55 PM   #11
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Quote:
Originally Posted by kidturbo
So consensus is there is no difference in the long block portion of the 3800 SC or not? Just want to make sure before I put down the cash for a replacement.
I believe the rods and pistons are different. The heads are also different due to the SC'ed having the injectors in the heads vs the non-SC'ed having them in the lower intake manifold.
The lower ends will interchange, but the non-SC lower end will not last nearly as long under boost applications (at least not with higher boost of 8-9+).
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Old 12-30-2004, 10:01 PM   #12
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If your looking for an engine try Ed Morad at http://www.moradpartscompany.com
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Old 12-30-2004, 10:17 PM   #13
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Quote:
Originally Posted by OLBlueEyesBonne
Quote:
Originally Posted by kidturbo
So consensus is there is no difference in the long block portion of the 3800 SC or not? Just want to make sure before I put down the cash for a replacement.
I believe the rods and pistons are different. The heads are also different due to the SC'ed having the injectors in the heads vs the non-SC'ed having them in the lower intake manifold.
Ok thanks, I figued the bottom end was different do to the boost. I'll look for the SC models only then. I'll let you know what I find when I get home and pull the heads, from the sound I bet it'* a valve stuck in the top of a piston.

Cheers.
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Old 01-09-2005, 09:23 PM   #14
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Update: I only spent a couple hours doing diag on this while home last week but here is what I found. Started it up and the knock was still there, cylinder 3 was not firing at all. Checked valve train, pushrods springs looked fine, sounded like a rod so we dropped the pan and checked all of them, no problems. Cylinder 3 sparkplug gap was closed off, the GM dealer had just changed them 20 miles earlier. Brought that piston to the top and took a look inside with a mirror. Many ding marks on the top of the piston, that was enough for me to call it quits for the week until I get time to tear it down.

Has any of you leaned out enough to burn a piston??

Still looking for the root cause of the over boost but I can only conclude that the cat failed and is restricting the exhaust to the point that the SC overfilled the engine and caused it to go lean burning a piston. Unless anyone has a better conclusion, I won't be 100 % until I pull the heads next week now.

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Old 01-09-2005, 11:44 PM   #15
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Chipping a piston (most lovingly refer to it as "chunking") happens fairly frequently in the GP community. The piston goes lean, detonation chips a piece off and the piece flys into the cylinder usually hitting the spark plug leaving a telltale sign (gap closed, broken, etc..). Most of the time this happens when people mod incorrectly by not using supporting mods, or running the motor with large amounts of KR.

If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
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Old 01-09-2005, 11:59 PM   #16
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Quote:
Originally Posted by Rogue
Chipping a piston (most lovingly refer to it as "chunking") happens fairly frequently in the GP community. The piston goes lean, detonation chips a piece off and the piece flys into the cylinder usually hitting the spark plug leaving a telltale sign (gap closed, broken, etc..). Most of the time this happens when people mod incorrectly by not using supporting mods, or running the motor with large amounts of KR.

If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
Ok this sounds a lil familiar......About this time last winter, when my friend had my car, before he gave it to me......The number 4 cylinder randomly started thumping and hitting really hard and we pulled the plug out and the electrode and the center of the spark plug was gone.....No one knew where it went......Or how it happend...but we put a new one in and it hasn't done it again????Maybe close to wahat happening with yours?
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Old 01-10-2005, 12:11 AM   #17
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Quote:
Originally Posted by LakevilleSSEi
Quote:
Originally Posted by Rogue
Chipping a piston (most lovingly refer to it as "chunking") happens fairly frequently in the GP community. The piston goes lean, detonation chips a piece off and the piece flys into the cylinder usually hitting the spark plug leaving a telltale sign (gap closed, broken, etc..). Most of the time this happens when people mod incorrectly by not using supporting mods, or running the motor with large amounts of KR.

If the cylinder wall is not scratched you can get away with replacing the piston, if it is, your looking for a new bottom end.
Ok this sounds a lil familiar......About this time last winter, when my friend had my car, before he gave it to me......The number 4 cylinder randomly started thumping and hitting really hard and we pulled the plug out and the electrode and the center of the spark plug was gone.....No one knew where it went......Or how it happend...but we put a new one in and it hasn't done it again????Maybe close to wahat happening with yours?
The cylinder piece and the spark plugs electrode (if broke) usually passes through the engine so its not uncommon to not see it (unless its a fairly large piece). It is also very possible to run the motor with a chipped piston as long as there isnt total compression loss (although your compression on that cylinder will be lower). It is not wise to run a motor hard with a chipped piston as it more suceptable to damage from knock. You can "scope" your cylinder usually with a rental boroscope form say Autozone and look for chips in the cylinder head.

I've known a few people who just changed the plug and went on with things but continued to be hard on it and eventually the piston failed entirely.
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Old 01-10-2005, 12:25 AM   #18
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Thanks guys, I feel better already

I actually called the GM dealer and gave the service mgr heck for letting an amateur work on it. Said he must have dropped the plug and never gaped it again, then after we pulled the pan to check the rods and could find nothing wrong I started thinking Maybe I should go back up top and take another look at that plug, closer inspection showed some small specks of aluminum welded to the back side of the electrode. That made me feel bad and had to call him up and beg for forgiveness.. But they were driving it when it chunked the piston so I think we're even.

The only good things are the cylnder wall looks ok from the bottom side, and the pan is still off so getting the piston out should take less work from here.
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Old 01-10-2005, 12:35 AM   #19
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Quote:
Originally Posted by kidturbo

The only good things are the cylnder wall looks ok from the bottom side, and the pan is still off so getting the piston out should take less work from here.
Um, don't the piston'* come out the topside? That'* how I had to do it on my old Shelby Dodge'* and Chrysler Turbo'*, and how I've been told it'* been done this way with almost every engine they can think of.
But that'* not to say I'm right -I've been wrong before.
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Old 01-10-2005, 12:40 AM   #20
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Quote:
Originally Posted by OLBlueEyesBonne
Quote:
Originally Posted by kidturbo

The only good things are the cylnder wall looks ok from the bottom side, and the pan is still off so getting the piston out should take less work from here.
Um, don't the piston'* come out the topside? That'* how I had to do it on my old Shelby Dodge'* and Chrysler Turbo'*, and how I've been told it'* been done this way with almost every engine they can think of.
But that'* not to say I'm right -I've been wrong before.
Easy to take the head off to pull it out the top, but you still have to connect and disconnect the rod from the crankshaft, which is why I think he said it would be easier if the pan is still off.
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