Did I get doop’d? Probably. You decide.
Nov 20, 2018 | 09:01 PM
#1
Did I get doop’d? Probably. You decide.
In the summer of 2015 I purchased a used 194k mile 2007 NNBS silverado 1500 ccsb with a 5.3 flex fuel truck..the rest of the details are irrelevant.
Fast forward to 6 months ago: I did a afm delete, cam swap, all the valve train, basically the entire top end..etc etc.
Discovery..
Found out it had 243 heads, awesome. Looked like someone had swapped these on more recent based on the gaskets. Didn’t think much past that.
The shortblock took a crap at 265k, bought a Thompson MS 370 short block. Super happy about that.
Then I had a daughter in June, and 3 weeks later in July a full spinal fusion back surgery. Set back after set back then finally this week my buddy pulled the old short block.
Now the “wtf” moment..
The stamped as a gen5 4.8/5.3 and it’s an iron block. BUT it has flat top pistons. My vin states it was definitely a 5.3 when it rolled off the assembly line.
but it’s an iron block with flat tops.
So my conclusion:
someone swapped in a 4.8 at some point
or
someone did a rebuild and added flat top pistons on the 5.3
Is there anyway to tell what the heck I have? I mean it ran **** and I would have 100% believe it was a 5.3
Just lookin for answers/opinions/funny comments
Have at it fellas!
Fast forward to 6 months ago: I did a afm delete, cam swap, all the valve train, basically the entire top end..etc etc.
Discovery..
Found out it had 243 heads, awesome. Looked like someone had swapped these on more recent based on the gaskets. Didn’t think much past that.
The shortblock took a crap at 265k, bought a Thompson MS 370 short block. Super happy about that.
Then I had a daughter in June, and 3 weeks later in July a full spinal fusion back surgery. Set back after set back then finally this week my buddy pulled the old short block.
Now the “wtf” moment..
The stamped as a gen5 4.8/5.3 and it’s an iron block. BUT it has flat top pistons. My vin states it was definitely a 5.3 when it rolled off the assembly line.
but it’s an iron block with flat tops.
So my conclusion:
someone swapped in a 4.8 at some point
or
someone did a rebuild and added flat top pistons on the 5.3
Is there anyway to tell what the heck I have? I mean it ran **** and I would have 100% believe it was a 5.3
Just lookin for answers/opinions/funny comments
Have at it fellas!
Nov 20, 2018 | 09:24 PM
#2
TECH Apprentice
Joined: Aug 2017
Posts: 393
Likes: 64
From: Treasure Coast of Florida
Your engine is an LMG. From 2007-2009 the LMG, LC9 and LY5 all had flat top pistons as they did not have VVT. VVT was introduced in 2010 so those motors got the different pistons along with a slight reduction in compression ratio. The stock camshaft is a single pattern 193-193 .482-.482 116. VVT motors also have a different camshaft grind. All of these motors came with 243 heads too. The LC9 has an aluminum block, the LY5 is not Flex Fuel and was discontinued for 2010.
Nov 20, 2018 | 09:32 PM
#3
TECH Apprentice
Joined: Aug 2017
Posts: 393
Likes: 64
From: Treasure Coast of Florida
Oh, the telltale sign of whether or not your engine is a 4.8 or still original is the crankshaft. The stroke on the 4.8 is 3.27" versus 3.622" for the others. Cams would be different too.
Nov 21, 2018 | 12:23 PM
#6
Excellent reply above!!!
If you pull the pan and the windage tray, You can see the casting number on the crank and that will confirm if its a 5.3L or 4.8L.
From what I have seen, they should be the same as the earlier cranks but with a 58X wheel. I know at some point the casting number changed but not sure if that was for the new DI motors or if it started earlier.
12553482 = 4.8L
12552216= 5.3L
If you pull the pan and the windage tray, You can see the casting number on the crank and that will confirm if its a 5.3L or 4.8L.
From what I have seen, they should be the same as the earlier cranks but with a 58X wheel. I know at some point the casting number changed but not sure if that was for the new DI motors or if it started earlier.
12553482 = 4.8L
12552216= 5.3L
Nov 21, 2018 | 03:52 PM
#7
Gen iv 5.3s are all flat top pistons and 243/799 casting heads. The only real change was in 2010 when they added valve reliefs in the pistons for the addition of VVT.
The gen iv's have nothing to do with the gen 3's.
The gen iv's have nothing to do with the gen 3's.
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