LS1 rods and piston differential
Thread Starter
Teching In
Joined: Jan 2012
Posts: 10
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LS1 rods and piston differential I just repair my 98 trans am. 1st cylinders rod bearing is clearance and engine knocking. It s open bearing is broken only first cylinder. I bought car and give with new piston/rods bearing and shaft too. But piston/rods are little different. Which is better? Clean parts are new and oiling parts are too good condition. Sorry no picture... How I can add picture?
Last edited by lofjussi; May 15, 2013 at 02:50 PM.
Can a sponsor or other hands on experienced user confirm this?
On The Tree
Joined: Jul 2010
Posts: 158
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Copied from Engine Builder...
http://www.enginebuildermag.com/Arti...all_block.aspx
1997 -'04 - 5.7L Cars
All of the 5.7L blocks are aluminum castings and they're all very similar, but there are a couple of subtle differences between the early ones and the late ones.
The 1997-'98 blocks with the 12550592 casting had two holes for the oil galleys that were flush with the back of the block itself, so the right lifter galley was fed by a shallow crossover in the back cover. These blocks also had a 24.5 mm hole drilled straight through the main webs to allow better "bay-to-bay breathing."
GM discovered during dyno testing that there was too much pressure in the crankcase due to the amount of air and oil vapor that was trapped between the main caps, so they drilled a hole through all five bulkheads to allow the engine to "breathe" from one bay to another. That eliminated the pressure build-up that was causing some internal problems.
GM used several castings for the LS1 motors from '99-'04, but they're all pretty much the same so it doesn't really make a lot of difference which one you use. However, there are a couple of changes that make each of them slightly different.
The right front corner of the block was reinforced in '99 and there was a deep oil slot added to the back of the block to allow more oil to flow to the right hand lifter galley. Look for a 12559378 or a 12560626 casting.
The 1256118 casting was originally designed for the high performance LS6 that was introduced in '01, but it showed up in some LS1 applications in '01 and '02 and it was used for all the Corvette motors in '03 and '04. The only difference between it and the previous block was the addition of two cast slots in each of the three center mains. They replaced the holes that were drilled through the bulkheads on all the other '97-'01 blocks.
http://www.enginebuildermag.com/Arti...all_block.aspx
1997 -'04 - 5.7L Cars
All of the 5.7L blocks are aluminum castings and they're all very similar, but there are a couple of subtle differences between the early ones and the late ones.
The 1997-'98 blocks with the 12550592 casting had two holes for the oil galleys that were flush with the back of the block itself, so the right lifter galley was fed by a shallow crossover in the back cover. These blocks also had a 24.5 mm hole drilled straight through the main webs to allow better "bay-to-bay breathing."
GM discovered during dyno testing that there was too much pressure in the crankcase due to the amount of air and oil vapor that was trapped between the main caps, so they drilled a hole through all five bulkheads to allow the engine to "breathe" from one bay to another. That eliminated the pressure build-up that was causing some internal problems.
GM used several castings for the LS1 motors from '99-'04, but they're all pretty much the same so it doesn't really make a lot of difference which one you use. However, there are a couple of changes that make each of them slightly different.
The right front corner of the block was reinforced in '99 and there was a deep oil slot added to the back of the block to allow more oil to flow to the right hand lifter galley. Look for a 12559378 or a 12560626 casting.
The 1256118 casting was originally designed for the high performance LS6 that was introduced in '01, but it showed up in some LS1 applications in '01 and '02 and it was used for all the Corvette motors in '03 and '04. The only difference between it and the previous block was the addition of two cast slots in each of the three center mains. They replaced the holes that were drilled through the bulkheads on all the other '97-'01 blocks.
Thread Starter
Teching In
Joined: Jan 2012
Posts: 10
Likes: 0
Hello
I am from Finland and english is it not so clear...
What modification I have to do my block(12559378)? I understand that this is better block and without modifications or am I right?
And piston/rods, which is better (picture original message) left or right?
Thanks for help!
Br. Jussi
I am from Finland and english is it not so clear...
What modification I have to do my block(12559378)? I understand that this is better block and without modifications or am I right?
And piston/rods, which is better (picture original message) left or right?
Thanks for help!
Br. Jussi
Last edited by lofjussi; May 16, 2013 at 08:43 AM.
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