need help with block casting numbers
01-17-2004, 04:20 PM
#1
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Join Date: Feb 2003
Location: Silicon Valley, CA
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need help with block casting numbers
Came around a very good deal for a B body LT1 engine- $500 with harness from a neighbor, says just 60k miles, gives a promisiry note that it will run for 3 months!! The only thing is that I don't know if it's a 4.3 or 5.7 ?? The block casting number at the back of the block was 5716 SGT , he said it was from a police impala, and I did a 5 hour search for it and couldn't find anything. Guy needs money that's why he is selling. A spare good motor is always good, especially when two people in my family own an LT1 car. Can anybody help me or give some website I could look in.
Thanks
Tomas
Thanks
Tomas
01-17-2004, 05:19 PM
#2
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From the "Rebuilding the LT1" article:
BLOCKS
350 - There are two blocks, one with two-bolt mains and one with four-bolt mains. They both have the same 10125327 casting number, so there’s no sure way to know which one you have until you get the pan off. However, if it came out of a Corvette, it should be a four-bolt block, and if it came out of anything else, it was supposed to be a two-bolt. GM used the two-bolt block for everything but the Corvette because it had plenty of strength and it weighed a little bit less.
265 - There was only one block used for the 265 cid version of the LT1. It’s a 10168588 casting that had the numbers "4.3" cast on the side, too. It’s real easy to spot if the heads are off because of the small 3.74" bore.
350 - There are two blocks, one with two-bolt mains and one with four-bolt mains. They both have the same 10125327 casting number, so there’s no sure way to know which one you have until you get the pan off. However, if it came out of a Corvette, it should be a four-bolt block, and if it came out of anything else, it was supposed to be a two-bolt. GM used the two-bolt block for everything but the Corvette because it had plenty of strength and it weighed a little bit less.
265 - There was only one block used for the 265 cid version of the LT1. It’s a 10168588 casting that had the numbers "4.3" cast on the side, too. It’s real easy to spot if the heads are off because of the small 3.74" bore.
01-18-2004, 12:19 PM
#4
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Posts: 1,462
Re: need help with block casting numbers
Originally posted by tanker
Came around a very good deal for a B body LT1 engine- $500 with harness from a neighbor, says just 60k miles, gives a promisiry note that it will run for 3 months!! The only thing is that I don't know if it's a 4.3 or 5.7 ?? The block casting number at the back of the block was 5716 SGT , he said it was from a police impala, and I did a 5 hour search for it and couldn't find anything.
Came around a very good deal for a B body LT1 engine- $500 with harness from a neighbor, says just 60k miles, gives a promisiry note that it will run for 3 months!! The only thing is that I don't know if it's a 4.3 or 5.7 ?? The block casting number at the back of the block was 5716 SGT , he said it was from a police impala, and I did a 5 hour search for it and couldn't find anything.
Anyway, if you scrape some more of the 'crap' away, a closer observation will reveal the digits to actually be 57(L)(G) SG(L). An even closer look, and this may require a super clean block as well, will reveal 5(.)7LG.....This should identify a 5.7 litre block. Even with a clean block, sometimes difficult to identify the 'dot' from other casting texture, but it's there.
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