differences in the ls3 and ls7 blocks?

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Jan 12, 2011 | 04:32 PM

allblowdup

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differences in the ls3 and ls7 blocks?

I know that the ls7 liners are longer and the extra head bolt but other than that I don't about any differences in the block itself. could I use ls3 parts inside a ls7 block if was so inclined?

Jan 12, 2011 | 04:34 PM

Sales4@Texas-Speed

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LS7 blocks are a 4.125" bore and LS3 blocks are 4.065". There is no way to put LS3 internals inside of an LS7 aluminum block.

Jan 12, 2011 | 04:56 PM

allblowdup

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I should have clarified myself better. I am looking at doing an 4.185 bore x 4.25 stroke in an alum block. I can get an ls3 sleeved or sleeve a ls7 if the rest will work fit.

Jan 12, 2011 | 10:08 PM

Stang's Bane

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Start with the ls3

Jan 12, 2011 | 10:35 PM

Steve - Race Eng

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LS3 or LS7

The LS3 or LS2 block for that matter are better and less expensive choices for sleeving unless you already own an LS7 block. I actually prefer the LS2 because the old sleeves clean out better during machining.

The center main bearing bulkhead is stronger on these two than on the LS7 block. You are giving up the steel main caps but the stock powdered metal caps are more than adequate for most builds.

I have sleeved many blocks, both dry and MID for 454" and larger builds including the 468" block in the Hot Rod Magazine cylinder head test article.

Steve

Quote:

Originally Posted by allblowdup

I should have clarified myself better. I am looking at doing an 4.185 bore x 4.25 stroke in an alum block. I can get an ls3 sleeved or sleeve a ls7 if the rest will work fit.

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Jan 12, 2011 | 10:49 PM

Sales4@Texas-Speed

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Quote:

Originally Posted by allblowdup

I should have clarified myself better. I am looking at doing an 4.185 bore x 4.25 stroke in an alum block. I can get an ls3 sleeved or sleeve a ls7 if the rest will work fit.

Ok, sorry I didn't read the first post right. In this case I would start with an LS3 or LS2 as Steve has said. Those LS7 blocks are pretty expensive to start with.

Jan 17, 2011 | 12:48 AM

BlueFish

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From: SOCAL

Steve has done just that with my blown LS3 block (MID Sleeves) and I now have a 434ci (4.155 bore and 4.00" stroke) with LS7 top end and works great. Make sure to complete the block with Ported heads and as Steve would recommend Evans water pump and NPGr coolant.

Karn