C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Difference in B-body LT1 blocks

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Old Sep 20, 2005 | 09:58 AM
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Default Difference in B-body LT1 blocks

I'm looking for a new LT1 due to a spun bearing (see other thread: http://forums.corvetteforum.com/show...56&forum_id=48)

I found a few B-body LT1's locally. A forum member mentioned that there are two versions of that motor, one is not a true 350. Can someone point out the differences so that when I take a look at these motors I can ensure I'm looking at the right one?

Thanks!
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Old Sep 20, 2005 | 10:01 AM
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Originally Posted by ScaryFast
I'm looking for a new LT1 due to a spun bearing (see other thread: http://forums.corvetteforum.com/show...56&forum_id=48)

I found a few B-body LT1's locally. A forum member mentioned that there are two versions of that motor, one is not a true 350. Can someone point out the differences so that when I take a look at these motors I can ensure I'm looking at the right one?

Thanks!
The B-bodies could get a L99 4.3L LT1 style motor as well as the 350. Some prefer the F or B body LT1 as they are 2 bolt and then thry machine the block for 4 bolt splayed caps.
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Old Sep 20, 2005 | 11:46 AM
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The 4.3 L block has a much smaller bore (3.75" vs. 4.00") than the 5.7 L one.
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Old Sep 20, 2005 | 01:12 PM
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Thanks for the info. If the motors are assembled so that I can't measure the bore are there any other signs or markings, numbers, etc on the block I could see?

For a stock HP motor is it necessary to go to the 4 bolt? I'm going to turn my current 4 bolt motor into a stroker, this one's just to get me by.

Thanks again.
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Old Sep 20, 2005 | 01:49 PM
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Originally Posted by ScaryFast
Thanks for the info. If the motors are assembled so that I can't measure the bore are there any other signs or markings, numbers, etc on the block I could see?

For a stock HP motor is it necessary to go to the 4 bolt? I'm going to turn my current 4 bolt motor into a stroker, this one's just to get me by.

Thanks again.
A 4 bolt is not needed for a driver. The 2 bolt caps can actually take quite a bit of power.

Sorry I can't help you out on telling the L99 apart from the others.
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Old Sep 20, 2005 | 02:23 PM
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Casting Numbers on block:

10168588 = 265 ci, 1994-1996, 2 bolt, L99, Gen II, 4.3L, B-Body, Reverse Flow Cooling

10125327 = 350 ci, 1992-1996, 2 bolt (B & F Body) & 4 bolt (Y Body), LT1, Gen II, 5.7L, Reverse Flow Cooling

10125327 = 350 ci, 1996, 4 bolt, LT4, Gen II, 5.7L, Reverse Flow Cooling


The block code, which is stamped on top of the passenger side of the block at the rear, is just behind the intake manifold.

Take Care!
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Old Sep 20, 2005 | 03:57 PM
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Kid -

Thanks a million. I'll check the numbers.
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Old Sep 20, 2005 | 08:52 PM
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http://www.automotiverebuilder.com/ar/ar99928.htm
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Old Sep 21, 2005 | 10:54 AM
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Mojo that's a great link. Thanks.

The motors are the 5.7L block, iron heads. I"m discussing whether or not it's worth swapping my cam into the motor or just dropping it in stock and working mine completely.

280 hp sounds sooo low...
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