PONTIAC 12561166 Block 5.7L V8

( Manufacturer Part Number: 12561166 ), ( Part Type: Block ), ( Engine Size: 5700 ), ( Performance Part: No ), ( Tag : 582644 ), ( Item Warranty: 30 Days )

Review PONTIAC 5.7l V8 Bare Short Block fits LS1 GTO 2004

The Pontiac GTO 2004 5.7L V8 LS1 Bare Block is a powerful and iconic engine that was originally installed in the legendary Pontiac GTO muscle car. This is a factory-built, cast iron block engine that carries the part number 12561166.

The LS1 engine is known for its robust and high-performance design. It features a compact, cross-bolted main bearing structure that provides increased strength and durability. The block has a bore size of 4.000 inches and a stroke length of 3.622 inches, which results in a total displacement of 346 cubic inches.

The cylinder bores are lined with forged pistons that are designed to handle the high compression ratios and power output of the engine. The pistons have a reciprocating weight of 233 grams and a compressive height of 8.62 inches.

The block also features a deep-sump oil pan that provides adequate oil capacity and pressure at all RPM levels. It has seven main bearings and five counterweights that help to reduce vibration and provide a smoother running engine.

The LS1 block is equipped with a cast iron crankshaft that features a forged steel connecting rod assembly. The crankshaft has a counterweighted design that helps to balance the engine and reduce vibration. It also features a forged steel camshaft that is capable of producing high valve lift and duration for optimal performance.

The block is also designed to accommodate various fuel systems, including EFI and carbureted setups. It comes with a factory-installed balance shaft system that helps to reduce vibration and improve the overall smoothness of the engine.

The 2004 Pontiac GTO 5.7L V8 LS1 Bare Block is a high-performance engine that delivers impressive power and torque. It is a must-have for enthusiasts and performance builders who are looking to build a high-performance muscle car or hot rod. With its robust design, high-performance capabilities, and legendary status, this engine is sure to exceed your expectations.

Buying a 2004 Pontiac GTO 5.7L V8 LS1 bare block can be an exciting prospect for automotive enthusiasts seeking to build a high-performance engine. Here are some potential pros and cons to consider before making a purchase:

1. Performance: A bare block offers the opportunity to customize every aspect of the engine, allowing for maximum performance potential.

2. Cost-effectiveness: Purchasing a bare block can be more cost-effective than buying a complete engine or a pre-built aftermarket engine.

3. Learning Experience: Building an engine from a bare block can be a rewarding and educational experience for those looking to expand their mechanical skills.

4. Availability: GTO LS1 blocks are relatively common and easily available on the aftermarket, making them a popular choice for engine swaps and builds.

1. Time-consuming: Building an engine from a bare block requires a significant investment of time and effort.

2. Skill level: Building an engine from a bare block requires a high level of mechanical expertise and experience.

3. Tools and resources: Building an engine from a bare block requires access to specialized tools and resources, which can add to the overall cost.

4. Risk of damage: Handling a bare engine block can be risky, as there is no cooling system or other protective measures in place, increasing the risk of damage during transportation or installation.

In conclusion, purchasing a 2004 Pontiac GTO 5.7L V8 LS1 bare block can be an excellent choice for those seeking maximum performance potential, a cost-effective option, and a learning experience. However, it requires a significant investment of time, expertise, and resources, and carries the risk of potential damage.

If you have the mechanical skills, experience, time, and resources to build an engine from a bare block, then purchasing a 2004 Pontiac GTO 5.7L V8 LS1 bare block can be an excellent choice. However, if you lack the time, expertise, or resources, or prefer a more turnkey solution, consider purchasing a complete engine or a pre-built aftermarket engine instead.

Details:

It also arrived right around the time it said would. Every order is meticulously packaged with extra protection and padding. Quality Assurance. Parts are extremely well priced as with super fast shipping.

The value was excellent. They take pride in their work. If I could leave a better that 5 star review would. Make Pontiac.

I will definitely come back to his page when i'm looking for something in the future. The also did an excellent job packaging a very oddly shaped part roll bar. Not only where they flexible on their price, communication, /pics were perfect. 100% will purchase from again.

Items are EXACTLY as you see them in the photo, no BS. All used items will show normal signs of use such as nicks, scuffs, and scratches. All parts are tested and inspected for reliability performance. Shipping time was excellent.

This item is used but in good working condition. The packaging was by far the best i've ever seen for a heavy part. Component was exactly as described and in the photos on listing. Will definitely do business again.

The engine wiring harness was just as pictured there only one damaged wire connector I had to re splice, disappointing but not a big deal. And I m glad they respectfully accepted my offer which made the value of product worth buying. I'm happy with the value compared to new. Fast Reliable.

An overall great buying experience and an excellent value. Part Number 12561166, Body Type Coupe, Engine LS1, Condition None, Odometer 169980, Exterior Color Impulse Blue Metallic, Paint Code 24, Interior Blue, Trim 746. Packaging would have been sufficient to ship a Faberge egg. These folks at J auto are top notch and deserve a full review.

I'm looking forward to doing business with them again.: 5.7l v8 LS1 short block, no heads or oil pan. Contact for fitment Purchase Price. I was very satisfied with it.

Turns over smooth.

part #: 12561166 prices

• $4500.00-$4950.00

specifications grokengines:

• for models: Ls1, Gto
• for makes: Pontiac
• for years: 2004
• mpn: 12561166
• part type: Block
• engine size: 5700
• performance part: No
• tag : 582644
• item warranty: 30 Days

offer grokengines:

• started: February 26, 2026
• options: Ship-to-home
• best offers: True
• sold: 0
• availability: In Stock
• quantity: 1

shipping grokengines:

• service: Flat Rate Freight
• cost: $295.00
• class: Freight
• type: Fixed

seller grokengines:

• city: Marshallville, Ohio
• # reviews: 37338
• rating: 100.0%

payments grokengines:

• other
• wallet: Paypal
• credit card: Mastercard

general grokengines:

• condition: Used
• Car Truck Parts Accessories > Engines Engine Parts > Engines

returns grokengines:

• policy: Returns Accepted
• time: 60 Days
• paid by: Buyer

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