5.3L Ls NA Short Block
Reid’s Speed Shop’s 5.3L LS NA Short Block
A Proven LS Foundation, Rebuilt for Performance.
The Reid's Speed Shop 5.3L N/A Performance Short Block takes one of the most proven and versatile foundations in the LS family and transforms it into a completely machined, purpose-built foundation for your naturally aspirated performance combination.
Beginning with a seasoned GM LM7 iron block, each short block undergoes professional machine work and is bored .020" over to 3.800", bringing displacement to approximately 329 cubic inches. Rather than relying on an unknown high-mileage takeout engine, the foundation is thoroughly prepared and precision assembled with components selected specifically for dependable naturally aspirated street performance.
Inside, the proven GM crankshaft and powdered-metal forged connecting rods are paired with new forged flat-top pistons featuring dual valve reliefs and coated skirts, along with premium MAHLE plasma-moly piston rings and performance bearings. The flat-top piston design provides excellent flexibility when selecting your cylinder heads, producing approximately 10.5:1 compression with 61cc chambers, 9.9:1 with 64cc chambers, and 9.5:1 with 68cc chambers. This allows the finished combination to be tailored around your desired performance level, cylinder head selection, and intended street use while retaining the durability that has made the iron-block 5.3L such a proven LS foundation.
Every short block is professionally machined, precision assembled, and clearances are verified throughout. Whether you're building a responsive street cruiser, classic LS swap, weekend hot rod, or a higher-revving naturally aspirated combination, this package gives you a properly prepared foundation while leaving cylinder head, camshaft, induction, and accessory selection in your hands.
START WITH A PROVEN IRON LS FOUNDATION. FINISH IT YOUR WAY.
Starting out at $3,200
Typical investment varies based on component options, and customer-selected upgrades.CHOOSE YOUR 5.3L SHORT BLOCK PACKAGE
Short Block — Starting at $3,200
A professionally machined and precision-assembled 5.3L foundation for the enthusiast who wants complete control over the remainder of their combination.
Includes the fully machined GM iron block, GM crankshaft, OEM powdered-metal forged connecting rods, forged flat-top pistons, MAHLE plasma-moly piston rings, performance bearings, and complete rotating assembly.
Cam Kit Short Block — Starting at $4,200
Take the same professionally machined and assembled forged-piston foundation and add a performance valvetrain package selected around your vehicle, intended use, and performance goals.
Includes everything from the Short Block Package, plus your performance hydraulic roller camshaft and matched supporting valvetrain and timing components.
Sealed-Up Short Block — Starting at $4,800
Our most complete 5.3L short block package, designed for the enthusiast who wants the majority of the bottom-end assembly and supporting systems completed before taking delivery.
Includes everything from the Cam Kit Short Block Package, along with the remaining oiling, timing, sealing, and supporting components required to deliver a professionally assembled and sealed performance foundation ready for your cylinder head and induction combination.
Quick Look
Engine Block
Seasoned GM LM7 5.3L Iron Engine Block
Professionally Cleaned, Inspected & Machined
Bored .020" Over to 3.800"
Approximately 329 Cubic Inches
Deck Surfaces Professionally Machined
Cylinder Bores Finish-Honed for Performance Ring Package
OE Hydraulic Roller Camshaft Design
6-Bolt Cross-Bolted Main Cap Design
All Critical Block Dimensions Verified
Rotating Assembly
GM 3.622" Stroke Crankshaft
OEM GM Powdered-Metal Forged Connecting Rods
Forged Flat-Top Performance Pistons
Dual Valve Reliefs
Coated Piston Skirts
MAHLE Plasma-Moly Performance Piston Rings
Performance Rod & Main Bearings
New Camshaft Bearings
Precision Assembly
Professionally Machined
Precision Blueprint-Assembled
Bearing Clearances Verified
Piston-to-Wall Clearance Verified
Piston Ring End Gaps Verified
Crankshaft Endplay Verified
Connecting Rod Side Clearance Verified
Rotating Assembly Checked Throughout Final Assembly
Ready for Your Cylinder Head, Camshaft & Induction Combination
Compression
Approximately 10.5:1 Compression with 61cc Cylinder Heads
Approximately 9.9:1 Compression with 64cc Cylinder Heads
Approximately 9.5:1 Compression with 68cc Cylinder Heads
Available Configurations
Assembled Short Block — Starting at $3,000
Cam Kit Short Block — Starting at $4,200
Sealed-Up Short Block — Starting at $4,800
Why Choose a Reid’s speed Shop Crate engine:
When purchasing a crate engine, you have many options available—from large production companies to smaller independent builders. At Reid’s Speed Shop, the difference is simple: this isn’t mass production—it’s personal craftsmanship.
Every engine is carefully assembled with attention to detail and built using combinations that have been thoughtfully researched and proven to work together. Rather than being one of hundreds of engines moving down an assembly line, your engine receives the kind of focus and care that only a small, dedicated shop can provide.
Communication is also a major part of the experience. Throughout the process, customers are kept informed and updated as their engine comes together. Photos and updates are often shared so you can actually see the progress of your engine being built rather than simply receiving a shipment notice when it’s finished.
Whenever possible, customers are also given the opportunity to hear their engine run before delivery. Whether in person or through a video demonstration, this allows you to see and hear the engine come to life—giving you confidence in how it runs, idles, and performs before it ever leaves the shop.
At Reid’s Speed Shop, the goal isn’t to move engines as quickly as possible—it’s to build them correctly and ensure every customer feels confident in the investment they’ve made. Building engines is more than just a job here; it’s a genuine passion and a craft that is taken seriously.
When you choose Reid’s Speed Shop, you’re not just purchasing an engine—you’re working directly with the person building it, ensuring transparency, accountability, and a level of care that large-scale production simply cannot offer.