The Mopar 318 has a reputation among enthusiasts as a durable workhorse, but “indestructible” is a nickname, not a proven reliability finding. First identify which 318 you mean: Chrysler made an earlier A-series engine with polyspherical heads and a later LA-series small-block, and their specifications and rebuild guidance should not be assumed to match.
This overview focuses on the LA 318, explains the distinction, and points readers toward references for researching or rebuilding the correct engine.
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Two different engines called the 318
The 318 name can refer to Chrysler’s A-series Poly V8 or the later LA-series small-block V8. The Poly uses polyspherical cylinder heads; the LA belongs to Chrysler’s LA small-block family. They are distinct engine families, so a specification or parts recommendation for one should not be applied to the other without checking.
| What to identify | A-series 318 | LA-series 318 |
|---|---|---|
| Engine family | A-series, commonly called Poly | LA-series small-block |
| Head design | Polyspherical heads | LA-series design |
| Before using a manual or ordering parts | Confirm the engine and application | Confirm the engine and application |
Check the engine family and the vehicle’s year and application before relying on specifications, buying parts, or following rebuild instructions. The research available for this article does not verify detailed interchange rules or exact engine specifications.
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- Dual-plane, low-rise intake manifolds with a 180 degree firing order.Material:Aluminum
- Boosts torque from off-idle to 5, 500 RPM
- Available with non-EGR style
- Delivers improved throttle response over stock intakes
- Comes with a natural finish
When did the LA 318 come out?
The LA 318 is described as entering volume production for the 1968 model year. Some summaries use 1967 for its introduction period, so distinguish the model year from the calendar year rather than treating the dates as interchangeable.
Is the Mopar 318 really indestructible?
“Indestructible” reflects enthusiast lore, not a demonstrated engineering property. The available research does not establish comparative failure rates, expected service life, or a unique reliability advantage over other engines.
Rank #2
- Dual-plane, low-rise intake manifolds with a 180 degree firing order
- Boosts torque from off-idle to 5, 500 RPM
- Available both in EGR and non-EGR styles
- Delivers improved throttle response over stock intakes
- Comes with a natural finish
As with any used engine, condition, maintenance, its past application, and previous repairs or machine work matter. A reputation is not a substitute for inspection or for identifying the exact engine before choosing service information.
Can you rebuild a Mopar 318?
Dedicated rebuild references are available for LA-series engines. CarTech describes Mopar Small-Block LA-Series Engines 1964–1992: How to Rebuild as a guide to pre-Magnum LA engines, covering major systems and step-by-step rebuild work. Confirm that your engine is an LA 318 before using it; the guide’s LA-series scope does not make it a manual for the older A-series Poly engine.
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Rank #3
- Provides outstanding throttle response and increased torque
- Delivers outstanding performance for the street with complete emissions compatibility
- Basic operating RPM is from ideal to 5, 500 RPM
- Plenum and base material is made of aluminum with a natural finish
- Performer intake is 50-state street legal, when used with the correct carburetor and in the correct application
For a rebuild, use a reference that matches the engine family and application. Mopar’s catalog also lists small-block building and modification references, while Mopar Tech Authority describes access to service bulletins, wiring schematics, parts identification, and vehicle documents. These resources do not, by themselves, confirm fitment for a specific 318.
How to find the right 318 reference
- Identify whether the engine is an A-series Poly or an LA-series small-block.
- Record the vehicle year and application so you can check whether a manual or parts listing is relevant.
- Choose a reference whose stated engine-family coverage matches your engine and whose scope fits your goal, such as stock rebuilding or modification.
- Verify part fitment and service information for the specific engine and vehicle before ordering or beginning work.
Mopar’s repair-parts information describes offerings that include engines and engine parts, but it does not establish a particular 318 part’s current availability or fitment. Verify the details for your vehicle and engine family.
Rank #4
- 1500-6500 RPM Range
- Dual Plane Type-4150 Style Flange
- 4. 2 in. Front Height, 4. 72 in. Center Height, 5. 25 in. Rear Height
- Satin Finish
- Non-EGR
FAQ
What is the difference between a 318 Poly and an LA 318?
They are different Chrysler engine families. The A-series 318 is commonly called the Poly and has polyspherical heads; the LA 318 is a later LA-series small-block. Do not assume their specifications, parts, or rebuild instructions are interchangeable.
When did the LA 318 come out?
One history reference places its volume-production start at the 1968 model year. Some summaries call 1967 its introduction period, so check whether a source means model year or calendar year.
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- Dual-plane, low-rise intake manifolds with a 180 degree firing order
- Boosts torque from off-idle to 5, 500 RPM
- Available with non-EGR style
- Will not accept stock Motor craft spread-bore carburetor
- Comes with a natural finish
Which manual covers the LA 318?
CarTech’s Mopar Small-Block LA-Series Engines 1964–1992: How to Rebuild covers pre-Magnum LA-series engines. Confirm your engine is an LA 318, not the earlier A-series Poly, and check the guide’s stated scope against your application.
Is a 318 always reliable because it is called indestructible?
No. “Indestructible” is a reputation, not a guarantee or a measured reliability claim. The condition and history of an individual engine matter.
