Engine Timing Set Replacement Guide for the 1974-1981 Plymouth Trailduster
Keep your Trailduster's V8 running strong by replacing a worn timing set before it causes major problems.
- Immediately replace any original timing set that has a nylon-toothed camshaft gear with an all-steel set.
- Choose a high-quality aftermarket brand like Melling or Edelbrock for proven reliability and durability.
- Verify if your engine needs a single-bolt or three-bolt cam sprocket before ordering parts.
- While the timing cover is off, it is a good idea to also replace the front crank seal and water pump gaskets.
Is Your Trailduster's Timing Chain on its Last Legs?
If you have a 1974-1981 Plymouth Trailduster, especially one with a 318 or 360 V8 engine, the timing set is a part you shouldn't ignore. Many of these engines originally came with a camshaft sprocket that had nylon-coated teeth. Over decades of use, this nylon becomes brittle, cracks, and can break off. When this happens, the timing chain becomes very loose, which can cause it to jump a tooth on the sprocket. This throws off your engine's timing, leading to a host of problems.
Key Failure Point: Nylon Cam Gears
The original nylon-toothed camshaft gears are a known failure point on older Mopar engines. The nylon flakes off, clogs the oil pickup screen, and creates slack in the timing chain. If you are replacing your timing set, it is essential to choose a new set with all-steel sprockets for long-term reliability.
Symptoms of a Failing Timing Set
A worn timing set will give you some warning signs. Don't ignore them, as a complete failure is much more expensive to fix. Common symptoms include:
- Rattling Noise: A loose timing chain often makes a rattling or clattering sound from the front of the engine, especially when the engine is idling or warming up.
- Engine Misfires and Rough Running: When the chain stretches or jumps a tooth, the cam timing becomes incorrect. This can cause the engine to run rough, misfire, or lose power.
- Loss of Power and Poor Fuel Economy: An engine with incorrect valve timing will not run efficiently. You may notice your truck feels sluggish and uses more gas.
- Metal Shavings in Oil: As the chain and sprockets wear, tiny metal particles can end up in the engine oil. If you see metallic flakes during an oil change, it's a major red flag.
Choosing the Right Aftermarket Timing Set
For a vehicle of this age, high-quality aftermarket parts are often better than searching for rare and expensive New Old Stock (NOS) OEM parts. Aftermarket brands offer durable, all-metal designs that fix the original nylon gear problem. Here’s a breakdown of available brands:
Performance & Heavy-Duty Tier
- Melling / Melling Select Performance: Melling is a highly respected name in engine parts and a top choice for Mopar builders. Their timing sets are known for quality and durability. Many owners trust Melling for a reliable, long-lasting replacement that meets or exceeds original standards.
- Edelbrock: Known for performance, Edelbrock offers high-quality double roller timing chains. These are a great upgrade for durability, especially for modified engines or heavy use like towing and off-roading. They often feature multiple keyways on the crank sprocket to allow for timing adjustments.
Standard Replacement Tier
- Cloyes: Cloyes is a well-known brand that is frequently recommended in forums for being a solid, US-made option. Their standard replacement and double-roller sets are popular choices. However, be aware that some experiences suggest their lower-priced, economy-grade sets may have quality control issues with chain slack out of the box. For reliability, choosing their higher-grade "True Roller" sets is a safer bet.
- INA: INA is a major global manufacturer that often supplies original parts to carmakers. While not as commonly discussed in Mopar forums for this specific vintage, their reputation for quality is generally excellent. An INA set would likely be a reliable, OEM-quality replacement.
Pro Tip: Single-Bolt vs. Three-Bolt Camshaft
When ordering, you must know if your engine's camshaft requires a single-bolt or three-bolt sprocket. Many original cams from this era use a single bolt. If the camshaft has been upgraded, it might use a three-bolt design. It's best to remove the timing cover and check before ordering your new set to avoid mistakes.
Estimated Costs for Timing Set Replacement
| Part or Service | Estimated Cost |
|---|---|
| New Aftermarket Timing Set | $32 - $186 |
| Shop Labor | $450 - $700 |
| Total Estimated Cost | $482 - $886 |
Costs are estimates and can vary based on your location, the specific parts chosen, and your mechanic's labor rate.
Frequently Asked Questions
Should I get a standard "silent" chain or a double roller chain?
For a stock daily driver, a quality all-metal silent chain set from a brand like Melling is perfectly adequate. A double roller chain (offered by brands like Edelbrock and Cloyes) is stronger and stretches less, making it a great upgrade for longevity, performance builds, or heavy-duty use. It may produce a very slight whirring noise at idle.
Do I need a timing chain tensioner?
Most Chrysler LA small block engines from this era did not use a timing chain tensioner from the factory. While some builders add aftermarket tensioners, it is generally not necessary with a quality, tight-fitting timing set.
How do I know if my timing chain has stretched?
A mechanic can check for slack by removing the distributor cap and turning the engine's crankshaft back and forth by hand with a socket on the harmonic balancer bolt. By observing how many degrees the crank turns before the distributor rotor begins to move, they can measure the slack. More than a few degrees of slack indicates a stretched chain.
Is this a good time to replace other parts?
Yes. Since you have to remove the water pump and timing cover to access the timing set, it's the perfect time to replace the timing cover gasket, front crankshaft seal, and water pump gaskets. Consider replacing the water pump itself if it's old.
Technical Specifications
Varies by engine (225 Slant-6, 318 V8, 360 V8). Most common replacements are for the Chrysler LA-series small block V8s. Sets include a camshaft sprocket, crankshaft sprocket, and timing chain. Performance sets may be double-roller type and offer multiple keyways for timing adjustment.
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- 🛍️ Shop This Part
- Is Your Trailduster's Timing Chain on its Last Legs?
- Key Failure Point: Nylon Cam Gears
- Symptoms of a Failing Timing Set
- Choosing the Right Aftermarket Timing Set
- Performance & Heavy-Duty Tier
- Standard Replacement Tier
- Pro Tip: Single-Bolt vs. Three-Bolt Camshaft
- Estimated Costs for Timing Set Replacement
- Frequently Asked Questions
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