A Guide to the Engine Timing Set for the 1971-1976 Plymouth Scamp
Keep your classic Scamp's Slant-6 or V8 engine running strong by choosing the right replacement timing set.
- You must verify if your Scamp has a Slant-6 or a 318 V8 engine before ordering, as the parts are different.
- Upgrading to an all-metal, double-roller timing set is a common and recommended reliability improvement over the original design.
- A rattling noise from the front of the engine is the most common symptom of a worn timing chain.
- While you are replacing the timing set, it is highly cost-effective to also replace the water pump and front crankshaft seal.
Is Your Plymouth Scamp's Timing Chain Failing?
On a classic car like the 1971-1976 Plymouth Scamp, the original timing set has likely seen a lot of miles. The timing chain can stretch over time, and the gear teeth wear down. This is especially true for V8 models that originally came with a camshaft gear that had nylon-coated teeth, which can become brittle and break apart. When the timing set wears, it can cause several noticeable problems.
Symptoms of a Worn Timing Set
- Rattling Noise: The most common sign is a rattling or clattering sound coming from the front of the engine, especially at idle or on startup. This is the sound of the loose, stretched chain slapping against the inside of the timing cover.
- Poor Engine Performance: A stretched chain retards the camshaft timing, which can lead to a noticeable loss of power, sluggish acceleration, and poor throttle response.
- Rough Idle or Misfires: Inconsistent valve timing can make the engine idle roughly or misfire.
- Hard Starting: If the timing is off, the engine may be difficult to start.
- Metal Shavings in Oil: In severe cases, pieces of the worn gears or chain can break off and end up in the engine oil. Finding metallic particles during an oil change is a serious warning sign.
Pro Tip: A mechanic can quickly check for a loose timing chain. With the engine off, they can remove the distributor cap and turn the crankshaft pulley back and forth by hand. Watching how many degrees the pulley turns before the distributor rotor begins to move shows how much slack is in the chain. More than 4-5 degrees of slack suggests the chain is worn and should be replaced.
Choosing the Right Aftermarket Timing Set
For a vehicle from the 1970s, new original equipment (OEM) parts are generally not available. The good news is that modern aftermarket timing sets are often a significant upgrade over the original factory parts, especially when moving from a stock single chain with nylon gears to an all-metal, double-roller setup.
The first and most important step is to correctly identify your engine. The 1971-1976 Scamp was primarily available with two different engines, and they use completely different timing sets:
- Slant-6 (198 or 225 cubic inch)
- 318 cubic inch V8
Always verify your engine before ordering parts. Once you know your engine, you can choose a brand and type.
Brand Quality Tiers
- Good (Standard Replacement): Standard replacement sets from brands like Cloyes or Melling offer quality comparable to or better than the original. They typically feature a standard "silent" type or single roller chain and metal sprockets, which is a durable solution for a daily driver.
- Better (Heavy-Duty): For more durability, look for an all-metal, heavy-duty single roller or double roller timing set. Brands like Cloyes and Melling are well-regarded in the Mopar community. These are excellent choices for most Scamp owners.
- Best (Performance): For performance builds or maximum durability, a Melling Select Performance or similar premium double-roller timing set is the top choice. These often feature billet steel gears and high-strength chains designed to handle higher RPM and stress. An upgrade to a double-roller chain is a very common and recommended modification for the 318 V8.
A Note on Brands: Cloyes has long been a top name for American engines. However, some recent online reports from DIY mechanics have shown instances of new Cloyes sets having excessive slack out of the box. Melling is another legacy brand with a strong reputation, and some users have reported better results with their sets recently. Both are generally considered quality choices.
Estimated Replacement Costs
The cost to replace the timing set on a 1971-1976 Scamp is much more affordable than on a modern vehicle, as the engine design provides easier access.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Timing Set | $32 - $168 |
| Shop Labor | $375 - $625 |
| Total Estimated Cost | $407 - $793 |
Cost estimates are for parts and labor and do not include taxes, fees, or costs for other recommended repairs.
Frequently Asked Questions (FAQ)
Should I replace the water pump and other parts at the same time?
Yes. The replacement job requires removing the water pump and harmonic balancer to get to the timing cover. Since the labor is already being done, it is highly recommended to also replace the water pump, the front crankshaft seal in the timing cover, and any coolant bypass hoses. This is very cost-effective and prevents having to do a similar job again soon.
What is a double-roller timing chain and do I need one?
A double-roller chain is physically stronger than a standard single-row or "silent" chain. It has two rows of rollers and links, making it more durable and less prone to stretching. For a stock Slant-6 or 318, it is a worthwhile but not essential upgrade. For any engine that has been modified for more power, it is a highly recommended upgrade for reliability.
Is this a good DIY job?
For a home mechanic with some experience, this is a manageable job. It does not require dropping the engine. However, it does require specific tools like a harmonic balancer puller and installer. Attempting to remove or install the balancer without the correct tools can cause serious damage to the crankshaft or main bearings.
How do I know if I have a Slant-6 or a 318 V8?
The easiest way to tell is by looking at the engine. A Slant-6 is an inline-six-cylinder engine, meaning all six cylinders are in a single line. It is famous for being physically tilted to one side (the "slant"). A 318 is a V8, with two banks of four cylinders in a "V" shape. The timing sets for these two engines are not interchangeable.
Technical Specifications
Primary engine applications: Chrysler Slant-6 (198/225 cid) and Chrysler LA V8 (318 cid). Aftermarket options include standard replacement 'silent' chains, single-roller chains, and heavy-duty double-roller chains. Performance sets often feature billet steel sprockets and multiple keyways for adjustable cam timing.
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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.