Mercury Comet Engine Timing Set Replacement Guide (1960-1977)
Keep your classic Comet's inline-six or V8 engine running strong and in-sync with the right new timing set.
- Identify your engine first; timing sets for inline-six and V8 engines are not interchangeable.
- Symptoms include engine rattle, rough running, and power loss; do not ignore these signs.
- Any aftermarket all-metal timing set is an upgrade over the original nylon-toothed V8 cam gears.
- For performance V8 builds, consider a stronger double roller chain from brands like Ford Performance or Edelbrock.
Is Your Comet's Timing Off? Signs of a Failing Timing Set
An engine's timing set wears out over time. The chain can stretch, or the teeth on the gears can wear down. For classic Ford V8s, the original camshaft sprockets often had nylon-coated teeth that become brittle and break apart over time, making an all-metal aftermarket replacement a smart upgrade. Listen and feel for these common symptoms:
- Rattling or Slapping Noise: The most common sign is a rattling sound from the front of the engine, especially noticeable at idle or on startup. This is the sound of a loose timing chain slapping against the inside of the timing cover.
- Engine Misfires and Rough Idle: As the chain stretches, it can retard the camshaft timing. This throws off the engine's rhythm, causing it to run rough, misfire, or stall.
- Loss of Power: An engine with incorrect cam timing will feel sluggish and won't accelerate as it should.
- Metal Shavings in Oil: During an oil change, you might see small, shiny metal particles in the used oil. These can be bits of the timing gears or chain wearing away.
Critical Failure Warning
If a timing chain breaks completely, the engine will stop running immediately. While most Comet V8 and inline-six engines are 'non-interference' at low RPMs (meaning the pistons won't hit the valves), a failure at high RPM can still cause catastrophic damage. Do not ignore the warning signs.
Choosing the Right Aftermarket Timing Set
For a vehicle from this era, new aftermarket parts are the standard for replacement. Original equipment (OEM) parts are no longer in production. The key is choosing the right set for your specific engine—the inline-six and V8 parts are very different and not interchangeable.
Standard & Heavy-Duty Replacements (All Engines)
These brands offer quality, stock-style replacements that meet or exceed original specifications. They are perfect for daily drivers and stock restorations.
- Melling: Widely respected for quality, especially their oil pumps. Forum users and mechanics often report good experiences with the fit and durability of Melling timing sets.
- Cloyes: A long-standing name in timing components. While some modern engine builders have noted quality control issues, their traditional pushrod engine sets are generally considered reliable.
Performance Upgrades (Mainly V8 Engines)
If you are rebuilding your V8 for more power, a performance timing set is a worthwhile investment. These often feature stronger 'double roller' chains and adjustable sprockets.
- Ford Performance: Offers high-quality double roller timing sets for small-block Fords (289/302). Many kits include a multi-index crank sprocket, allowing you to advance or retard cam timing for performance tuning.
- Edelbrock: Known for performance parts, Edelbrock offers 'True Roller' timing sets for Ford small blocks. They use durable materials like billet steel for the crank sprocket to reduce chain stretch and improve timing accuracy.
Pro Tip: Double Roller vs. Single Roller
A 'double roller' chain is wider and stronger than a standard 'silent' or single roller chain. For V8 engines, especially those being modified for more power, a double roller set from a brand like Edelbrock or Ford Performance provides extra strength and timing stability. For most inline-six engines, a quality stock replacement set is sufficient.
Estimated Costs for Timing Set Replacement
| Item | Estimated Cost |
|---|---|
| Aftermarket Timing Set (Standard) | $30 - $75 |
| Aftermarket Timing Set (Performance/Double Roller) | $80 - $155 |
| Shop Labor | $600 - $1,200 |
Note: Costs are estimates and can vary based on your location, vehicle condition, and the specific parts chosen.
Frequently Asked Questions
Do I have a timing chain or timing gears?
Most 1960-1977 Mercury Comets with V8 engines (260, 289, 302) use a timing chain and sprocket set. Later inline-six engines (some 170, 200, 250) also use a chain. Some very early inline-six engines may have used fiber gears, which should always be upgraded to an all-metal gear or chain set during replacement.
Should I replace the water pump and seals at the same time?
Yes. Replacing the timing set requires removing the water pump and timing cover. Since you already have it apart, it is highly recommended to install a new water pump, timing cover gasket, and front crankshaft seal to prevent future leaks and save on labor down the road.
Is a double roller timing set better for my V8?
For a stock or mildly modified engine, a quality standard replacement chain is perfectly fine. If you are building the engine for high performance, a double roller chain offers superior strength and durability, making it a smart upgrade.
Do I need special tools for the job?
Yes, the most important special tool is a harmonic balancer puller, which is required to remove the main pulley from the crankshaft. These can often be rented from auto parts stores. You will also need a good socket set, a torque wrench, and gasket scrapers.
Technical Specifications
Varies by engine. Common configurations include single roller ('silent') chains, double roller chains, and gear sets. V8 sets typically include one camshaft sprocket and one crankshaft sprocket. Inline-six sets may be gears only or include a chain and sprockets.
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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 Comet's Timing Off? Signs of a Failing Timing Set
- Critical Failure Warning
- Choosing the Right Aftermarket Timing Set
- Standard & Heavy-Duty Replacements (All Engines)
- Performance Upgrades (Mainly V8 Engines)
- Pro Tip: Double Roller vs. Single Roller
- Estimated Costs for Timing Set Replacement
- Frequently Asked Questions
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