A Practical Guide to the 1979-1987 GMC C3500 Engine Timing Set
Keep your classic GMC's engine running strong by understanding its timing set needs.
- Listen for a rattling noise from the front of the engine; it's the most common sign of a failing timing chain.
- Upgrade from the original nylon-toothed cam gear to an all-metal set from a brand like Melling or Cloyes for much better durability.
- For heavy-duty use or performance, a double roller timing set is a worthwhile investment.
- Always plan to replace the water pump, timing cover gasket, and front crank seal at the same time to save on future labor.
Is Your C3500's Timing Chain Failing?
A worn timing chain on your GMC C3500 can cause serious problems. These trucks are known for their durability, but the original timing sets, especially those with nylon-coated camshaft gears, can fail with age. When the chain stretches or the gear teeth wear down, the engine's timing becomes incorrect, leading to poor performance and eventually, a no-start condition. Listening for the early signs of failure is key.
Key Symptoms to Watch For:
- Engine Rattle: A rattling or clattering noise from the front of the engine, especially when idling or on startup, is a classic sign of a loose timing chain slapping against the timing cover.
- Engine Misfires and Rough Idle: If the chain has stretched and "jumped a tooth," the camshaft and crankshaft will no longer be synchronized. This throws off the engine timing, causing a rough idle, misfires, and backfiring.
- Loss of Power: Your truck may feel sluggish and have trouble accelerating because the valve timing is no longer optimal for performance.
- Metal Shavings in Oil: During an oil change, you might notice tiny metal shavings in the drained oil. This can be a sign that the timing chain or gears are wearing down and shedding material.
Critical Warning
If you suspect your timing chain is failing, do not continue to drive the vehicle. A chain that breaks or jumps several teeth can cause the pistons to collide with the valves, resulting in catastrophic and expensive engine damage. It is much cheaper to replace a timing set than to rebuild an entire engine.
Choosing the Right Aftermarket Timing Set
For a vehicle of this age, aftermarket parts are the most common and practical choice. The quality can range from basic stock replacements to high-performance racing sets. For a workhorse like the C3500, durability is the most important factor.
| Brand Tier | Brands | Description & Quality Assessment |
|---|---|---|
| Standard Replacement | Cloyes, Melling | Both Cloyes and Melling are well-respected names for timing components. They offer standard replacement sets that are a good upgrade from the original nylon-toothed gears. For a daily driver or light-duty truck, their all-metal, silent-chain style sets are a reliable and affordable choice. Some users have reported issues with slack in lower-end Cloyes sets, making Melling a slightly more consistent choice for standard replacements. |
| Heavy-Duty / Performance | Melling Select Performance, Edelbrock, Cloyes Performance | For heavy towing, high-mileage, or modified engines, upgrading to a heavy-duty set is a smart investment. These often feature a "double roller" chain, which is stronger and more durable than a standard "silent" or single roller chain. Brands like Edelbrock and Melling's performance line offer sets with billet steel gears and high-strength chains that provide maximum accuracy and longevity. |
| OEM Supplier-Tier | INA | INA is a major OEM supplier for many manufacturers, particularly European brands, and is known for quality bearings and tensioners. While they offer timing components, they are less common in the traditional American V8 market. Their quality is generally considered high, but brands like Melling and Cloyes have a more established track record specifically for GM trucks of this era. |
Mechanic's Pro Tip
When replacing the timing set, it is highly recommended to also replace the timing cover gasket, front crankshaft seal, and the water pump. These components are all located in the same area, and replacing them at the same time saves you from having to do the same labor-intensive job twice down the road.
Frequently Asked Questions (FAQ)
What's the difference between a single roller and a double roller chain?
A double roller chain is wider and has two sets of rollers, making it stronger and more resistant to stretching than a single roller or a standard "silent" link-belt chain. For the V8 engines in a C3500, a double roller is a popular and worthwhile upgrade for durability, though it may require minor clearance modifications inside the timing cover.
Do I need to use a timing light after replacing the timing set?
Yes, absolutely. After installing the new chain and gears, you must verify and adjust the ignition timing. For most of these trucks, this involves disconnecting the electronic spark advance wire (usually a single brown wire near the firewall) and using a timing light aimed at the harmonic balancer to set the base timing. Failure to do this will result in poor performance and potential engine damage.
Are there any recalls for the timing set on these trucks?
No, searches of the National Highway Traffic Safety Administration (NHTSA) database show no recalls specifically for the engine timing set on 1979-1987 GMC C3500 trucks. Any failures are considered a result of normal wear and tear due to the vehicle's age.
Should I get a set with adjustable timing?
For most stock or mildly modified engines, a standard, non-adjustable timing set is sufficient. Adjustable timing sets, which have multiple keyways on the crankshaft sprocket, allow for advancing or retarding the camshaft timing. This is a feature used by engine builders to fine-tune performance and is not necessary for a standard repair.
Technical Specifications
The most common engines are the 5.7L (350ci) Small Block V8 and the 7.4L (454ci) Big Block V8. While parts are similar, ensure you select a kit specified for your exact engine. Key choices include standard 'silent' chains versus more durable 'double roller' chains. Most original camshaft sprockets had nylon-coated teeth for quiet operation, which are prone to failure and should be replaced with all-metal sprockets.
We Have This Part in Stock
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.