Engine Timing Set Replacement Guide for 1979-1987 GMC C1500
Keep your classic GMC's engine running strong by replacing a worn or failed timing set.
- The original factory timing set on many V8 engines used a failure-prone nylon cam gear that should be replaced.
- Aftermarket timing sets from brands like Cloyes, Melling, and Edelbrock are a significant durability upgrade.
- Symptoms of failure include engine rattle, loss of power, and misfires.
- It is highly recommended to replace the water pump and timing cover seals at the same time.
Is Your GMC C1500's Timing Set Failing?
For 1979-1987 GMC C1500 trucks, especially those with V8 engines, the original timing set is a known weak point. Many of these engines came from the factory with a camshaft gear that had nylon-coated teeth. This was done to make the engine run quieter. Over decades of use, the nylon becomes brittle, cracks, and can break off. These plastic pieces can fall into the oil pan and clog the oil pump pickup screen, which can lead to major engine failure. Even before that happens, a worn chain or damaged gear teeth will cause the ignition and valve timing to become inaccurate, leading to poor performance.
Symptoms of a Bad Timing Set
🎬 Watch this video to see common signs of timing chain failure.- Engine Rattle: A loose timing chain can make a rattling or clattering noise, especially when the engine is idling or first started.
- Poor Performance: A stretched chain can retard the timing, making the truck feel sluggish and underpowered.
- Engine Misfires: If the chain has enough slack to jump a tooth on one of the gears, the timing will be severely off, causing the engine to misfire or run very rough.
- Metal Shavings in Oil: When the gear teeth or chain wear down, small metal or plastic pieces can end up in the engine oil and oil pan.
- Engine Won't Start: In a worst-case scenario, a broken chain will prevent the engine from starting at all 🎬 Learn how to diagnose and replace a Chevy 350 timing chain. and can cause catastrophic damage if the pistons hit the valves.
Choosing the Right Aftermarket Timing Set
For this generation of GMC trucks, aftermarket timing sets are almost always an upgrade over the original equipment. They replace the failure-prone nylon-toothed cam gear with a durable all-metal gear. When shopping, you'll see a few common types.
Brand & Quality Tiers
Your choice depends on your truck's use and your budget.
- Good (Standard Replacement): Brands like Cloyes (standard line) and Melling offer excellent quality, durable replacements for a daily driven or stock truck. These kits feature all-steel gears and are a significant upgrade over the original nylon components. They provide reliability for tens of thousands of miles.
- Better (Heavy-Duty): For those who tow, haul, or want extra peace of mind, a heavy-duty or "true roller" set is a great choice. Brands like Cloyes, Melling Select Performance, and Edelbrock offer these. They often feature a double roller chain, which is stronger and provides more precise timing than a standard single roller or link-belt style chain.
- Best (Performance/Adjustable): If you have a modified engine with a performance camshaft, an adjustable timing set from a brand like Edelbrock or Cloyes is ideal. These have multiple keyways on the crankshaft sprocket, allowing you to advance or retard the cam timing to optimize performance.
Pro Tip: Double Roller Clearance
When upgrading to a wider double roller timing chain, you may need to check for clearance. On some small block Chevy engines, you might have to slightly grind a boss inside the timing cover area for the chain to fit without rubbing. Always check for proper clearance before final assembly.
Estimated Costs for Timing Set Replacement
The cost will vary based on the parts you choose and whether you do the work yourself. Labor costs for this job are significant due to the need to remove the radiator, water pump, and harmonic balancer to access the timing cover.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Timing Set | $25 - $215 |
| Shop Labor | $400 - $750 |
| Total Professional Replacement | $425 - $965 |
Frequently Asked Questions (FAQ)
Do I need to replace my timing set if it's not making noise?
If your engine is high-mileage and has the original nylon-toothed gear, it's a good idea to replace it proactively. The nylon can fail without warning. If you're already doing work that requires removing the timing cover, like replacing the camshaft or water pump, you should absolutely replace the timing set at the same time.
What is the difference between a single roller and a double roller chain?
A double roller chain is wider and has two rows of rollers, making it stronger and more resistant to stretching than a standard single roller or link-belt chain. It's a popular upgrade for performance and durability.
Should I replace the water pump and other parts at the same time?
Yes. The water pump must be removed to get to the timing cover, so it's the perfect time to replace it. You should also inspect the harmonic balancer for damage and replace the timing cover seal and water pump gaskets.
Is an adjustable timing set necessary for a stock engine?
No, an adjustable set is not necessary for a stock engine. It's designed for performance engines where fine-tuning camshaft timing is needed to maximize power. A standard, non-adjustable set from a quality brand is perfect for a stock rebuild.
Are there any recalls for the timing set on my truck?
No, there are no active or historical recalls specifically for the engine timing set on 1979-1987 GMC C1500 trucks. The common issue with original nylon gears was addressed by aftermarket parts manufacturers decades ago.
Helpful Videos
Technical Specifications
Vehicle may have been originally equipped with a single-row 'silent' type chain and a nylon-coated camshaft sprocket. Aftermarket replacements are available in single roller, double roller, and adjustable multi-keyway configurations with all-metal 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.