When it comes to engine building, the focus is always cool stuff like camshafts, pistons, intake manifolds, carbs and EFI setups, headers, and so on. But sitting on the front of your engine are workhorse parts that are almost always out of sight and out of mind. Honestly, no one will ever ask you how you like the harmonic balancer or timing chain cover.
Those seemingly simple parts like the timing chain set, timing cover, harmonic damper, damper bolt, and more are vital to engine performance. Heck, your engine won’t run at all without them. Like anything else, these often forgotten parts are subject to that old adage about “getting what you pay for.” Buy the best you can afford. Most won’t break the bank.
Here are some of those parts I’m using on my Mark IV big block Chevy engine build.
Timing Set
The Summit Racing website shows over 60 different timing chain sets for a big block Chevy. Included in the mix are link belt chain configurations (most commonly found in OEM applications) as well as single and double roller designs.
Link belt chains consist of multiple links secured by small diameter pins. Link belt chains of old were often used with nylon covered gears (sprockets) for noise reduction, and over time they’d fail. Modern high performance link belt timing sets use steel gears top and bottom with no nylon coating so they’re much more reliable.
Roller chains use a roller bushing design that physically rolls across the teeth of the upper and lower timing gears. Single roller chains have one row of links and rollers. Double roller chains have two rows of links and rollers that go over the respective double tooth gear set. A double roller timing set costs more but is more durable and less prone to chain stretch.
Some timing sets are manufactured with chains that are slightly shorter than the OEM chain. Those are designed for engines where the mains have been align-bored. Typically, they are either 0.005-inch or 0.010-inch short.
You can also get timing sets with multiple keyways in the crankshaft gear to degree the camshaft. Some use three keyways, allowing for straight up timing or advance or retard (typically four and eight degrees). Others have multiple keyways that offer more cam timing options. The Rollmaster Gold Series timing set I chose for my engine build can advance or retard the cam up to eight degrees in two-degree increments.
You’ll also find timing sets with a thrust button or bearing to prevent galling between the cam gear and the block. Many roller chain sets have steel gears to eliminate the problem altogether.
Learn more about timing sets in the Basic Tech: Standard vs. Roller Timing Chains article.
Harmonic Damper
The terms harmonic damper and harmonic balancer are used interchangeably. But as a GM engineer told me years ago, “That thing on the front of the engine doesn’t balance anything. It’s designed to dampen internal engine harmonics.” I’ve called them harmonic dampers ever since.
Learn more about what a harmonic damper does and the different types available in these OnAllCylinders articles:
Harmonics 101: Understanding Harmonic Dampers
Dampening Vibrations with Harmonic Dampers
Summit Racing’s website shows lots of harmonic dampers for a Mark IV big block Chevy, many SFI 18.1-approved for racing use. Some have degree marks around the entire circumference of the damper body. Others are degreed before and after Top Dead Center (TDC). Typically, these markings are laser etched to make them easy to read with a timing light.
When purchasing an aftermarket damper, watch for the crankshaft pulley hole combination. You can get them in three-bolt patterns (the most common) or six-bolt patterns. Keyways are another consideration. Most have one keyway, but some have double keyways. Engines that run a crank-driven supercharger will be happier with a double keyway.
Timing Cover
There are lots of timing cover choices for big block Chevy. They range from one-piece steel and aluminum covers to two- and three-piece covers that let you access the camshaft without disturbing the oil pan seal.
Many covers come with a timing pointer. If the one you like doesn’t, get one. They’re indispensable for accurately setting ignition timing. Many are adjustable so you can line them up perfectly with the TDC mark on the harmonic damper.
For a closer look at the parts I used, check out the accompanying photos.







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