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.

Rollmaster Gold Series timing set for big block Chevy
Timing sets are available in one of three basic types—link belt chain, single roller, and double roller. The materials used for the crank and cam gears (sprockets) range from cast iron to steel to billet steel. This Rollmaster timing set I’m using in my big block Chevy is a double roller arrangement, which means there are two sets of teeth on each gear and corresponding links on the chain. The set also features billet steel crank and cam gears. (Image/Wayne Scraba)
Timing set crank sprocket with adjustable keyway
Many timing sets have options for adjusting camshaft timing including offset bushings (for the cam pin), offset keys (for the crank keyway), multiple keyways, and adjustable cam gears. My Rollmaster timing set has multiple keyways so I can advance or retard the cam up to eight degrees in two-degree increments. (Image/Wayne Scraba)
PowerBond harmonic damper for big block Chevy
Harmonic dampers aren’t glamourous, but engine damage like worn bearings, shorter valve spring life, broken timing chains, and even crankshaft failure will happen without one. This PowerBond harmonic damper is built with a CNC-machined billet steel hub coupled to a steel ring with a special rubber material that acts as the vibration damper. It’s lighter than a similar factory cast iron harmonic damper but is spin-tested to 21,000 RPM and has an SFI 18.1 rating for racing use. (Image/Wayne Scraba)
Degree marks on PowerBond harmonic damper
While most OEM harmonic dampers have a single timing mark for Top Dead Center, many aftermarket examples like this PowerBond damper have partial or full 360-degree timing marks etched into the outer ring. This is great feature when it comes to lashing valves and setting ignition timing. (Image/Wayne Scraba)
Milodon timing cover for big block Chevy
Unless you have a high-end belt drive, you need a cover to protect your timing set. This is a one-piece Milodon steel timing cover for my big block Chevy. There are plenty of other options available including aluminum covers and two- and three-piece covers that let you access the camshaft without disturbing the oil pan seal. That’s a big plus if you want to adjust cam timing to find more horsepower or better throttle response (Image/Wayne Scraba)
CVR adjustable timing pointer for big block Chevy
Something else you’ll need up front is a timing pointer. You use a simple fixed timing tab or an adjustable pointer like this one made by CVR. It’s made from billet aluminum and can be adjusted up to four degrees so you can line it up perfectly with the TDC mark on the harmonic damper. That helps ensure more accurate ignition timing. (Image/Wayne Scraba)
ARP cam bolts, timing cover bolts, and balancer bolt for big block Chevy
You’ll need hardware like cam bolts, timing cover bolts, and a harmonic bolt. I used ARP bolts for my big Chevy. They’re made from top-quality steel and precision made so I never have to worry about fastener failure. Something else you might want to consider is a cam locking plate. The plates have bendable tabs that fit against the cam bolts so they won’t back out on you. It’s cheap insurance. (Image/Wayne Scraba)

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Author: Wayne Scraba

Wayne Scraba is a diehard car guy and regular contributor to OnAllCylinders. He’s owned his own speed shop, built race cars, street rods, and custom motorcycles, and restored muscle cars. He’s authored five how-to books and written over 4,500 tech articles that have appeared in sixty different high performance automotive, motorcycle and aviation magazines worldwide.