It worked to a certain degree, but as you can well imagine, it wasn’t exactly robust. Initially, the racing fix was to eliminate gear drives, and believe it or not, use a timing chain set with a nylon upper gear (this was a common Chevy production component at the time). It actually dampens the harmonics after it passes through the lower cam gear. Remember the damper is outbard of the timing chain or gear drive on the engine. What about the harmonic damper (balancer)? Doesn’t it stop this internal nonsense? Not exactly. You can imagine what this does to the dynamics of the valve train. This meant that every pop, bang and boom seen by the crank went straight to the cam. To make matters worse, the only option back then was a gear drive, and it had a tendency to physically tie the crankshaft to the camshaft even more ardently than a timing chain. It was no big step to discover this harmonics dilemma eventually had a profound effect upon valve and spark timing – to the point where racers had (and in some cases, still have) a difficult time holding the timing stable in their engines.
SMALL BLOCK CHEVY TIMING BELT VS TIMING CHAIN PRO
Why have belts eclipsed timing chains and gear drives in both Sportsman and Pro motorsports? The real key is harmonics.įirst, let’s rewind: Decades ago, a few very savvy racers (Dan Jesel was one of them) noticed there was a considerable amount of harmonics, vibration, and resonance transmitted from the crankshaft to the camshaft. One of the big benefits of a belt drive is the ease of camshaft tuning (phasing), but we’ll look at that in a minute. In fact, you regularly see belt drives in everything from drag race Super Stockers to Pro Stockers (and a lot in between – including endurance applications such as Winston Cup and road race applications). What has replaced them (where legal by the rules) is the timing belt. They obviously get the job done, but they’re not 100% infallible.
Not that long ago, you had two choices when it came to cam drives for your race engine – a timing chain or some sort of gear drive.
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