![]() ![]() “Double-row sets are not required unless the engine has some very heavy valve spring pressures. “Most modern engines do not require a double-row chain,” says Cale Risinger of Melling. A double-row version of the roller chain was developed for better valvetrain control on performance engines and was often used on performance or truck engines of the time, lending to their popularity as a performance modification, but, in many cases, it wasn’t necessary. The roller chain, which was developed in the ‘60s, was so named because the barrels that contact the teeth on the timing gears are separate components that rotate around the link pins, ultimately reducing friction, meaning less heat and less drag. Over time, they developed a reputation for jumping teeth as they wore, which was in part due to some manufacturers using aluminum gears with nylon teeth because it saved a couple pennies. It was an effective chain for mass produced engines that weren’t intended for high-performance use, but they build heat and create drag. The silent chain, which is a series of links that are contoured to mesh with the gear teeth, is also known as a link belt, or non-roller chain. Their reputation is on the line, and the choice comes down to chains, gears, or belts – each one with distinct differences and pros and cons.ĭifferent styles of timing chains have been utilized over the years, including the silent chain and single and double-row roller chains. Performance engine builders have to make the choice and have to set it up right. But, building an engine is a different story, and timing components take no less consideration than any other component. As long as we get that correct, the computer will do the rest. Of course, we still just line up the marks. We use the correct replacement parts and follow instructions. When it comes to engine repair, as auto technicians, in many ways we have it easy because we don’t have to make decisions on what to use and how to install it. The critical importance of valve timing is not lost to them, and variable valve timing coupled with computer-controlled technology means today’s engines, regardless of where they rank in the performance world, rely on perfect timing for drivability, performance and economy.Įngine timing has become so critical for overall performance, that not only does the computer store a trouble code with even the slightest of deviance from programmed parameters, but determining a timing issue has become one of the more recent diagnostic topics, and the use of cylinder pressure transducers coupled with an oscilloscope allows us to interpret cylinder pressure, and by comparison as well as learned knowledge, we can determine without teardown if there is a timing-related issue. Anything less than perfect timing has never been acceptable in the performance world, and now, it’s not acceptable by auto manufacturers either. Years ago, nothing about the stock engine was that precise anyhow. If you’re replacing a worn-out timing chain or camshaft, your customer will be tickled pink that their engine runs good again, and timing only involves lining up the marks and moving on. As technicians, this isn’t something we do as part of a standard repair, because again, our customer doesn’t care. If you skip the step, aside from the potential of engine damage, there’s a very likely potential for power loss, and while it might be comparatively minor, it’s just not acceptable. As engine builders know, degreeing a cam is critical for a high-performance build. ![]() One of the primary factors is engine timing. In the context of engine performance, the same is true, and though most vehicle owners don’t care, as technicians we can easily draw parallels between an everyday driver and the high-performance characteristics that are associated with their engines. The interesting aspect of modern vehicle technology is that much of it, as it relates to performance, is a result of lessons learned from racing. ![]()
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