Balancing the rotating assembly for a small-block Chevy V-8 | Redline Updates - Hagerty Media
Progress continues on our 283 Chevy small-block V-8 rebuild, as Davin heads downstate to our friends at Apex Competition Engines to get the rotating assembly—crankshaft, pistons, rods, bearings, wrist pins, and rings—internally balanced.
Why are we putting so much time and effort into this small-block, you ask? Davin is steadfast. “Because I don’t want it to come apart,” he says, “and the devil, is in the details.”
The starting point is balancing the rods—evening the weight of the large and small ends—by grinding off the weight pads as needed. Then it’s on to weighing to the rings (and you include the bearing because it’s part of the rotating assembly), before moving on to the pistons. Davin explains that each piston receives a “bob weight,” a counterbalance that “represents the weight of the rod and piston assembly, including the rings, and the bearings, and the wrist pins … When you go to spin the crankshaft, you can’t have the rods and pistons flinging around madly—(so) you control it with this bob weight.”
With everything balanced and assembled, it’s time to spin the crankshaft and recheck the weight. As Davin watches nervously, John from Apex shares some bad news: It’s off … by a lot. That’s what Davin assumed might happen, since these pistons are significantly heavier than the stock pistons. “We’re going to need to add weight to the counterbalances to offset that bob weight—and it’s a fair amount, 140 grams.”
Check out how they accomplish that. It’s a fascinatingly meticulous process.
Before we go, Davin considers the vital role that auto technicians play, and he offers this for his RockAuto.com tip of the day: “Whether you’re looking for your first job, or your next career, or whatever it may be, there are local shops around you looking for someone like you.” So go for it, just like our Redline Rebuild guys do each and every week.
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