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Priority Oiling Main System - Ask Anything

Jeff Smith: Wow, it's been a while since I've answered a question about the 283ci small-block Chevy. These are great little engines with a 3.875-inch bore and a short 3.00-inch stroke. Because they are displacement challenged, they don't make much in the way of low-speed torque. Most of these engines were backed by a Powerglide two-speed automatic, with a few manual transmission applications. This is an internally balanced engine, meaning that the flywheel, regardless of diameter, is a zero balance. All production small-block Chevys with a two-piece rear main seal, except for the 400ci small-block, were internally balanced engines. So given that, you can easily add a larger flywheel to a 283 without a balance issue. There are two basic small-block Chevy flywheel diameters, identified as either 153-tooth or 168-tooth. The smaller 153-tooth wheel typically used a 10.5-inch-diameter clutch disc, while the larger, 168-tooth wheel utilized an 11-inch-diameter clutch disc. The two flywheels (or flexplates when used with automatics) also require two different starter motor bolt patterns. The simple way to identify the starter motors is to look at the bolt patterns that attach the starter to the block. The starter motor intended for use with the smaller, 153-tooth flywheel will have two boltholes in parallel. The larger, 168-tooth flywheel starter motor pattern will use offset boltholes.

There are two things that will affect the use of a larger flywheel. First is the bellhousing size. Most small-block Chevy bellhousings we've run across are designed to be used only with the smaller, 153-tooth flywheel. There are factory bellhousings intended for small-block use with a 168-tooth flywheel, but they are relatively rare. You mentioned that you already have a larger bellhousing, so that shouldn't be an issue. The other potential problem is that since the 283 never came from the factory with a 168-tooth flywheel, it's likely the block will be drilled only for the parallel starter motor bolt pattern. The solution is to either drill the block for the offset bolt pattern or use an aftermarket gear reduction starter motor. Of those two solutions, the least expensive is to drill the block. If you are going that route, make sure the starter motor gear is properly lined up with the flywheel. The best way to do that is to remove the solenoid from the starter and engage the starter drive teeth with the flywheel to ensure the teeth line up. Then mark the hole with a transfer punch and drill and tap. This is much easier if the engine is not in the car, but it can be done in the vehicle if you are careful. You may even want to use an old starter motor nose piece as a drill guide.

What may be the biggest consideration is overall weight of the flywheel and clutch assembly. Keep in mind that your 283 doesn't make a lot of torque. In the small-cubic-inch gasser days, one way to get those little motors to launch was to fit them with a heavy flywheel, rev them to the moon on the starting line, and use the inertia force of all that spinning mass to help launch the car. We're not saying this was an efficient way of doing things, but it was fun to watch! This is hardly a practical way to drive a car on the street, which means a heavier flywheel will not accelerate as quickly as a lighter unit. You need some kind of compromise between too heavy and too light because an overly light system (like an aluminum flywheel) will accelerate very nicely but is a major pain to drive on the street because it lacks sufficient weight to store enough energy to move the car from a dead stop. So some compromise between papa bear at too heavy and baby bear at too light is what you need. A typical 10 1/2-inch flywheel, clutch, and pressure plate will weigh around 40 to 45 pounds. An 11-inch flywheel probably won't weigh significantly more, but it's worth weighing both just to make sure.

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