Stay with the stock 1 pce crank balance arrangement
You get to use the flexplate you already have and if you need a replacement anytime it can be bought at any parts place.

You may find you have ad amaged forged crank in your engine. Some people are wary of changing forged ranks for cast cranks, believing cast ones to be inferior. Unless you have a very high-performance small-block Chevy, this really isn't the case. For applications up to 6500 rpm, the cast crank is as good, possibly even superior to teh forged crank. They seem to suffer less breakage and last at least as long in terms of wear. SO if you find a cast crank in good condition, have no hesitation in using it in your engine so long as it has main- and rod-journal sizes which will work with your block and rods. The stroke length must also be the same as the one you are replacing as well.

If you find you need another crank as well as a rebore, you can use any stroke length you want as long as the crank physically fits int eh block. The pistons used must then be those with teh correct piston pin (wrist pin) to crown height. This is known as the compression height. Be sure you get pistons to match teh stroke of teh crankshaft. Rods may also need to be changed as some differences exist, as explained in the following paragraph...

Crankshafts: cast or forged?

You may have heard that a forged crank is the way to go. You heard correctly, but his should in no way imply that Chevrolet's cast cranks are second best. Far from it. Chevrolet forged cranks are good, but the cast cranks are, for many applications, just as good, and in some instances, better. Properly prepped, a cast crank is fine in a circle-track motor of 400-plus horsepower, and I've seen them survive 200 passes down the strip in motors making 600 horsepower. Although the latter may be an extreme, and a certain amount of luck may be involved, it does show that they are relatively stout pieces.

Cracked forged cranks show up at the rate of about 10 to every cast crank. this means that if you have a forged crank, it's imperative it be crack tested and discarded ifa ny cracks are revelaed. Althoguh cast cranks havel ess outright strength than steel forgings, they have more internal damping. Unlike steel, they do not "rin" as easily and, as a result if they're not stressed to their limit, the fatigue/wear life is as good or better. Althoguh they may be made of a material only 65 percent of thes trnegth of a stock chevy forged crank, they last and deal with stresses as if they were more like 80 percent of the strenght. Also, cast iron has better wear properties than a non heat-treated steel so it can last significantly longer. With a good damper, a cast crank is fine in a 450-horsepower street motor and remembering that most quoted horsepower numbers are inflated, 450 genuine horsepower makes any street car into a flyer.

If you buy a Scat cast steel crank to build a 383, it will ahve zero time on it, and from the right source it will cost about 425 to 450 percent of the cost of a straight 350 regrind. You can see how the economics are shaping up.

In 1998 dollars, a Scat crank costs about $175 more than a stock crank regrind. This additional outlay in a .030 over block delivers 28 more cubic inches. If you build to the book(this book, that is) you are unlikely to see less than 1.1 lb-ft of torque per cube with 1.2 to 1.25 being more common. This means the additional outlay of $175 delivers between 30 to 34 extra lb-ft, with most of this icnrease showing up in the usable rev range. That works out to about $5.50 per lb-ft increase.

That's less than 40 percent of the cost per lb-ft of that delivered by a typical bolt-on blower installation. Assuming a moderate cam that allows peak power at 6000 RPM, the extra inches provided by the crank are worth between 34 and 40 horsepower. If it's a race application, the advantages of a longer-stroke crank in a 35- don't stop there, espeically if your budget means using production-type heads with a low set plug position.

Bigger displacemetn means teh ability to achieve a higher compression ratio without compromising the chamber shape with excessively high piston crowns. Often it's possible to achieve the desired ratio with cheaper and lighter flat top pistons. Having a better chamber in a 13/1 motor alone can account fora minimum of 10 additional horsepower. In terms of performance, the Scat 383 crank looks like a winner but you may be asking just how good can a crank be for costing appreciably less than a new cheavy cast crank?

I asked that question of an umber of engine builders before I put one of those cranks into my motor. This was not because I thought the cranks may be aof less strength than the stock cast crank, but because I've built low-cost engines that made four-figure horsepower numbers and stock parts broke. Scat has built a reputation based on quality over a period of more than 30 years, and the boss Tom Lieb isnt about to throw that away.

Unlike cheap cranks, every Scat crank goes through an inspection routine to check bearing finishes and sizes similar to that of the $2500 race cranks it makes. As a supplier for professional TOp Fuel and Trans Am among others, the company knows what it takes to make a crank live. I needed to know at what level I might expect failures. To this end I spoke to Bill Smith at Speedway Motors in Nebraska. At the time Smith had used more than 3000 of these cranks in budget/claimer race engines at power levels up to 550 horsepower and RPM to about 8,000 and had not seen one failure attributable to a Scat cast-steel crank. At the time of this writing, I've built more than 650 horsepower nitrous-injected race motors on Scat cast cranks and I'm still no closer to knowing where the line is drawn.