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Old 05-25-2011, 07:08 PM
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can i stroke a sbc400

Can you build a 383 stroker with a 400 block/350 crank? If so, what size connecting rods???

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Old 05-25-2011, 07:23 PM
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Originally Posted by stevetankl
Can you build a 383 stroker with a 400 block/350 crank? If so, what size connecting rods???
Using a +0.030" bore 400 block and a 350 crank will yield a 377. Using a +0.030" 350 block with a 400 crank will yield a 383. Nobody in his right mind de-strokes a 400 unless he wants the breathing of a large bore and also needs less cubic inches to fit into a class restriction for racing, normally based on lbs per cubic inch.

You can use any length rod you want, 5.565", 5.700", 6.000" or whatever, but you have to use the correct piston compression height to work with the stroke and rod length. A common "stack" when building these 383 motors will be 9.000", where the crank radius is 1.875", the rod is 5.700" and the piston is 1.425". Add these components together and find 9.000". If you used the 400 crank with a 6.000" rod, you would have to reduce the piston compression height to 1.125". (1.875" + 6.000" + 1.125" = 9.000"). The stack you use must fit into the block without pushing the piston crown out of the bore so that it would hit the cylinder head. Nominal block deck height (stock) is 9.025".

There is also "squish" to contend with. As the piston comes up in the bore to top dead center on the compression stroke, it is good to have the piston come very close to the underside of the cylinder head in order to squish out the fuel/air mixture that is opposite the chamber. This "jetting" of mixture across the chamber creates turbulence that homogenizes the mixture and eliminates lean and rich pockets of mixture in the chamber so that you get a more complete burn. This squishing of the mixture will reduce the chances of detonation as well. Most fellows find that the motor will tolerate a lesser quality of fuel with a good, tight squish of 0.035" to 0.045" on a small block. This is the dimension from the crown of the piston to the block deck (piston deck height) plus the thickness of the head gasket. For instance, if the piston deck height is 0.010" and the gasket is 0.028", the squish would be 0.038".

Last edited by techinspector1; 05-25-2011 at 07:38 PM.
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