383 Stroker Specifications

by Jennifer Reed
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The 383 stroker engine is typically installed in a vehicle to increase horsepower and torque. The GM small block 5.7-liter 350 is the base for the 383 stroker; the 350 crankshaft is exchanged for a GM small block 400 crankshaft. The 400 crankshaft rod journals produce a longer stroke for the engine and create a larger displacement. Professional machining of the engine is required.

Displacement Calculation

The 383 stroker engine has a bore of 4.03 inches and a stroke of 3.75 inches versus the GM 350's bore of 4.00 inches and 3.48 inches of stroke. The 383 cubic inches are calculated by the following formula: the bore of 4.030 is multiplied by the bore of 4.030 then multiplied by the stroke of 3.75 then multiplied by 0.7854, then multiplied by the eight cylinders to equal 382.668. This total is then rounded up to the displacement figure of 383 inches.

Machine Work Required

The small block 400 crankshaft will need to be machined to fit the small block 350 engine block. The machine shop will turn down the journals of the crankshaft to achieve proper fitment into the saddles of the 350 engine. The engine block will need to be bored 0.030 over its original size to create proper clearance and displacement. The longer stroke of the small block 400 crankshaft will require a better clearance to prevent severe wear of the rods and cylinders.

Torque Specifications

The two-bolt main engine block main caps torque is 70 foot-pounds. For the four-bolt main block the torque wrench should be set to 70 foot-pounds for the inner main cap bolts and 65 foot-pounds for the outer main cap bolts. The connecting rods with the 3/8 bolts will need to be torqued to 45 foot-pounds. The connecting rods with the 11/32 bolts should be torqued to 35 foot-pounds. The cylinder head bolts are to be torqued to 65 foot-pounds. Torque the oil pump bolt to 65 foot-pounds and the oil pan to 12 foot-pounds. Torque the timing Cover to 6 foot-pounds and the intake manifold to 30 foot-pounds. Torque the exhaust manifold bolts to 25 foot-pounds.Torque the flywheel bolts and the harmonic damper bolt to 60 foot-pounds.

Reported Performance Range

The 383 stroker varies in horsepower but seems to always produce a significant amount of torque. The GM HT383 Base Performance engine has 435 foot-pounds of torque at 4,000 rpm and boasts more than 400 foot-pounds of torque starting at 2,500 rpm. The GM ZZ383 Performance engine has 425 horsepower and 449 foot-pounds of torque. Other 383 stroker engines have been reported achieving 330 horsepower with 420 foot-pounds of torque, 395 horsepower with 410 foot-pounds of torque and 395 horsepower with 410 foot-pounds of torque.

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