There comes a time when you may not just want more power, you may need more power. Times like when you are towing your show car or bass boat with that 1970s-and-earlier GM truck, and it just doesn't have the low-end grunt that you need to flatten hills or make a safe pass. For those times, our engineers designed the HT (high torque) 383 with lots of cubic inches and other components to enhance the low-rpm power that you need. The GM Performance Parts HT383 has been specifically engineered for low-rpm torque, and it's packed with durable parts that are all brand new.

Block Type: Cast iron with 4-bolt main caps
Bore x stroke (in): 4.00 x 3.80
Camshaft duration (@.050 in): 196 intake / 206 exhaust
Camshaft lift (in): .431 intake / .451 exhaust
Camshaft Part Number: 809-14097395
Camshaft type: Hydraulic roller
Compression ratio: 9.1:1
Connecting Rod Part Number: 809-12497624
Connecting rods Type: Heavy-duty PM steel
Crankshaft Part Number: 809-12489436
Crankshaft Type: Forged steel
Cylinder head Part Number: 809-12558060
Cylinder head Type: Vortec iron; 64cc chambers
Displacement (cu in): 383
Engine Name: HT383
Engine type: Chevy small-block V-8
Ignition timing: 32 total @ 4000 rpm with vacuum advance disconnected
Maximum rpm: 5000
Piston Part Number: 12499103
Pistons Type: Hypereutectic aluminum
Recommended fuel: 87 octane
Rocker arm ratio: 1.5:1
Rocker arms Part Number: 10089648
Rocker arms Type: Stamped steel
Valve size (in): 1.94 intake / 1.50 exhaust
Water Pump Part Number: 88894341
Water pump Type: Cast iron