Cummins Engine Swap Kits

CMW Trucks - 1947 - 1972 Chevy Truck Parts


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HT383 - A big-inch small-block tuned for torque!

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. It produces 435 lb.-ft. of torque at 4000 rpm, but more importantly, it produces more than 400 lb.-ft. of weight-moving torque from 2500 rpm all the way up to its 4000 rpm peak. In other words, your trailer’s worth of weekend fun is barely noticeable when hooked to a vehicle equipped with the HT383.

The bottom end has a 383 stroker forged steel crankshaft, heavy-duty rods, and hypereutectic pistons. The block is cast iron with 4-bolt main caps, and it’s up to the task of making lots of power for years to come.

The brand new HT383 makes a great alternative to salvage and rebuilt engines. Once installed, the HT383 makes it possible to look forward to that big hill or long haul. Don’t just drive to your favorite fishing hole—be the first one there!

Possible Applications

  • Your hot rod truck
  • Your hot rod station wagon
  • Your heavy project car
  • Anything that requires big-block torque in a small-block package

*Applications have not been validated. They are merely suggestions of how you might enjoy your GM Performance Parts crate engine. Some applications may affect engine warranty. See specific warranty information. Some applications may not be emission legal; check state and local ordinances.

Part Number: 12499101
Engine type: Chevy small-block V-8
Displacement (cu in): 383
Bore x stroke (in): 4.00 x 3.80
Block (P/N 88962516): Cast iron with 4-bolt main caps
Crankshaft (P/N 12489436): Forged steel
Connecting rods (P/N 12497624): Heavy-duty PM steel
Pistons (P/N 12499103): Hypereutectic aluminum
Camshaft type (P/N 14097395): Hydraulic roller
Camshaft lift (in): .431 intake / .451 exhaust
Camshaft duration (@.050 in): 196'c1 intake / 206'c1 exhaust
Cylinder heads (P/N 12558060): Vortec iron; 64cc chambers
Valve size (in): 1.94 intake / 1.50 exhaust
Compression ratio: 9.1:1
Rocker Arms (P/N 10089648): Stamped steel
Rocker arm ratio: 1.5:1
Water pump (P/N 88894341): Cast iron
Recommended fuel: 87 octane
Ignition timing: 32'c1 total @ 4000 rpm with vacuum advance disconnected
Maximum rpm: 5000

Chevy Performance ht 383 engine image

Part #:12499101

ht 383 dyno image

Installation Notes

  • NOTE: Distributor with melonized steel gear MUST be used with long blocks and partial engines with steel camshafts, or engine damage will occur. We recommend HEI distributor P/N 93448806.
  • Requires addition of carburetor, ignition and starter (not included).
  • Rochester Quadrajet or Holley 750-cfm carburetor recommended.
  • Comes with 12.75" automatic transmission flexplate. Requires externally balanced flywheel for manual transmission.
  • Has right-side oil dipstick.
  • Intended for pre-1977 street vehicles and all off-road vehicles.