Let’s not quibble: Engine dynamometers weren’t taxed
very hard in the 1970s. So, if a lack of horsepower is all
that’s keeping you from enjoying your 1970s-and-earlier
GM truck, the HT383 is your ticket to ride—or tow.
Designed for trucks and trailer towing, the HT383 is
assembled with all new components to produce a
383-cubic-inch "stroker" small-block engine. It produces
435 lb.-ft. of torque at 4000 rpm, but more importantly, it
produces more than 400 lb.-ft. 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.
A specially modified engine block and 3.80-inch-stroke
crankshaft enable the HT383’s displacement, and the
reciprocating assembly is comprised of heavy-duty
components that will help provide years of durable
performance.
The brand-new HT383 makes a great alternative to salvage
and rebuilt engines. You’ll be satisfied after your truck and
trailer flattens that first mountain!

• TECH SPECS: HT383
• Part Number: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12499101
• Engine type: . . . . . . . . . . . . . . . . . . . . . . . Chevy small-block V-8
• Displacement (cu in): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
• Bore x stroke (in) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.00 x 3.80
• Block: . . . . . . . . . . . . . . . . . . . . cast iron with 4-bolt main caps
• Crankshaft: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . forged steel
• Connecting rods: . . . . . . . . . . . . . . . . . . . . heavy-duty PM steel
• Pistons: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cast aluminum
• Camshaft type: . . . . . . . . . . . . . . . . . . . . . . . . . . hydraulic roller
• Camshaft lift (in): . . . . . . . . . . . . . . . . .431 intake / .451 exhaust
• Camshaft duration (@.050 in) . . . . . 196° intake / 206° exhaust
• Cylinder heads: . . . . . . . . . . . . GM Vortec iron; 64cc chambers
• Valve size (in): . . . . . . . . . . . . . . . . . . 1.94 intake / 1.50 exhaust
• Compression ratio: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1:1
• Rocker arms: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . stamped steel
• Rocker arm ratio: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5:1
• Water pump: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . cast iron
• Recommended fuel: . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 octane
• Ignition timing: . . . . . . . . . . 32° total @ 4000 rpm with vacuum
• advance disconnected
• Maximum rpm: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5000

INSTALLATION NOTES
• Requires addition of carburetor, ignition and starter (not included).
• Rochester Quadrajet or Holley 750-cfm carburetor recommended.
• Comes with 12.75-inch automatic transmission flexplate.
Requires externally balanced flywheel for manual transmission.
See chart on page 80.
• Has right-side oil dipstick.
• Intended for 1979-and-earlier pre-emissions street vehicles and
all off-road vehicles.