Torque flattens out hills when you’re towing, and nothing
flattens hills like 502 cubic inches of big-block! GMPP’s
HT 502 engine has all the same great performance characteristics
of our other 502 engines, but this one is
designed specifically for 1979-and-older trucks.
The HT502 is filled with a 4.00-inch forged crankshaft,
4.47-inch forged aluminum pistons, forged rods and a
roller camshaft. The deep-breathing iron cylinder heads,
with their mid-size valves and oval ports, deliver
maximum cylinder fill at low rpm, providing excellent
low-rpm efficiency, power and torque.
GMPP delivers the engine complete with an oil pan,
valvetrain, valve covers, timing set and balancer. You
add an intake manifold, carburetor, water pump, starter
and ignition system. In fact, all necessary parts can be
purchased from your GMPP dealer.
With the HT502, your revitalized truck will climb those
hills without breaking a sweat!

• TECH SPECS: HT502
• Part Number: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88890534
• Engine type: . . . . . . . . . . . . . . . . . . . . . . . . . Chevy big-block V-8
• Displacement (cu in): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 502
• Bore x stroke (in): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.47 x 4.00
• Block: . . . . . . . . . . . . . . . . . . . . cast iron with 4-bolt main caps
• Crankshaft: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . forged steel
• Connecting rods: . . . . . . . . . . . . . . . . forged steel, shot peened
• Pistons: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . forged aluminum
• Camshaft type: . . . . . . . . . . . . . . . . . . . . . . . . . . . hydraulic roller
• Camshaft lift (in): . . . . . . . . . . . . . . . . . .480 intake / .483 exhaust
• Camshaft duration (@.050 in) . . . . . . 204° intake / 209° exhaust
• Cylinder heads: . . . . . . . . . . . . iron round port; 118cc chambers
• Valve size (in): . . . . . . . . . . . . . . . . . . . 2.07 intake / 1.73 exhaust
• Compression ratio: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.75:1
• Rocker arms: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . stamped steel
• Rocker arm ratio: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7:1
• Flexplate: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-inch
• Recommended fuel: . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 octane
• Ignition timing: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4° BTDC
• Maximum rpm: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5500

INSTALLATION NOTES
• Designed for 1979-and-older and pre-emissions street vehicles,
or any off-road vehicle.
• Requires the addition of carburetor, water pump, starter,
distributor and ignition system.
• Clutch linkage boss is cast into block, but must be drilled and
tapped. When using cast iron exhaust manifolds, lower head
bolts may need to be replaced with bolts with shorter heads,
for clearance.
• Requires electric fuel pump because the Gen VI block has no
mechanical pump boss.
• Comes with an externally balanced 14-inch automatic
transmission flexplate; use externally balanced flywheel P/N
14096987 and 11-inch clutch assembly for manual transmission.
•Not intended for electronic fuel injection because heavy loads
and/or high altitude condition could cause lean fuel mixture.
• Not intended for marine applications.