$6400

P/N 12568778
  This new 502ci, H.O. engine is identical to the earlier version P/N 10185085 except it has a steel cam with roller lifters. This high-torque engine offers exceptional performance and value in an over-the-counter package for off-highway applications. During development of the H.O. 502 assembly, a test engine equipped with a 750cfm Holley four-barrel carburetor, aftermarket headers (2” x 30” primaries) and low-restriction mufflers produced 450 horsepower at 5250 rpm and 550 lb-ft torque at 3500 rpm.
 Starting with a GEN VI four bolt main block, we fill it with forged pistons, forged 4340 steel connecting rods with 7/16” bolts,a 1053 forged steel crankshaft, and a steel roller camshaft. Then we torque down a pair of big breathing rectangular port heads with 2.19” intake and 1.88” exhaust valves. With their 118cc combustion chambers yielding a streetable 8.75:1 compression ratio, this engine is ready to rock on readily available premium gas.
High Output 502 engines are completely assembled (less ignition, spark plug wires, carburetor, and exhaust manifolds) using brand new, premium quality components. The H.O. 502 assembly includes an aluminum dual plane intake manifold, cast iron water pump, 8” damper, 6 quart oil pan with windage tray, and a 14” automatic transmission flexplate. All H.O. engines are fire - tested and final balanced at the factory to ensure their quality and performance. All you need now are carb, HEI ignition system, headers with 2” x 30” primaries, low restriction mufflers, and a vehicle with sticky tires.     

The 502 HO is not intended for marine use, and should only be used in 1976 and earlier Pre-emissions street vehicles or any year off road vehicles. However it can be upgraded for marine use with brass freeze plugs and stainless steel head gaskets and the decission in what to install it is your respondsibilty.

Further more the 502 has a reputation for burning oil due to cylinder distortion from the head bolts, and poor oil rings. A minimal upgrade of better rings is strongly recommended, and preferably boring the motor to 509 and raising the compression to 9:1 is useful. We can also add a slightly larger roller camshaft.

Install new rings $350
Honing with a Torque plate add $100
KB Hypereutectic 9:1 or 10:1 Pistons add $350
Mahle 9:1 Light Weight Forged Pistons add $500.
Balancing and Installing  Pistons on Rods add $200
New Roller Camshaft $150
      226/226 545/540 115 1800-5600rpm or
      236/232 576/588 114 2200-6000rpm
CompCams Roller Camshafts add $260

Block: The H.O. 502 is based on the Gen VI cast iron short-deck marine block with 4.466” diameter siamesed cylinder bores, four-bolt main bearing caps, and blind-tapped head bolts. Like all Gen VI big-block V8s, 502 has a leak-resistant one-piece rear crankshaft seal, relocated oil passages, and a redesigned oil filter pad with integral oil cooler connections. It has no mechanical fuel pump boss, so it requires an electric fuel pump.
Crankshaft Assembly: A 4.00” stroke forged 1053 steel crankshaft is the heart of the H.O. 502 engine. The crank assembly also includes forged 4340 steel connecting rods with 7/16” bolts and forged aluminum pistons with a nominal compression ratio of 8.75:1.
Induction System: The H.O. 502 is equipped with a high-rise aluminum four-barrel intake manifold and rectangular port cylinder heads. These cast iron heads have open-style 188cc combustion chambers and 2.19/1.88” diameter valves.
Rocker Covers: The H.O. 502’s rigid cast aluminum covers and screw-in oil filler cap resist oil leaks.
Valvetrain: The H.O. engine’s new hydraulic roller tappet camshaft (#24502611) has .511/.540” valve lift and 211/230 degrees duration (at .050” tappet lift). The H.O. engine uses a non-adjustable “net lash” roller tappet valvetrain and 3/8” diameter pushrods.
Technical Notes: The 502ci engine assembly includes a 14” diameter automatic transmission flexplate with dual bolt patterns (#10185034). For manual transmission applications, a 14” diameter flywheel drilled for an 11” clutch is available as #14096987. Due to differences in crankshaft counterweights, this flywheel should be used only with the forged steel crankshafts installed in H.O. 454 and H.O. 502 engine assemblies.
     The H.O. 502 engine assembly includes a six quart oil pan. When installing a Gen V or VI big-block in most Chevelles, Camaros, or similar chassis, the pan and oil pump must be modified to clear the front crossmember or use 4 quart oil pan kit P/N 12495360.