25-28 combo

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Combo 25.

Combos 25-29 use World Products Sportsman II heads on a 355 cu. in. engine. Carburetor, intake, and cam are varied.

Combo 25 uses a 750 cfm carb, a Performer RPM intake, and a very conservative cam with 262° of duration. The combination makes 367 HP and 402 ft-lbs of torque.

 

Displacement:

355 cu. in.

Carburetor:

Edelbrock 750

Heads:

World Products Sportsman II

Intake:

Edelbrock Performer RPM

Camshaft:

Comp Cams Xtreme Energy 262° hydraulic, with 262/270° of duration, 218/224° of duration @ 0.050 in. lift, and 0.462/0.469 in. lift. (Corrected valve lift with 1.6:1 rockers is 0.493/0.500 in.)

Rockers:

Comp Cams Pro Magnum 1.6:1

Pistons:

Ross Racing flat tops

Rods:

Lunati 4340 steel

Crank:

cast

Distributor:

GM HEI with an MSD coil

Compression:

9.5:1

MAX HP:

367 @ 5600

MAX Torque:

402 @ 4100

Combo 26.

Combo 26 keeps all but one of the components from Combo 25—a healthier cam is used this time. The cam swap produces 49 more HP and only drops the torque 6 ft-lbs.

 

Displacement:

355 cu. in.

Carburetor:

Edelbrock 750

Heads:

World Products Sportsman II

Intake:

Edelbrock Performer RPM

Camshaft:

Comp Cams Xtreme Energy 274° hydraulic, with 274/286° of duration, 230/236° of duration @ 0.050 in. lift, and 0.487/0.490 in. lift. (Corrected valve lift with 1.6:1 rockers is 0.519/0.523 in.)

Rockers:

Comp Cams Pro Magnum 1.6:1

Pistons:

Ross Racing flat tops

Rods:

Lunati 4340 steel

Crank:

cast

Distributor:

GM HEI with an MSD coil

Compression:

9.5:1

MAX HP:

416 @ 5800

MAX Torque:

396 @ 4300

Combo 27.

Combo 27 goes back to the 262° camshaft, and a 600 cfm carb is used. This combination makes 356 HP and 384 ft-lbs of torque. Compared to Combo 25 (the same cam but a bigger carb), this combo produced 11 less HP and 18 less ft-lbs of torque.

 

Displacement:

355 cu. in.

Carburetor:

Edelbrock 600

Heads:

World Products Sportsman II

Intake:

Edelbrock Performer RPM

Camshaft:

Comp Cams Xtreme Energy 262° hydraulic, with 262/270° of duration, 218/224° of duration @ 0.050 in. lift, and 0.462/0.469 in. lift. (Corrected valve lift with 1.6:1 rockers is 0.493/0.500 in.)

Rockers:

Comp Cams Pro Magnum 1.6:1

Pistons:

Ross Racing flat tops

Rods:

Lunati 4340 steel

Crank:

cast

Distributor:

GM HEI with an MSD coil

Compression:

9.5:1

MAX HP:

356 @ 5600

MAX Torque:

384 @ 4100

Combo 28.

Combo 28 is almost identical to the previous combo, but the Performer RPM intake was exchanged for the Edelbrock Performer. Although the Performer is depicted as inferior to the RPM, this engine only produced 2 less HP and gained 1 ft-lb of torque. Perhaps the Performer RPM intake is not so superior to his little brother after all.

 

Displacement:

355 cu. in.

Carburetor:

Edelbrock 600

Heads:

World Products Sportsman II

Intake:

Edelbrock Performer

Camshaft:

Comp Cams Xtreme Energy 262° hydraulic, with 262/270° of duration, 218/224° of duration @ 0.050 in. lift, and 0.462/0.469 in. lift. (Corrected valve lift with 1.6:1 rockers is 0.493/0.500 in.)

Rockers:

Comp Cams Pro Magnum 1.6:1

Pistons:

Ross Racing flat tops

Rods:

Lunati 4340 steel

Crank:

cast

Distributor:

GM HEI with an MSD coil

Compression:

9.5:1

MAX HP:

354 @ 5600

MAX Torque:

385 @ 4100

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