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Combo 1.
Combos 1-3 came from the World Products web site. Although only cam duration numbers are given, all of the three different duration numbers happen to be the exact durations of the three most popular Comp Cams Xtreme Energy camshafts.
Combo 1 is a basic engine build with the popular Sportsman II heads and a conservative camshaft. Although torque numbers are not given, the short-duration cam probably helps to produce more than 350 ft-lbs of torque. |
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Displacement: |
350 cu. in. |
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Carburetor: |
modified 600 cfm |
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Heads: |
World Products Sportsman II |
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Intake: |
Dart II Sportsman dual plane |
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Camshaft: |
262° hydraulic, (probably the Comp Cams Xtreme Energy 262°, with 262/270° of duration, 218/224° of duration @ 0.050 in. of lift, and 0.462/0.469 in. of lift.) |
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Comp. Ratio: |
9.2:1 |
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MAX HP: |
350 @ 5500 |
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Combo 2.
Combo 2 has a little more compression, which could account for a little bit of power gain, but the cam with longer duration is what really raises the power. I am sure that the torque does not increase too much, and it may actually decrease. The carb upgrade might have added power, but the 600 cfm carb could have easily produced this much power. |
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Displacement: |
350 cu. in. |
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Carburetor: |
modified 750 cfm |
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Heads: |
World Products Sportsman II |
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Intake: |
Dart II Sportsman dual plane |
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Camshaft: |
268° hydraulic, (probably the Comp Cams Xtreme Energy 268°, with 268/280° of duration, 224/230° of duration @ 0.050 in. of lift, and 0.477/0.480 in. of lift.) |
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Comp. Ratio: |
9.5:1 |
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MAX HP: |
375 @ 6000 |
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Combo 3.
Combo 3 has even more compression than the previous combos, which probably adds some power. The combustion chambers are cleaned up some, and an even more aggressive cam is used on this engine. If the camshaft is the Xtreme Energy grind, the torque is beginning to have some trouble with this amount of duration. |
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Displacement: |
350 cu. in. |
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Carburetor: |
modified 750 cfm |
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Heads: |
World Products Sportsman II, bowl blended |
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Intake: |
Dart II Sportsman dual plane |
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Camshaft: |
274° hydraulic, (probably the Comp Cams Xtreme Energy 274°, with 274/286° of duration, 230/236° of duration @ 0.050 in. of lift, and 0.487/0.490 in. of lift.) |
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Comp. Ratio: |
9.8:1 |
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MAX HP: |
430 @ 6000 |
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Combo 4.
Combos 4-7 comes from page 39 of the February 1989 issue of Hot Rod Magazine. All four combos use the 383 cu. in. engine with rebuilt GM heads and Holley 750 double pumper. These combos show the difference between some intakes and heads.
Combo 4 uses an Edelbrock Performer intake and a 280° cam. The power and torque numbers are pretty good. |
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Displacement: |
383 cu. in. |
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Carburetor: |
Holley 750 double pumper |
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Heads: |
GM #441 castings, 76cc chambers, 2.02/1.60 in. valves, pocket ported |
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Intake: |
Edelbrock Performer |
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Camshaft: |
Comp Cams 280° Magnum hydraulic, with 280/280° of duration, 230/230° of duration @ 0.050 in. lift, and 0.480/0.480 in. lift |
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Rockers: |
1.5:1 |
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Headers: |
1 5/8 in. street |
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Pistons: |
TRW forged |
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Rods: |
5.565 in. |
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Crank: |
cast |
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Comp. Ratio: |
9.3:1 |
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MAX HP: |
382 @ 5300 |
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MAX Torque: |
400 @ 4500 |
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Combo 5.
Combo 5 keeps the Performer intake from Combo 4, but a 292° cam is used. This camshaft duration increase drives the power up 17 HP, and the torque stays about the same. It is suprising that a cam with this much duration does not drop the torque level. |
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Displacement: |
383 cu. in. |
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Carburetor: |
Holley 750 double pumper |
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Heads: |
GM #441 castings, 76cc chambers, 2.02/1.60 in. valves, pocket ported |
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Intake: |
Edelbrock Performer |
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Camshaft: |
Comp Cams 292° Magnum hydraulic, with 292/292° of duration, 244/244° of duration @ 0.050 in. lift, and 0.501/0.501 in. lift |
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Rockers: |
1.5:1 |
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Headers: |
1 5/8 in. street |
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Pistons: |
TRW forged |
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Rods: |
5.565 in. |
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Crank: |
cast |
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Comp. Ratio: |
9.3:1 |
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MAX HP: |
399 @ 5700 |
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MAX Torque: |
399 @ 5000 and 5500 |
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Combo 6.
Combo 6 goes back to the 280° camshaft, but an Edelbrock Victor Jr. intake is used instead. This combination produces 17 more HP and a little more torque. Even though the Victor Jr. intake has been billed a high-RPM-only intake, this comparison shows that the intake produced more low-end torque than the Performer. Victor Jr.'s are becoming popular intakes as more car guys realize just how streetable they are. |
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Displacement: |
383 cu. in. |
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Carburetor: |
Holley 750 double pumper |
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Heads: |
GM #441 castings, 76cc chambers, 2.02/1.60 in. valves, pocket ported |
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Intake: |
Edelbrock Victor Jr. |
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Camshaft: |
Comp Cams 280° Magnum hydraulic, with 280/280° of duration, 230/230° of duration @ 0.050 in. lift,and 0.480/0.480 in. lift |
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Rockers: |
1.5:1 |
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Headers: |
1 5/8 in. street |
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Pistons: |
TRW forged |
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Rods: |
5.565 in. |
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Crank: |
cast |
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Comp. Ratio: |
9.3:1 |
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MAX HP: |
400 @ 5700 |
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MAX Torque: |
403 @ 4500 and 5000 |
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