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Combo 47.
Combos 47-52 come from pages 40-50 of the October 1990 Hot Rod Magazine. These six combos use a GM Goodwrench crate engine. The engine is first tested stock, and performance enhancements are done for each new combination.
Combo 47 is the stock run of the crate motor. The camshaft is low-performance, and the intake is cast-iron. With other stock components, this combo makes a meager 224 HP, but the engine produces a nice amount of torque (335 ft-lbs).
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| Displacement: |
350 cu. in. |
| Carburetor: |
1971 Quadrajet with #74 primary jets and a #45 metering rod |
| Heads: |
GM castings, with 78 cc combustion chambers, 1.94/1.50 in. valves, and a 2-angle valve job |
| Intake: |
1969 GM non-EGR cast iron |
| Camshaft: |
GM L69, with 192/202° of duration @ 0.050 in. lift, and 0.383/0.405 in. lift |
| Exhaust: |
stock cast-iron exhaust manifolds with 2 1/4 in. pipes and Thrush Turbo mufflers |
| Pistons: |
cast |
| Rods: |
stock |
| Crank: |
cast |
| Comp. Ratio: |
7.8:1 |
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| MAX HP: |
224 @ 4000 |
| MAX Torque: |
335 @ 3000 |
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Combo 48.
Combo 48 uses the same setup as Combo 47, except the exhaust manifolds are exchanged for some Hedman headers running through the same pipes and mufflers. This improves power by 18 HP and torque by 10 ft-lbs.
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| Displacement: |
350 cu. in. |
| Carburetor: |
1971 Quadrajet with #74 primary jets and a #45 metering rod |
| Heads: |
GM castings, with 78 cc combustion chambers, 1.94/1.50 in. valves, and a 2-angle valve job |
| Intake: |
1969 GM non-EGR cast iron |
| Camshaft: |
GM L69, with 192/202° of duration @ 0.050 in. lift, and 0.383/0.405 in. lift |
| Headers: |
Hedman 1 5/8 in. headers with 2 1/4 in. pipes and Thrush Turbo mufflers |
| Pistons: |
cast |
| Rods: |
stock |
| Crank: |
cast |
| Comp. Ratio: |
7.8:1 |
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| MAX HP: |
242 @ 4000 and 4250 |
| MAX Torque: |
345 @ 3000 |
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Combo 49.
Combo 49 improves upon Combo 48 by using a Holley 750 double pumper carb and Holley Contender intake. This results in 256 HP and 345 ft-lbs of torque.
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| Displacement: |
350 cu. in. |
| Carburetor: |
Holley 750 double pumper |
| Heads: |
GM castings, with 78 cc combustion chambers, 1.94/1.50 in. valves, and a 2-angle valve job |
| Intake: |
Holley Contender |
| Camshaft: |
GM L69, with 192/202° of duration @ 0.050 in. lift, and 0.383/0.405 in. lift |
| Headers: |
Hedman 1 5/8 in. headers with 2 1/4 in. pipes and Thrush Turbo mufflers |
| Pistons: |
cast |
| Rods: |
stock |
| Crank: |
cast |
| Comp. Ratio: |
7.8:1 |
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| MAX HP: |
256 @ 4250 |
| MAX Torque: |
345 @ 3250 |
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Combo 50.
A more aggressive camshaft is used in Combo 50. This is the only difference between Combo 50 and 49. The swap makes 17 more HP and 8 more ft-lbs of torque.
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| Displacement: |
350 cu. in. |
| Carburetor: |
Holley 750 double pumper |
| Heads: |
GM castings, with 78 cc combustion chambers, 1.94/1.50 in. valves, and a 2-angle valve job |
| Intake: |
Holley Contender |
| Camshaft: |
Crane hydraulic, with 204/216° of duration @ 0.050 in. lift, and 0.427/0.454 in. lift |
| Headers: |
Hedman 1 5/8 in. headers with 2 1/4 in. pipes and Thrush Turbo mufflers |
| Pistons: |
cast |
| Rods: |
stock |
| Crank: |
cast |
| Comp. Ratio: |
7.8:1 |
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| MAX HP: |
273 @ 4750 |
| MAX Torque: |
353 @ 3750 |
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Combo 51.
Combo 51 improves Combo 50 by using an even more aggressive cam. Although this cam is not wild by any means, it is quite a jump from the stock cam that was used in the beginning. Power is increased to 297 HP, and the torque goes up to 355 ft-lbs.
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| Displacement: |
350 cu. in. |
| Carburetor: |
Holley 750 double pumper |
| Heads: |
GM castings, with 78 cc combustion chambers, 1.94/1.50 in. valves, and a 2-angle valve job |
| Intake: |
Holley Contender |
| Camshaft: |
Crane hydraulic, with 216/228° of duration @ 0.050 in. lift, and 0.454/0.480 in. lift |
| Headers: |
Hedman 1 5/8 in. headers with 2 1/4 in. pipes and Thrush Turbo mufflers |
| Pistons: |
cast |
| Rods: |
stock |
| Crank: |
cast |
| Comp. Ratio: |
7.8:1 |
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| MAX HP: |
297 @ 5250 |
| MAX Torque: |
355 @ 3500 and 3750 |
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Combo 52.
Combo 52 is quite different than the previous five. Aluminum Corvette aluminum heads are used along with 1 3/4 in. headers. Since the Corvette heads have 58 cc combustion chambers, the compression ratio jumps from 7.8:1 to 9.9:1. The new heads produce 15 more HP and 14 more ft-lbs of torque.
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| Displacement: |
350 cu. in. |
| Carburetor: |
Holley 750 double pumper |
| Heads: |
Corvette aluminum, with 58 cc combustion chambers and 1.94/1.50 in. valves, (PN 10134336) |
| Intake: |
Holley Contender |
| Camshaft: |
Crane hydraulic, with 216/228° of duration @ 0.050 in. lift, and 0.454/0.480 in. lift |
| Headers: |
Hedman 1 3/4 in. headers with 2 1/4 in. pipes and Thrush Turbo mufflers |
| Pistons: |
cast |
| Rods: |
stock |
| Crank: |
cast |
| Comp. Ratio: |
9.9:1 |
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| MAX HP: |
312 @ 5250 and 5500 |
| MAX Torque: |
369 @ 3250 and 3500 |
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Combo 53.
Combos 53-54 come from pages 58-60 of the October 1990 Hot Rod Magazine. Back in 1990, these combos were two examples of the engines offered by American Speed. Both engines make some great power and torque.
Combo 53 uses rebuilt #993 GM heads with 2.02/1.60 in. valves. The camshaft is a healthy grind, with 234° of duration @ 0.050 in. of lift. This 355 cu. in. engine produces 421 HP and 438 ft-lbs of torque.
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| Displacement: |
355 cu. in. |
| Carburetor: |
750 Holley vacuum secondary |
| Heads: |
GM #993 castings, ported, with 2.02/1.60 in. valves and a 3-angle valve job |
| Intake: |
Edelbrock Victor Jr. and a 2 in. open-plenum spacer |
| Camshaft: |
Cam Dynamics 290, with 290° of duration, 234° of duration @ 0.050 in. lift, and 0.494 in. of lift |
| Headers: |
1 7/8 in. |
| Pistons: |
Speed-Pro forged flat tops |
| Rods: |
stock |
| Crank: |
cast |
| Comp. Ratio: |
9.0:1 to 10.0:1 |
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| MAX HP: |
421 @ 5300 |
| MAX Torque: |
438 @ 4700 |
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Combo 54.
Combo 54 uses a 383 cu. in. engine with rebuilt GM heads. Using 2.05/1.60 in. valves, this engine produces power over 500 HP. However, a very aggressive mechanical camshaft is used to make this power. Streetablity is a very questionable aspect of a cam with 316/323° of duration.
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| Displacement: |
383 cu. in. |
| Carburetor: |
750 Holley vacuum secondary |
| Heads: |
GM castings, ported, with 2.05/1.60 in. valves and a 3-angle valve job |
| Intake: |
Edelbrock Performer RPM and a 1 in. open-plenum spacer |
| Camshaft: |
GM #141 mechanical (PN 3927140), with 316/323° of duration, 256/268° of duration @ 0.050 in. lift, and 0.469/0.483 in. of lift |
| Rockers: |
Crane roller |
| Headers: |
1 7/8 in. |
| Pistons: |
Speed-Pro forged flat tops |
| Rods: |
stock |
| Crank: |
cast |
| Timing: |
36° |
| Comp. Ratio: |
10.0:1 |
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| MAX HP: |
510 @ 5600 |
| MAX Torque: |
481 @ 5300 |
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