Superior Automotive Holley Carburetor Dyno Testing - Fueling Around
 Here are the results of the best baseline pull. Our Windsor uses the stock crank and displacement. So with 274.83 hp at 5,100 rpm and a torque reading of 311.99 lb-ft at 3,700 rpm, these numbers are pretty respectable for a street-driven daily driver. The graph contains the same information as the numerical tables, however, certain parts (such as the substantial dip in both horsepower and torque at 4,350 rpm) become more evident on a graph. | RPM | HP | TQ | | 2,800 | 144.91 | 271.80 | | 2,900 | 155.99 | 284.30 | | 3,000 | 166.82 | 292.05 | | 3,100 | 175.73 | 299.41 | | 3,200 | 185.15 | 305.52 | | 3,300 | 193.20 | 307.48 | | 3,400 | 200.70 | 310.03 | | 3,500 | 206.77 | 310.28 | | 3,600 | 218.60 | 311.63 | | 3,700 | 219.79 | 311.99 | | 3,800 | 226.26 | 311.34 | | 3,900 | 229.64 | 309.26 | | 4,000 | 234.82 | 308.33 | | 4,100 | 233.51 | 305.53 | | 4,200 | 243.28 | 304.23 | | 4,300 | 247.18 | 301.92 | | 4,400 | 250.03 | 298.44 | | 4,500 | 254.66 | 297.22 | | 4,600 | 254.66 | 290.76 | | 4,700 | 257.52 | 287.77 | | 4,800 | 260.79 | 285.36 | | 4,900 | 263.35 | 287.53 | | 5,000 | 272.18 | 285.90 | | 5,100 | 274.83 | 283.03 |
Work begins on the metering block, which has been placed in a spotless aluminum tray. The other Holley carb shown here (foreground) was also scheduled for rebuilding and tuning that day. | 
New jet sizes are part of the carburetor hop-up. Passageways going to the power valve are also enlarged. The size of the replacement power valve is part of the secret recipe. | 
All the care in the world doesn't mean anything if the reassembled carburetor leaks. Even on a relatively new carb like this one, the gasket material needs a little gentle persuasion with a fine-wire brush to create a clean surface for the new gaskets. Similar modifications were performed on the forward metering block; the carb was then reassembled on the engine. |
| RPM | HP | TQ | | 2,800 | 152.30 | 285.69 | | 2,900 | 163.15 | 295.48 | | 3,000 | 170.56 | 298.60 | | 3,100 | 181.43 | 307.38 | | 3,200 | 189.66 | 311.28 | | 3,300 | 193.06 | 317.81 | | 3,400 | 205.74 | 317.81 | | 3,500 | 212.66 | 319.12 | | 3,600 | 220.02 | 320.99 | | 3,700 | 227.33 | 322.69 | | 3,800 | 232.87 | 321.86 | | 3,900 | 237.50 | 319.85 | | 4,000 | 243.43 | 319.62 | | 4,100 | 245.84 | 315.57 | | 4,200 | 250.25 | 312.93 | | 4,300 | 255.85 | 312.50 | | 4,400 | 259.06 | 309.23 | | 4,500 | 259.18 | 302.50 | | 4,600 | 264.33 | 301.81 | | 4,700 | 263.62 | 300.18 | | 4,800 | 275.27 | 301.20 | | 4,900 | 277.63 | 297.58 | | 5,000 | 283.13 | 297.41 | | 5,100 | 287.16 | 295.72 | | 5,200 | 289.48 | 292.38 |
Spaccarotella does a final walkaround and safety check before firing up the Mustang. Not shown in the photo is an even larger fan to ensure adequate engine cooling. | 
After two pulls, it is clear that a few more small adjustments are needed. The engine stumbled when the throttle was nailed, so Spaccarotella increased the volume of the primary accelerator pump shot as well as the volume for the rear pump. | 
As a final step before testing, Spaccarotella enlarges the air-bleed passageways by an unknown amount. The exact balance of the modifications he does is the secret to success. When Superior Automotive rebuilds your Holley carb, you get every trick in its proven book. Once the Mustang was run on the rollers, it didn't take long to notice a worthwhile gain. |
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