Baseline Start saving money for tires now. This thing is a torque monster. Components: Edelbrock RPM Air-Gap dual-plane; Holley 750 carb with 71 primary jets, 80 secondary jets; TTI 15/8-inch stepped headers; 34 degrees total timing; 155-degree water temperature; 160-degree oil temperature. RPM HP LB-FT 3,000 256 449 3,200 281 461 3,400 303 468 3,600 327 478 3,800 354 489 4,000 382 502 4,200 402 503 4,400 422 504 4,600 439 502 4,800 449 491 5,000 454 477 5,200 469 474 5,400 474 461 5,600 473 444 5,800 474 430 6,000 474 415 Test 1: Best Run Adding a 1-inch open spacer and jetting up the carburetor produced the best numbers we'd see out of this engine. Components: same as baseline plus a 1-inch open carb spacer and a jet change to 73/84. RPM HP LB-FT 3,000 255 446 3,200 276 453 3,400 294 455 3,600 321 469 3,800 354 489 4,000 383 504 4,200 409 512 4,400 432 517 4,600 450 514 4,800 461 505 5,000 467 490 5,200 479 484 5,400 485 471 5,600 483 453 5,800 478 433 6,000 472 413 Test 2 Next, we tried bigger headers but didn't gain any power. Components: same as Test 1 but substituting larger Hooker Super Competition 13/4-inch headers. RPM HP LB-FT 3,000 246 430 3,200 268 440 3,400 295 456 3,600 323 471 3,800 352 487 4,000 381 500 4,200 409 511 4,400 431 514 4,600 448 512 4,800 458 502 5,000 465 488 5,200 477 482 5,400 482 469 5,600 482 452 5,800 477 432 6,000 470 412 Hafliger said that though these are great heads for the money, with just a few inexpensive modifications, you can really ramp up the airflow and performance. He recommends cutting the spring pockets 0.100 inch to fit Comp beehive springs. Beehive springs are lighter, require a smaller, lighter retainer, and have lighter spring pressures versus a conventional spring, allowing more valve lift.Hafliger said that though these are great heads for the money, with just a few inexpensiv Next, he reground the intake valve seats to accept larger 2.02-inch valves and cut a four-angle valve job on the intake side, blending the valve job into the bowl slightly. The exhaust flowed well right out of the box, so Hafliger left the exhaust seat and port transition alone. He prefers 6000 Series Ferrea stainless steel valves. For optimum performance in the RHS heads, he back-cut the intake valves 30 degrees.Next, he reground the intake valve seats to accept larger 2.02-inch valves and cut a four- On the flow bench, these heads perform better than they look like they should. But to get an even more accurate idea of how the heads will flow on the engine, Hafliger also flowed the heads with the intake manifold installed. See the accompanying chart for all the numbers.On the flow bench, these heads perform better than they look like they should. But to get « | 1 | 2 | 3 | 4 | 5 | » | View Full Article By John McGann Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
