Big-Block Chevy Crate Engine - Back To The Street, Part 1

Time for the first dyno pull. All of our pulls were made from 4,100 rpm up through 5,900 rpm. With 6 quarts of break-in oil, and timing set at 24-degrees, we made 405 hp and 460 lb-ft of torque. A little on the low side, but as we started tuning and adding timing, we suspected we would see some more power. After two more pulls and virtually no improvement, we figured something was wrong.

Finally...the moment of truth. There are few experiences more nerve-racking than starting a motor for the first time, but we knew we would have no problems with the GM Performance Parts ZZ454/440. Bob turned on the ignition and the fuel pumps, and the big-block immediately came to life. Oil pressure was steady at 75 psi, water temperature was steadily rising, and she idled nicely at around 1,600 rpm, as we made sure to break the 454 in properly.

Dave Jack, of Dave Jack Cylinder Heads, handed us a 950-cfm carburetor that he had heavily modified, and uses often when customers are having issues on the dyno. What could it make, 15 hp more?

We made one pull and as the motor was rising through the rpm range, we all looked at each other and knew we made some power. The engine sounded much more clean and crisp, equating to some serious horsepower numbers. We saw 491 hp and 517 lb-ft of torque- a whopping 86 hp and 58 lbs of torque over our initial tests.

We started fiddling with the 770 Holley we originally slapped on the motor. We emptied the fuel, cleaned it out, opened and closed the secondaries, and bolted it on for another try. It turns out that the secondaries were caught-up on a linkage and once we got the problem fixed, the motor ran through the rpm like a dream. How does 491 hp and 521 lb-ft of torque sound? A lot better than the 440 GMPP rates it!

Allowing for better airflow and increased volume, a carb spacer is almost guaranteed to make a few horsepower ... if you can fit it under the hood. We stole this 1 1/2-inch spacer from Dave. it should clear under our Camaro's L88-style hood, no sweat.

Last but not least, we let the motor sit for about 20 minutes, slapped on a 1 1/2-inch carb spacer, and pushed the wand to WOT. What a great way to end the day. With the 770-cfm Holley right out of the box, 93-octane fuel, 34 degrees of timing, and the air/fuel ratio averaging 12.8, we could not have been happier with the result: 502 hp, 547 tq.