After building the 490 stroker, it was bolted up to the Muscle Motors engine dyno to tune and test it. Once the engine was fired up and brought to temperature (170 degrees), Mike initiated his first pull from 2,500 to 5,200 rpm with the timing at 31 degrees, and the carburetor jetted with No. 83 primary jets and No. 84 secondary jets. This pull basically helped seat the rings and made sure everything was operating properly. On the second pull, there were no tuning changes made but Mike decided to pull the engine from 2,800 to 5,200 rpm to clean up the air/fuel readings. This pull netted 517 hp at 5,000 rpm and an incredible 612 lb/ft of torque at 3,900 rpm. Checking a plug, Mike noticed the engine was a little rich, so he bumped the ignition timing to 33 degrees, netting 526 hp and 616 lb/ft of torque. Further power tuning included bumping the timing to 36 degrees, and leaning the carb slightly with jet and air-bleed changes. The net result was 534 hp at 5,200 rpm and 619 lb/ft of torque at 3,900 rpm. Not bad for an engine running on 92 octane pump fuel purchased at the local station!
After tuning for power, Mike wanted to tune the big-block for economy. A series of pulls was again initiated and jetting changed to the lean side, working to 80s in the primary, and 88s in the secondaries for proper air/fuel ratios. Though this was an economy tune, the engine actually made its best pull of all in this configuration, netting 537 hp at 5,300 rpm and 628 lb/ft of torque at 3,900 rpm. The gain in horsepower was likely a combination of tuning, the rings fully seating, and the engine loosening slightly as the internals established wear patterns. Feeling the engine was properly tuned and ready to run, Mike deemed it healthy and prepped it to ship. Be sure you're at Carlisle's All-Chrysler Nationals this year, and this potent 383 stroker may just end up in the engine bay of one of your cars!