For a third time-without shutting the Hemi down-it was pulled back around, and the reaction time of .581 and a 60-foot time of 1.96 netted us an 11.61 at 124.6 mph. It was almost a carbon copy of the run before, but this time, we headed for the pits to let the Hemi cool down a bit.
The rear tire pressure, which we should have checked before the first pass, showed 24 pounds on the passenger side and 26 pounds on the driver side. In previous testing, 34 pounds was the magic number in the Challenger, so that's what we used.
A check of the ignition timing showed we were running 34 degrees total advance, and we left it there for the time being. To see how the Hemi would react, we loosened the valve lash to .016, at operating temp, and after a 40-minute cool-down, we hit the track again.
This time, we were rewarded with an 11.45 at 124.92-the car's best ever quarter-mile pass. It had a 1.89 60-foot time and minimal tire spin, which, for the most part, occurred in Second gear. The car seemed to like the changes we made, and a quick, hot lap back to the staging lanes rewarded us with a 60-foot time of 1.90 and a final e.t. of 11.41 at 124.89 mph.
During this second hot lap, the Hemi was shifted at 6,300 rpm. The next 18 or so passes involved three more valve-lash adjustments. We started by setting the lash at .012 intake and .020 exhaust, and then .020 intake and .012 exhaust, followed by .020 on both intake and exhaust. All e.t.'s, except for a few passes where we lost traction, were in the 11.40-11.50-e.t. range. During this time, our 60-foots ranged from 2.04-1.90. It appeared the lash setting did not affect the engine. Maybe the dyno would have been a better place to test valve lash.
On what was starting to become a long day, we made one final lash adjustment to .012 intake and .016 exhaust. We contrived this setting based on the data we had, thinking it would be a good place to settle. We cranked up the timing to 36 degrees and took a late lunch. After the longest cool-down of the day-almost an hour-it was getting late, and we only had time for a couple more passes.
The temperature had dropped closer to 50 degrees when we staged the Hemi. Launching the car with a .601 reaction time put out a 60-foot time at 1.87. The car launched hard, and Second gear had minimal tire spin. At the 330-foot mark, the Hemi posted an impressive 5.000 e.t. Everything came together, and the Challenger posted what we believe is the fastest e.t. ever from a Stock Appearing class car. When the lights lit up at the big end, the Challenger posted an 11.37 e.t. at an astounding 125.88 mph. All testing was done as the car raced, including the use of repop Polyglas tires.
Just imagine what this Hemi would be capable of with a free-flowing exhaust and aftermarket intake and carb! But that's the fun of racing in the Stock Appearing class.