In our last couple of installments (May and June issues), we tuned the Proform 950 carburetor (jets, spacer, air bleeds and air cleaner) and helped the heavy-breathing Dart 509 exhale more easily by changing to a high-flow Pypes mandrel-bent, 3-inch exhaust with an X-shaped crossover. These tuning mods added 38 hp and 38–lb-ft of torque to the wheels while maintaining a safe AFR (air/fuel mixture ratio) of 12.9 for the duration of the dyno pull (2,500 to 6,400rpm).
During the time spent on the dyno, we needed to be careful not to rev the Dart 509 Rat past 6,400 rpm (peak hp was at 6,000 rpm) because it would throw or twist the alternator belt. We tossed this belt when shifting at about 6,500 rpm on the Nova's maiden baseline pass (11.06 at 123mph). Before we could go back and strip test with our new-found power gains, we needed to solve the belt-throwing issue. For this, we ordered a set of March Performance underdrive pulleys and an alternator bracket.
The pulleys were changed in our home garage with simple hand tools and an impact wrench for the alternator pulley. After belt tension was set, we took the Nova for a reliability-check ride with enough shifts at over 6,500 rpm that we felt the rev-limiter working at 6,800. After the test drive, the new belts needed to have their tension readjusted--that thrill ride surely broke 'em in! Without anymore belt-throwing we felt ready to go back to the track--except we needed to ditch the 10-year-old, dry rotted and cracked rear tires for some fresh meats.
We revisited our friends at Shore Wheels, Tuckerton, New Jersey, for the mounting and balancing of a fresh set of Nitto drag radials. This is the good-guy shop that helped us handle the Total Cost Involved tubular front clip installation (February 2011 issue). Because the car is mini-tubbed, we had enough room for a set of Nitto's 325/50R15 NT555R-model drag radials. We would have liked to try its stickier NT01 drag radials, but so far they don't come in 15-inch, domestic-car sizes.
The previously mentioned dyno tested mods made the Nova feel like a monster on the ride to and from Atco Dragway (45 minutes each way) when compared to our initial baseline strip test. We were hoping to pick up 3-tenths from the power gains--as long as we could launch without tire spin. On the street the SS509 can easily smoke the tires at a 50mph roll--so getting it to hook wouldn't come easy. After an hour cool-down, we pulled up to Atco's sticky starting line. On the last yellow we cautiously rolled it out for a 1.60 60-foot and a 10.79 at 125.74 mph run. With a half hour cool-down we made a slightly more aggressive pass giving us a decent 1.53 60-foot (we feel 1.40s are possible with slicks) that yielded a 10.72 at 126 mph. We were happy to have picked up over 3-tenths.
After that good pass, we decided to make a back-up pass (hot-lap) with slightly faster throttle depression but spun to a 1.69 60-foot and a slowing 10.90 at 124.98. For our last lap, we produced another 1.53 60-foot, resulting in a 10.75 at 125.33 mph on the big end.
Stay tuned till next time, when we plan to install Competition Engineering's Slide-A-Link traction system with its three-way adjustable drag shocks to help us with our hook issues.