Pulley Swap - What a Drag Part 6 - Super Chevy Magazine

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.

1 After throwing, snapping and twisting alternator belts one too many times, we ordered a set of March Performance underdrive pulleys (PN 7020) to cure the issue. We stayed with the old-school V-groove type instead of switching to a set of serpentine pulleys like most people seem to be doing these days. Be sure to read, understand and follow the provided instructions before installation.
1 After throwing, snapping and twisting alternator belts one too many times, we ordered a
2 For perfect belt alignment, we utilized a March Performance alternator bracket kit (PN 20125). The high quality March pulleys and the lower bracket are CNC-machined from 6061-T6 billet aluminum for a perfect fit (they come powdercoated, too). To get proper belt tension, the high strength stainless steel tensioning rod (turnbuckle) with chrome moly rod ends is stronger and better looking than the stock-type, stamped-steel upper bracket it replaces.
2 For perfect belt alignment, we utilized a March Performance alternator bracket kit (PN
3 Here's looking at the stock steel pulleys and alternator bracket setup we'll be glad to get rid of. This was what was on the car when we purchased it. Notice the diameter of the pulleys is different to drive each belt for the alternator and the power steering pump. The large diameter crank pulley made for excessive belt speed with the small diameter alternator pulley that causing it to throw the belt at high rpm. The stock alternator bracket and spacer contributed to the alternator belt alignment being slightly off center.
3 Here's looking at the stock steel pulleys and alternator bracket setup we'll be glad to

4a Be sure to match the crank pulley V-groove alignment by checking on a flat surface before placing it on the engine. The precision-machined March aluminum pulley is 5 inches in diameter with two V-grooves and is lighter to help the engine rev faster.
4a Be sure to match the crank pulley V-groove alignment by checking on a flat surface bef
4b The stock stamped-steel crank pulley has two 6-inch (power steering, smog pump?) and one 7-inch (alternator) diameter V-grooves. We placed the new pulley on top of the old pulley (end to end) to check bolt-hole alignment.
4b The stock stamped-steel crank pulley has two 6-inch (power steering, smog pump?) and o
5 To assure the water pump pulleys match for correct alignment, we placed them on equal height beverage cans. The V-grooves on ours matched perfectly. If alignment is off more than a 1/8-inch, water pump spacers are available from a March Performance dealer.
5 To assure the water pump pulleys match for correct alignment, we placed them on equal h

6 The 25-percent underdrive crank pulley bolted up perfectly to the ATI Super Damper. Now at 6,000 rpm the alternator, water pump, power steering pump and cooling fan will be running at the equivalent of only 4,500 rpm. This will add life to those components and allow the coolant more time in the radiator to cool the engine as well, if not better, than before pulley installation.
6 The 25-percent underdrive crank pulley bolted up perfectly to the ATI Super Damper. Now
7 We placed the water pump pulley on the snout of the water pump to check alignment with the crank pulley. It appears to be perfect.
7 We placed the water pump pulley on the snout of the water pump to check alignment with
8a Off came the ugly lower alternator bracket, spacer and bolts for the new, stronger and more aesthetically-pleasing billet aluminum bracket, spacer and bolts.
8a Off came the ugly lower alternator bracket, spacer and bolts for the new, stronger and

8b March did its homework to provide correct alternator alignment which prevents twisting, throwing or snapping belts--we'd had enough of that!
8b March did its homework to provide correct alternator alignment which prevents twisting
9 The old and the new alternator pulley were placed along side of each other on a flat surface to be sure their V-groove lined up evenly. The aluminum March pulley felt noticeably lighter than the steel pulley and it was a 1/2-inch larger in diameter. Also, the V-groove was slightly deeper for better belt retention.
9 The old and the new alternator pulley were placed along side of each other on a flat su
10 An impact wrench was used to easily loosen and tighten the nut that holds the alternator pulley in place. The old pulley was pulled off and the new pulley was easily put in place by hand.
10 An impact wrench was used to easily loosen and tighten the nut that holds the alternat

11a The March kit includes this cool-looking bullet nose we installed on the face of the alternator pulley.
11a The March kit includes this cool-looking bullet nose we installed on the face of the
11b When we trial-fitted the alternator, we suspected we would run into an interference issue with the radiator shroud. Without a decent tin snip handy at home we couldn't notch the shroud for clearance.
11b When we trial-fitted the alternator, we suspected we would run into an interference i
12a We ran into another clearance issue because the alternator fan was 1/2-inch-larger in diameter than usual. This caused the fan blades to hit the lower bracket even when the upper tensioning rod was adjusted all the way out.
12a We ran into another clearance issue because the alternator fan was 1/2-inch-larger in

12b Down the road we'll change to a regular diameter alternator fan so we can use the stainless steel tensioning rod (turnbuckle) with its chrome moly rod ends. For now we just used the stock-type chromed upper bracket to provide the additional adjustment needed to clear the fan away from the lower bracket.
12b Down the road we'll change to a regular diameter alternator fan so we can use the sta
13 To measure for new belts, we cut the old belts. The power steering pump and the alternator were placed where there would be room for proper clearance and belt tension adjustment. The belt was installed in position taught where the two ends overlap. Either mark or write down that measurement. As seen, we needed an alternator belt roughly 2 inches shorter. We went to the local parts jobber for new Gates belts in the needed length.
13 To measure for new belts, we cut the old belts. The power steering pump and the altern
14 The belts lined up perfectly with the precision-engineered lower alternator bracket, spacer and pulleys. This handsome underdriven pulley set will help prevent the belts from being thrown off by reducing the speed in which the belts travel. We've been using March's underdrive pulleys for over 20 years with great success and have never thrown, twisted or snapped a belt.
14 The belts lined up perfectly with the precision-engineered lower alternator bracket, s

15a In this comparison shot, you can see how the belt goes further into the slightly deeper V-groove for better belt retention.
15a In this comparison shot, you can see how the belt goes further into the slightly deep
15b With the larger diameter (1/2-inch), slightly deeper V-groove pulley, the belt stayed in place for spirited 6,800rpm, rev-limited upshifts. Note: Normally we upshift at 6,400 to 6,500 rpm, but we wanted to be sure belt-throwing was banished for good.
15b With the larger diameter (1/2-inch), slightly deeper V-groove pulley, the belt stayed
16 A simple change to March's proven underdrive pulleys helped the Nova become a more reliable driver. The alternator gauge would only drop below 14-volts if the idle speed dropped below 650 rpm when the Dart 509 was first cold started. With a warmed-up idle speed of 1,100-1,200 rpm, we didn't experience any charging system problems.
16 A simple change to March's proven underdrive pulleys helped the Nova become a more rel

17 The 10-year-old drag radials (left) had to go. We needed safer, stickier skins to hook the Nova into the 10s. The old tires still offered decent traction, but were dry-rotted badly from being outside in the elements for years before we bought the Nova. Our new (325/50R-15), Nitto NT555R drag radials were the same size as the old BFGs we were replacing. The good thing about the Nittos is they are legit street tires, unlike some other drag radials, which are not recommended for street use.
17 The 10-year-old drag radials (left) had to go. We needed safer, stickier skins to hook
18 Would you drive/race a car on this dry-rotted, cracked tire? Your author was just plain careless and crazy to baseline the Nova on dangerous rear tires. Please don't put your life on the line.
18 Would you drive/race a car on this dry-rotted, cracked tire? Your author was just plai
19a Notice the treadwear rating between the BFG Comp T/A (000) and the Nitto NT555R (100). Regular street tires usually have a treadwear rating between 350 to 600. The higher the treadwear number, the longer they last. Past experience using both brand of tires has shown us the BFG to last between 3,000 to 4,000 miles. The Nitto has lasted us roughly 5,000 miles with the same street/strip use.
19a Notice the treadwear rating between the BFG Comp T/A (000) and the Nitto NT555R (100)

19b Traction ratings (A, B or C) are mainly for wet traction combined with some dry traction. Temperature ratings are for hours of sustained highway speeds (A-over 115mph, B-100 to 115mph, C-85 to 100mph) for which the tire shouldn't heat up and blow out. At the track, we tried rear tire pressures of 24 and 20psi (hot) with both showing equal bite.
19b Traction ratings (A, B or C) are mainly for wet traction combined with some dry tract
20a It's hard to see the top of the rear tire (above left) as the Nova just begins to launch down-track. In the right picture, the Nova is about 2-feet down-track—here the rear wheel lip is about 2-inches above the top of the tire. The old school traction bars are pushing their snubbers against the front of the leaf springs causing the rear body to lift.
20a It's hard to see the top of the rear tire (above left) as the Nova just begins to lau
20b The worn-out rear shocks exacerbated this. Also notice there is no front-end rise to help transfer weight to the rear tires for better hook (and we have 60-series tires in front). Combined, these factors do not enable the tires to plant themselves as effectively as possible. Still, 10.70s are nothing to sneeze at in a heavy car that corners as well as this. Weight is 3,700 lbs with driver.
20b The worn-out rear shocks exacerbated this. Also notice there is no front-end rise to

SOURCES
Nitto Tire 6021 Katella Avenue Suite 250 Cypress CA 90630 877-565-8448 www.nittotire.com	Atco Raceway Atco NJ 856-768-2167 www.atcorace.com
March Performance 5820 Hix Rd. Westland 48185 734-729-9070 www.marchperformance.com