Like any new combination, the initial 13.68 run was more of a shakedown pass to make sure nothing leaked and the car went straight; hell, the paint was still tacky from being sprayed the night before. (Seriously, you could smell the paint as you walked by-from five feet away.)
Our second pass with the 830-cfm Holley produced a traction-limited 12.34 at 121.17 mph out of the box. That's big mph, but it didn't hook, making the e.t.'s less than impressive. Back in the pits, checking the plugs revealed a lean condition, so Consolo fattened it up by blocking off the power valves and went up 10 jet sizes from 78 to 88s on both the primaries and secondaries. The result: a gain of 2.4 mph! The added traction dropped us well into the 11s with an 11.38, but the 123.59 mph was the real indicator of what the added fuel did.
It was only 11 in the morning and the temperature was 98-and climbing. We splashed the launch pad with a little VHT traction compound and were rewarded with an impressive 11.32 at 123 mph. For the second pass, once again the power valves were blocked and this time, the jets were bumped up eight sizes to 88s, netting us with an 11.29 at 126.65 mph.
Stepping up to the 830-cfm HP series was impressive, to say the least. During the first pass, we experienced a bit of hesitation out of the gate; regardless, the HP seemed to be the ideal match for our 415ci bullet with an 11.02 at 126.88 mph. To eliminate the stumble, the 28/29 squirters were swapped for a set of 37s. We won't deny it; it was a drastic change and ideally, you should only step up a couple of sizes at a time. The truth of the matter was our track time was running short. On top of that, we also jumped eight sizes on the jetting, from 86s to 94s. It worked; we bettered our e.t. with a 11 flat, which we'll attribute to better traction; however, the mph was similar. Still, we got rid of the stumble, and the Nova motored strong all the way through the traps. Again, if we had the extra time, we would have leaned out the combination by dropping a couple of sizes in both the squirters and jets, but that's another story for another day.
If you're wondering what's different between the conventional 830 versus the HP series 830, the HP comes with down-leg-style boosters, whereas the standard 830 has annular-style boosters. Other differences for the HP are stainless steel throttle plates with button-head screws, power valve blow-out protection, and nonstick gaskets.
Originally, the 830-cfm HP was going to be the final carb of the day, until we learned QMP had a 950-cfm HP sitting in its tow rig. Even with the limited time, we decided to give it a shot-and saw nothing less than a half-dozen arms flinging like mad to finish the swap.
From Holley, the 950 HP is jetted with 78s on the primaries and the secondaries, 31/31 squirters, and 6.5 power valve on both sides. This particular carb already had the power valves blocked (notice the trend?), was jetted with 84s all around, and was sized with a 35 squirter. Needless to say, this was the money run; the great pumpkin hooked and flew through the big end with a 10.89 at 127.58 mph run. Not a bad way to end the day!
We swap four Holley carburetors and tune for maximum e.t. and mph at the dragstrip.
Stock-suspension '71 Nova with a 415ci small-block, 28x12.5-15 Mickey Thompson ET Streets.
Carburetors start at $410.
Engine: 415ci small-block
Intake: GMPP Bow Tie single-plane
Cylinder: heads Dart Iron Sportsman II
Camshaft: Custom solid-roller (around 275 duration)
Pistons: SRP flat-tops
Rods Eagle: H-beam
Crankshaft: Eagle 4340
Front Suspension: Stock w/Lakewood 90/10 struts
Rear Suspension: Stock w/Lakewood 50/50 shocks & traction bars
Transmission: Turbo 400 w/10-inch 4,000-stall converter
Rearend: 10-bolt w/4.10:1 gear