The "Shrinker" (Bruce Robertson) is a long time member of the Blackjack team and has been developing this new Carburetor for some years. With the Blackjack team developing this new engine combination after selling their original injected engine an opportunity for testing arose. Des Curnow, the owner of Blackjack Racing is a big fan of mechanical injection because of the ease of setting the tune and in his own words, "We had excellent, consistent tunes with the old motor. For this new splayed valve head small block we decided to try carburettors with a tunnel ram in the search for more power."

"This engine is a Rocket small block of 412 cubes producing 900 plus horsepower fitted with a Top Fuel spec crank and rods suitable for supercharging later on in the development. David Handley handles the engine requirements for us. The exhaust is all Gonzo's work consisting of Tri-y's, megaphones, double barrel silencers and a full x-crossover. We ran the car without the silencers once but it was that noisy we won't do that again, we don't want to damage the driver any more than necessary," he laughed.

"The ignition is a billet drive MSD dizzy for the 18736542 firing order. The timing is controlled by an MSD ignition controller that is crank triggered with the spark energy supplied by a MSD 10-Plus for kick-ass ignition reliability if we go blown. The heads are GM splayed valve, the cam has roller bearing journals with a Jesel adjustable belt drive. "Tony Dominello looks after the transmission and the torque converter is designed by him to our requirements. The transmission is a TCI Dedenbear Powerglide Low Drag Supercase with internal liner and internals built to withstand a blown engine. The driveline is made up of a Mark Williams aluminium drive shaft turning Pro Gears because we break the others.

"The Blackjack records show that the Commodore launches with G-forces of 2.45 g's with 60' times of 1.153 sec. 50 mph takes 1.000 second and 100 mph is achieved 2.855 seconds out. We use a 3-step rev limit control to manage the wheel speed in the burnout and keep the launch and engine revs safe during the run. We use Hoosier tyres exclusively as we have tested all the others and these are incredible.

When we posed the question "Why develop an all-new carburetor?"
The answer provided by The Shrinker was very detailed and we couldn't write quick enough to get it all down on paper so we decided to let him type it in his own words. Here they are... The conventional Holley carburetor has seen years of satisfactory service in drag racing fields. However many people only perform basic tuning of the fuel circuits provided. Most people are limited to changing the main jets and the idle mixture screw settings. By learning how to utilise the idle and transfer circuits correctly and by setting the main circuit fuel curve, engine power can be vastly improved. A conventional booster-style venturi carburettor is usually preset to control the main circuit fuel curve by controlling the volume of air introduced to the spread pattern of air bleeds in the main air well. Other important controlling influences are main jet size, power valve jetting and setting, transfer jet fuel consumption, booster and main venturi sizing and shaping, fuel flow rates through the needle and seat, float drop rates, fuel bowl pressure (vent design).

The problem we had with the conventional booster style carburettor was the time necessary to tune them and the special tooling needed to modify the jetting etc. Fuel drainage and wastage was a problem and tuning the carburettors for quickly changing atmospheric conditions was a 20-minute exercise.

I have been developing and testing these carburetors for seven years and with the new Blackjack engine being carburetted and fitted with a tunnel ram, the team had to quickly solve the carburetion. With the patent pending quick change carby, preset tuned plates can be installed in seconds. All the fuel is left in the carby. In practice it means that you can read the atmosphere at the latest possible time in the staging lanes and select a tune-up. If the racing is delayed you can reset the tune quickly.

The tuning of the main circuit fuel flow curve is vastly simpler than in a booster style carburettor. The unique design of the main jet gives a flat fuel curve through all air flow ranges of operation. Dyno tests have shown instant flat fuel curves at whatever ratio you select it to be. There is no need to understand complex emulsion well tapers and air bleed influences or other difficult concepts, you simply select a larger jet for more fuel flow. The main jet system is also separated from the transfer system, so altering the main jet size has no influence on the idle and transfer fuel quantity.