As expected, the 540 Dart motor offered an exceptional torque curve, with torque production exceeding 600 lb-ft from 3,300 rpm to 5,500 rpm. Remember our previous comment about the single-plane intake hurting low-speed torque production? Do you think you will really be able to harness 600 lb-ft of torque at 3,000 rpm? That is the great thing about large displacement motors, the abundance (or excess) of torque. No need to rev one to the moon to get decent motivation; just step on the gas and let the cubes do the work. Best of all, this simple combination should offer literally thousands of miles of trouble-free motoring, not to mention create more than a few furious Ford owners.
Wild 540 Combo
After our success with the mild combination, it was time to step up to something a bit wilder. In this case, it meant swapping out the heads, cam and intake. The as-cast Trick Flow heads were replaced with a set of CNC-ported Dart Pro 1s, while the hydraulic roller cam was ditched in favor of a more aggressive solid-roller design. On the intake side, we ran the new combo both with the single-plane Weiand Team G as well as a dual-quad tunnel ram (a Weaind Hi-Ram). The Team G was used so we could mount the NOS Cheater Competition nitrous system, while the tunnel ram was installed because tunnel rams are inherently cool. We know, you have to cut a hole in the hood, synch the linkage and they are less than ideal in the rain, but tunnel rams make lots of power and are flat-out bad to the bone.
The remainder of the 540 remained unchanged, including the Dart SHP short-block, the oiling, ignition and exhaust systems. Even the static compression ratio remained relatively unchanged due to a difference of less than 1cc between the chambers on the Trick Flow Power Port and Dart Pro 1 heads.
The Dart Pro 1 heads featured full CNC porting that produced 345cc intake ports and 129cc exhaust ports. The precision-machined and ported heads offered a 2.30/1.88 valve combination, a Vasco-Jet spring package (max 0.790 lift) that offered 250-pound seat pressure to work with our solid roller cam and impressive flow numbers. According to Dart, the Pro 1 heads flowed 397 cfm on the intake and 280 cfm on the exhaust (using the Dart-supplied valves). This is enough airflow to support 800 hp, meaning more than enough for our low-compression 540. The Comp solid roller cam for our wild combination offered a 0.742/0.715 lift split, a 271/280-degree duration split and a 112-degree lobe separation angle.
Topping off the new Dart heads and solid roller cam was a Hi-Ram tunnel ram intake and a pair of 950 HP carburetors. Before you get all up in arms about us effectively doubling the amount of carburetion, know that the 950 HP is actually a 750 HP body with an 850 base plate. Sure, the combination would likely work well with a pair of smaller carbs, but the 950 HP combo metered perfectly on our roller-cammed 540, even down at 3,000 rpm. We took the liberty of setting up the linkage prior to the swap, so installation of the Weiand tunnel ram was no more difficult than a conventional intake swap. Since no break-in procedure was necessary with the roller cam, all we had to do was adjust the valves and start tuning. Thanks goes to Westech's Steve Brule for all his hard work on making the SHP test sessions go smoothly. As it turned out, very little tuning of the 950 HP carbs was required from their out-of-the-box condition. The wild 540 ran best with 38 degrees of timing and after the tuning sessions were over, the big-block pumped out 777 hp and 681 lb-ft of torque.
The new combination shifted the power higher in the rev range compared to the previous mild combo. Where the mild combo produced peak power at 5,700 rpm and peak torque at 4,600 rpm, the wild combo elevated the horsepower and torque peaks by 1,000 rpm, to 6,600 rpm and 5,600 rpm, respectively.