Dart 540ci Mild to Wild Big-Block Engine Builds - Mild To Wild Big-Blocks

Headgear for our mild combo came from Trick Flow Specialties in the form of their as-cast 320 Power Port heads.

Headgear for our mild combo came from Trick Flow Specialties in the form of their as-cast

Our mild combo started out with a set of as-cast, 320cc Power Port heads from Trick Flow Specialties. Designed as a direct bolt on, the 320 cc aluminum heads offered 137 cc exhaust ports, 122cc combustion chambers and a 2.25/1.88 stainless steel valve combo. The impressive heads offered peak flow numbers of 362 cfm on the intake and 301 on the exhaust (measured at 0.800 lift), meaning our mild combo would not be taking full advantage of their ability to support well over 700 hp. The assembled heads even featured hydraulic roller valve springs (up to 0.700 lift), guide plates and 7/16 rocker arms. The heads were installed using Fel Pro 1017 head gaskets and ARP head studs.

Working with the heads was a hydraulic roller cam and Weiand Team G single-plane intake manifold. For this mild combination, we chose an Xtreme Energy hydraulic roller cam and matching hydraulic roller lifters from Comp Cams. The XR288HR cam offered a 0.521/0.540 lift split, a 236/242 duration split (measured at 0.050) and a 110-degree lobe separation angle. Cam specs like this would be healthy on a small block or even a smaller displacement big-block, but 540 ci has a way of taming the cam considerably. The aggressive ramp rates offered by the Xtreme Energy line of cams was designed to maximize power production through the entire rev range.

Though unported, (except the CNC entry) the as-cast 320cc intake ports offered impressive flow. With peak flow number over 360 cfm, these Trick Flow heads could easily support in excess of 700 hp on the right application.

Though unported, (except the CNC entry) the as-cast 320cc intake ports offered impressive

This combo was completed with a Holley 950 Ultra HP carburetor, an MSD billet distributor and a set of 2.25-inch Hooker Super Comp headers. Additional components included an adjustable timing chain, Ultra Pro Magnum rockers and one-piece chrome-moly pushrods, all from Comp cams. Since we were running this on the engine dyno and not in a specific chassis, we chose a Pro Eliminator oil pan from Moroso.

The Moroso pan featured a number of impressive features including an internal windage tray. Moroso also included one of its trick billet oil pumps. The billet pump featured larger inlet and oil passages to increase oil flow, reduced weight compared to a cast-iron pump (by 1 pound) and increased the mounting boss cross section to help spread the load. The integral bottom-fed design eliminated the need for an external oil pickup tube, the bypass system returned oil to the pickup area to reduce aeration and oil temperature and best of all the billet pump used the stock mounting stud and oil pump shaft. Use of the Moroso pan on a production Chevy block would require drilling and tapping the block for the revised mounting holes (inline with main caps-see photo), but our Dart block was already drilled and tapped for use with this pan.

The exhaust ports measured 137 cc and flowed a whopping 300cfm at 0.800 lift. Down near the 0.550 lift offered by our cam, the exhaust pots flowed near 255 cfm.

The exhaust ports measured 137 cc and flowed a whopping 300cfm at 0.800 lift. Down near th

The finishing touch was a two-piece timing cover from Comp Cams that allowed cam adjustments and swaps without dropping the oil pan (important when swapping components to our wild configuration).

This version of our 540 was installed on the dyno with a pan full of Lucas 10W-40 oil and a tank full of pump gas. It was treated to a pair of computer-controlled break-in procedures lasting a total of 25 minutes. After a quick oil change, we were off and running. Some minor jetting on the Holley 950 Ultra HP carb was necessary and after running through a quick timing sweep to see where the engine made the best power, we were rewarded with peak power numbers of 635 hp and 646 lb-ft of torque. Though labeled mild in this instance, know that 635 hp would easily push your average Tri-Five well into the 11s, and possibly the 10s.