Richard Holdener
March 5, 2014

Knowing we had enough head flow to meet our goals, we turned our attention to the camshaft and intake manifold. Crane supplied a dual-pattern, solid-roller profile that offered a 0.746/0.732 lift split, a 272/280 duration split, and 114-degree LSA. Healthy by any standard, the cam was teamed with a set of roller lifters; an adjustable, billet, double-roller timing chain; and hardened pushrod all from Crane Cams. Crane also supplied the necessary 1.73-ratio, aluminum roller rockers and timing button to keep the roller cam properly located. Though available for flat-tappet and hydraulic roller applications, the Kaase heads were equipped with roller springs designed for cams up to 0.800-inch lift. Topping the heads was an Edelbrock Victor 460 intake designed to accept a 4500-series Dominator carburetor.

Feeding air and fuel to the stroker was a Holley 1150 Ultra Dominator. The word trick hardly does justice to these new carburetors from Holley, but know that the thing was nearly spot on right out of the box. We tried changing jets just because we felt guilty about not doing so, but were rewarded with changes of just a couple horsepower.

To illustrate the impressive power offered by the Kaase heads, the 557 stroker was run with an Aeromotive fuel pump, an MSD ignition system and 2.25-inch Hooker headers. Filled first with Lucas break-in oil and a bottle of (high-zinc) break-in additive, the Milodon pan was eventually filled with 5W-30 synthetic for the power runs.

After a pair of break-in cycles and some timing sweeps, the 557 eventually spit out 754 hp at 6,300 rpm and 713 lb-ft of torque at 4,700 rpm. Remember, this was with a static compression ratio below 10.5:1 and a simple oiling system (meaning no windage tray). We noticed the big motor was very sensitive to oil level and having too much oil limited power. In fact, the power climbed each time we drained a quart out until we started to get a drop in oil pressure. What this motor really needed was a windage tray—our fault, not Milodon's, as it only supplied what we asked for.

Satisfied with our normally aspirated power, we added a small shot of nitrous. NOS supplied an adjustable Cheater (plate) system designed for our 4500-series Holley Dominator. Adjustable from 150hp to 250hp, the system was perfectly suited for our street-strip application.

Math told us the 750hp 557 stroker would require the full 250hp shot offered by the kit, so we started with 200hp jetting. After installing the solenoids on a billet Wilson nitrous plate, we made sure to elevate the internal pressure to just over 1,000 psi (bottle temp at 92 degrees).

After minor adjustments to the independent fuel pressure supplied to the nitrous solenoid, the NOS-fed 557 responded with peak numbers of 1,014 hp and 935 lb-ft of torque. Imagine having 1,000 hp at your fingertips after swapping this fire-breather into a light Fox Mustang?

7 Not wanting to restrict the Kaase heads, we installed an Edelbrock Victor 460 designed to accept a 4500-series Holley carburetor.
8 Big motors need big carbs so we installed this 4500-series, 1150 Ultra Dominator carb from Holley.
9 Even though we were running a roller cam in this stroker, we opted to augment the Lucas break-in oil with a bottle of (Zinc-Plus) break-in additive.
10 Spark energy is crucial on a high- performance stroker, so we installed this MSD billet distributor. The distributor was combined with an MSD Digital 7 amplifier and Blaster coil.
11 Finishing touches on the 557 stroker included a Milodon oil pan, 2.25-inch Hooker headers, and a K&N oil filter. After the break-in procedure, oil change and some carb tuning, we were rewarded with 754 hp at 6,300 rpm and 713 lb-ft of torque at 4,700 rpm. True to form, the stroker excelled in torque production, exceeding 650 lb-ft from 3,700 rpm to 5,900 rpm.
12 Wanting even more power, we elected to install this plate nitrous kit from NOS designed specifically for the Dominator carb.
13 Though the kit included mounting tabs for the fuel and nitrous solenoids, we installed them on this trick plate from Wilson Manifolds.
14 Activating the nitrous on the big-inch Ford resulted in some serious power gains. Running 200hp jetting and tuning with bottle and fuel pressure, we were eventually rewarded with peak numbers of 1,014 hp and 935 lb-ft of torque.

BBF Head Flow Comparison

Super Cobra Jet vs. Kaase P51
Super Cobra Jet Kaase P51
Valve Lift Intake Exhaust Intake Exhaust
0.100 70 52 105 103
0.200 154 103 175 137
0.300 202 139 258 170
0.400 248 185 330 199
0.500 274 200 375 223
0.600 298 208 395 242
0.700 309 212 401 251

Kaase P-51 Cylinder Head Specs

Intake runner volume 310 cc
Exhaust port volume 145 cc
Intake valve diameter 2.250 inches
Exhaust valve diameter 1.760 inches
Chamber volume 72cc