Once we had the headgear in order, we took care of the rest of the induction system and cam timing. Topping off the Z304 heads was the tried-and-true Edelbrock Victor Jr. intake and a Holley 750 HP carb. Right out of the box, the combination provided a balanced air/fuel curve along with plenty of power. The single-plane intake also helped tailor the power curve slightly higher in the rev range compared to a dual-plane. Initially, we wanted to utilize the Z303 cam profile from FRPP, but some digging revealed that the 347 crate motor was actually equipped with an even wilder cam. Unlike the single-pattern Z303, the crate motor cam offered a dual pattern with more lift and duration.
The Z304 heads featured M-6513-BH...
The Z304 heads featured M-6513-BH beehive springs designed to provide 130 pounds of seat pressure (at 1.800 installed height) and 293 pounds of open pressure. The springs allowed over 0.650 lift, which was more than enough for our Z303 cam.
Were this a 302, we'd likely opt for the smaller Z303, but since we had the extra displacement working in our favor, we decided to step up to the slightly bigger crate motor cam. According to the catalog, the cam used in the crate motor offered 232 degrees of intake duration and 240 degrees of exhaust duration. The duration figures were combined with a 0.563/0.584-inch lift split. Since FRPP did not list this cam in its catalog, a little research on our part netted this grind in the Comp Cams catalog under the heading XE282HR.
With the power producers taken care of, we needed a short-block in which to put them. Turning to Coast High Performance, we decided that one of its Street Fighter stroker motors best fit the bill. The CHP 347 featured a brand-new production two-bolt block stuffed to the gills with a 3.40-inch stroker crank, forged connecting rods, and matching forged pistons. Though Coast High Performance offers a steel crank, we decided the cast crank was good enough for our street motor. Having never broken a crank (cast or otherwise) from sheer power production, we felt safe with the cast version in this application. The CHP internals included forged pistons with valve reliefs for both inline and Trick Flow Twisted Wedge heads. Naturally, the CHP short-block included new rings and bearings, along with the necessary precision machine work.
Since we received the short-block assembled, all that was necessary was to install the Comp cam, Z304 heads, and Victor Jr. intake. We also took the liberty of running a set of 1 3/4-inch Hooker Super Comp Headers, a CSI electric water pump, and an MSD ignition. The Z304 heads were installed using Fel-Pro 1011-2 head gaskets and ARP head studs.
 The 63cc combustion chambers...  The 63cc combustion chambers featured CNC finishing to improve flow. The chambers were home to a set of stainless steel 2.02/1.60 valves. |  The exhaust flow was equally...  The exhaust flow was equally impressive, with the FRPP heads posting flow numbers of 221 cfm at 0.600 lift. |  To maximize sealing, we employed...  To maximize sealing, we employed a set of Fel-Pro 1011-2 head gaskets and ARP head studs. Though a tad overkill for this street motor, who knows if we might get greedy and run some boost on this combination in the future. |
The FRPP 347 crate motor was rated at 450 hp, and we were hoping that our combina-tion would equal that power output. Before running the new motor in anger, we subjected the stroker to a 30-minute break-in period.After we were convinced that the rings had become properly acquainted with the cylinder walls, we replaced the conventional oil with Lucas synthetic. A few full-throttle loads on the dyno indicated that the jetting in the Holley 750 HP carb was spot on. The timing curve from the MSD distributor was locked in place at 34 degrees (the setting that produced the best power curve). After just two pulls, we were rewarded with peak power numbers of 478 hp and 434 lb-ft of torque. Torque produc-tion from the stroker exceeded 400 lb-ft from 3,800 rpm to 6,100 rpm, making for one sweet powerband.
We were hoping to reach the 450hp mark, but we exceeded that number from 5,700 rpm to 6,700 rpm. There was a small price to pay for the healthy Xtreme Energy cam employed in this stroker. Both idle and low-speed driveability were diminished slightly compared to a milder grind, but it's hard to argue with the power production of such a simple stroker. Install this 347 in a Fox Mustang , and you're ready to go out and catch some Zs.
 The Z304 heads required M-6564-F351...  The Z304 heads required M-6564-F351 roller rockers. The rockers ensure accurate valvetrain geometry to make the most of the available cam lift and duration. |  We Reached into the parts...  We Reached into the parts bin and grabbed a set of Hooker Super Comp Mustang headers for use on this 347. The 1 3/4-inch headers were run through a 3-inch dyno exhaust system. |  The 347 stroker was run sans...  The 347 stroker was run sans accessories, so we employed this CSI electric water pump to keep things cool. |
 Holley supplied one of its...  Holley supplied one of its 750 HP series carbs for our testing. The Holley carb worked perfectly right out of the box on this stroker motor. |  Is it possible to build a...  Is it possible to build a 302 that will knock out nearly 480 hp? The answer is obviously yes, but such a combination would be considerably more radical than this 347 version, and the smaller 302 would produce nowhere near as much midrange torque as the stroker. By equipping the 347 with Z304 heads and the 232/240 hydraulic roller cam, we were able to produce peak numbers of 478 hp and 434 lb-ft of torque. It's always possible to increase the power output with more cam timing, compression, and obviously cubic inches, but this little stroker would make one heck of a street motor, not to mention making life difficult for a few Z28s. |  Run with a single-plane Victor...  Run with a single-plane Victor Jr. intake and Holley carb, the 347 produced 478 hp and 434 lb-ft of torque. |