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475hp 347 Stroker Ford Small Block - Catching Zzzzs
Building Simple Speed With A 475hp 347 Stroker.
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.
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 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.