Richard Holdener
December 1, 2009

The game plan was to first top off the 347 with the stock 5.0L components, including factory E7TE heads, a 5.0L (stick) roller camshaft, and a GT-40 intake. Since we were replacing the factory EEC-IV management system with the FAST XFI, there was no need to run the MAF or attending air intake assembly. Having the FAST management system allowed us to quickly dial in each new combination (there were four).

In Part 1, we look at what happens when you upgrade the normally aspirated 347 stroker short-block. The stock 5.0L heads, cam, and GT-40 intake were replaced by a set of as-cast RHS aluminum heads, an XFI hydraulic roller camshaft, and an Edelbrock Performer RPM II EFI intake. Both combinations were run with an Accufab throttle body and matching EGR spacer. After dialing in the normally aspirated combinations, we will follow up by adding a Paxton centrifugal supercharger running 8 psi. For now, it is time to go into details of the first test.

The Demon 347 short-block was quickly transformed into a running motor with the addition of the necessary 5.0L-related components. The bottom end was treated to a new oil pump from Pro Comp, along with a Moroso pick up and oil pan. In went the stock 5.0L cam, along with the cam retaining plate, lifters, and spider hold-down assembly.

Next came the factory 5.0L E7TE heads. The heads featured stock (as-cast) ports but were previously modified for testing in our series "Ultimate Guide to Cylinder Heads." The improvements included machining the spring pads, and drilling and tapping for guideplates and screw-in rocker studs. This allowed us to run the heads with adjustable roller rockers on some of our larger test motors. For our needs, the as-cast ports meant they would represent the power potential of the stockers. The spring upgrade would allow us to test higher in the rev range, though the factory H.O. heads, cam timing, and GT-40 intake would surely limit anything resembling high-rpm power.

That these components were installed on the larger 347 (instead of the factory 302) would also reduce the engine speed where the combination produced peak power. Basically we had a stroker version of the stock 5.0L fuelie motor, though the static compression ratio did increase from the hike in displacement (from 9.35:1 to near 10.0:1).

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