If you've been reading Muscle Mustangs & Fast Fords for a while, you may have seen our subject notchback, dubbed the Little Juice Coupe, in numerous articles as we have taken the AOD-equipped slug and transformed it into a true street fighter.
Since the last installment "The Last Stand" (Oct. '08), we have swapped out the TCI torque converter for one with a slightly higher stall speed. The car responded with a best-ever motor-only pass of 13.34 at 102 mph. Sixty-foot times dropped nearly a tenth of a second on the motor. The higher stall speed converter really helped the car on nitrous, as it allowed the engine to rev to the window switches set point of 3,000 rpm right at the launch. Short times dropped to 1.75 seconds, and we set a new best elapsed time of 11.78 at 117 mph. In addition to the new and faster quarter-mile e.t.'s, we were able to drive the car an hour and a half to and from the track, while recording 20-22 mpg.
As much as we were happy with the way our Pony was performing, there was still something missing from the package. The Flowmaster exhaust let's you know this Mustang is modified, but the stock sounding idle just screamed mundane. To that end, we decided to swap in a high-performance camshaft to give the idle some spunk. There are currently tons of camshafts available for the 5.0L Mustang, and they offer a price range that is just as broad as the cam selection. Our main goal was for the car to sound good, and if we picked up a few ponies along the way, that was cool too.
Ford Racing Performance Parts was one of the first companies to offer high-performance camshafts for the 5.0L, and they are still popular today, both for the increased performance they offer, as well as the relatively minimal cash outlay that it requires. Probably the most popular of the FRPP grinds is the E303 camshaft. Part number M-6250-E303 is a hydraulic roller camshaft that offers an advertised duration of 282 degrees on both the intake and exhaust sides, and it will lift the valves .498-inches off the seat. The cam is the only FRPP camshaft that is 50-state legal and it carries its own CARB E.O. number to prove it.
Another one of Ford Racing's performance camshafts that we considered was the B303 cam. Offering 284 degrees of advertised duration and .480 inches of lift, the B303 (PN M-6250-B303) is actually better suited for use with nitrous thanks to its extended duration. After talking with the folks at the Ford Racing Performance Parts tech line, we opted for the E303, as the B303 drops a bit of bottom-end torque in exchange for a higher powerband. We wanted that torque since the car spends far more time running on the motor than it does on the bottle. Either cam would work well with our GT40X Turboswirl cylinder heads and Cobra intake manifold, and piston-to-valve clearance wouldn't be a problem with the 1.94 intake valves that the heads featured.
Prior to the camshaft swap, we were running FRPP 1.7:1 bolt-down roller rockers along with the stock cam. This combination offers .472-inch lift versus the stock .444-inch measurement, and while it produced good power for our coupe, it just didn't sound aggressive enough. After choosing to go with the E303 camshaft, we employed FRPP's 1.6:1 bolt-down roller rockers, and installed a new timing chain (PN M-6268-F302) set along with a hardened cam thrust plate.
Installation is a bit involved, and if you've never opened up your 5.0L before, this might not be the best time to do so. We had the job knocked out in about eight hours, taking our time as we went. The Little Juice Coupe fired right up, and after we set the timing, it crackled just like we had hoped. After the swap, we took the car back to HP Performance in Orange Park, Florida, for a little dyno testing and saw that horsepower increased from 4,300 rpm upward, and recorded a peak horsepower increase from 265 to 273 at the wheels. Torque stayed relatively the same.
No, we're not doing a 4.6L Modular cam swap. Ford Racing sent us both its E303 and B303 ca
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