Steve Baur
Former Editor, Modified Mustangs & Fords
May 27, 2010
Photos By: Justin Cesler

It's hard to believe, but the '85 Mercury Capri that we've been modifying over the last several issues is now 25 years old. That's two and a half decades since it rolled off the assembly line with its 5.0L powerplant and five-speed manual transmission. Overall, it's in pretty good shape for a four-eyed car, which so often are found beaten, abused, and generally thrashed.

We took the opportunity to modify this near-stock example with commonly available, budget-friendly speed parts and have had a great time running it at the dragstrip. After stopping the clocks in a staggeringly slow 15.10 seconds at 91 mph, we began modifying the Capri, first with a set of lightweight Weld Racing Draglite wheels from Summit Racing and Toyo Proxes 26x9 slicks and skinnies. We bumped the timing and powershifted the T-5 transmission to a best time of 14.46 at 92.9 mph. Then we broke the stock 7.5 rear differential.

MPS Auto Salvage set us up with a used 8.8 axle assembly, and we stuffed it with Moser 28-spline axle shafts and a 3.73 Richmond ring and pinion, all from Summit Racing Equipment. We were then able to whittle the 60-foot time down and improved our quarter-mile e.t. to a 14.26 at 94.10 mph before dropping on a new Holley 4160 600-cfm carburetor. That put us down to a 14.14 at 94.9 mph. From there, we installed a new ignition system from Performance Distributors, as well as a Weiand Street Dominator dual-plane intake manifold from Summit Racing Equipment. With these parts, e.t.'s dropped to 14.06, 14.04, 13.98, and a 13.94 with trap speeds attaining 97 mph. Our 60-foot times dropped as well, into the high 1.8-second range.

Next on our agenda was to change out the factory exhaust system for some tried-and-true aftermarket dual-exhaust versions. Summit Racing provided us with a set of Flow-tech 15/8-inch long-tube headers and an off-road H-pipe, while Dynomax shipped us one of its Ultraflo stainless converter-back exhaust systems.

Having opened up the induction side of the engine, we figured that the stock two-to-one-to-two Y-pipe configuration had to be choking the air pump, and we were right. With the new exhaust system installed, the Capri was solidly in the 13s and logged a 13.64 off the trailer, followed by a 13.62, 13.66, and a 13.63. Raising the launch rpm from 4,500 to 5,500 rpm produced our best e.t. to date-a 13.55 at 100 mph. We then chucked the serpentine belt, raised the front tire pressure to 50 psi, and let the clutch fly. The Capri responded with a 13.31 at 102 mph.

We were pretty impressed with the Capri's performance up to this point, and like most of our readers, we always want to go faster. To that end, we called up Tri-State Cylinder Heads and ordered a set of its very budget-friendly Flo Tek 5.0X cylinder heads. Summit Racing sent us a Ford Racing Performance Parts B303 hydraulic roller camshaft, as well as Trickflow Specialties pushrods and Ford Racing roller rocker arms to complete the installation. Cometic's Streetpro gasket kit was used to seal up the 5.0L, and we backed up the newly fortified powerplant with a Ram HDX clutch and Ram billet-steel flywheel from AmericanMuscle.com.

There was simply no reason to expect the stock clutch to handle the extra power and continued track abuse, so while the engine was out, we installed the new clutch, which is a half-inch larger in diameter than the factory piece it replaced. The extra surface area would be beneficial to our cause for sure.

Despite cold temperatures and a track surface that could not sustain our previous 5,500-rpm launches, we slashed our e.t.s's considerably and ran a 12.89, a 12.74, a 12.61, and finally a 12.54. We made a significant increase in trap speed as well, with the Capri now running around 108 mph out the back door.

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