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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With us launching the car at about 3,500 rpm and our short times off by about a tenth of a second, we knew there was more in the car, but we also needed to address the suspension before we headed to the track again. The car didn't go straight on any of the most recent passes, and our drivers reported that the Capri wanted to dart right on every shift.

To remedy our suspension woes, we called up Lakewood Industries and ordered 90/10 front drag struts and 50/50 rear shocks, as well as upper and lower rear control arms. Lakewood also sent us a driveshaft loop, which we actually should have installed long ago when we started running the car on slick tires.

To help with weight transfer, we called up Moroso and ordered a set of the company's legendary Trick Springs for the front. After cutting out two coils, we stuffed them in and then got to installing our Hurst SST billet shifter for the T-5 transmission. The SST shifter (super short throw) comes with a chrome retro stick and white shift knob, and features very short, and precise, shift throws.

To help us dial in our carburetor without resorting to reading spark plugs, we installed Holley's wideband air/fuel meter. It's a pretty simple installation and provides accurate, real-time air/fuel metering so you can make accurate carburetor changes for increased performance.

Holley also sent us a jet kit, rebuild kit, and a trick kit for the 4160 Holley carb we're using. We also got a copy of Holley's carburetor installation and tuning DVD, which should be a must-watch item if you're going to start tuning the four-barrel fuel mixer and don't have much experience with a carburetor.

With our latest round of tweaks, we went to Gainesville Raceway in Gainesville, Florida, where we unloaded the Capri and made ready for some quarter-mile fun. Until this point, we had been worrying about the increasingly bad shifting issue with the stock T-5 transmission. It appeared to be a bad Second gear synchronizer, but it was really only a problem when driving the car in a normal fashion. At wide-open throttle, it was more or less fine. This was not to be the case for our last test session, as we managed to find Second on a couple of occasions. Furthermore, the stock 8.8 Traction-Lok differential was throwing in the towel, and the vast majority of our runs featured just one wheel with traction.

That being said, we finished the day with a best e.t. of 12.56 seconds at 108.79 mph. On one pass, we logged our best 60-foot time, which was a 1.72-second effort. On another, we hit 109.35 mph-the first and only time we ever got past 108 mph.

There's definitely more in the Capri as it sits, and adding an electric fan and a set of race pulleys has to be worth a couple of tenths as well. There's probably a solid 12.2 performance in the car-and this is a fully loaded and equipped Mercury we're talking about. That being said, the scale at Gainesville did show the Capri to be a svelte warrior at 2,940 pounds without a driver.

We'd like to thank Summit Racing Equipment and all of the other companies that helped make our Mercury fly. They made it really easy to go fast. We also need to thank the car's owner, Dave Bohnsack, for letting us whip on his 5.0L, as well as George Xenos, Brian Bohnsack, Rob Baldwin, Mark Johnson, and Chris Crosby.

We don't necessarily like going out with a fizz, as opposed to a bang, but next month, we will debut our new NMRA True Street project car. It's another early Mustang that should have the foureyedpride.com guys all excited, and it's going to be another carbureted build as well.

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