1985 5.0L Mercury Capri Flo Tek Cylinder Head And Cam Upgrade Part 4

We've never bothered to dyno-test our Capri simply because we're having too much fun at the dragstrip with it. Not everyone can afford dyno time either, and it's much more reasonable to pay $20 at the local test-and-tune to see if your modifications have made a change for the better, not to mention that cars are meant to be driven and we'd rather talk about an adventure to the track.

We followed up with a Holley 600-cfm carburetor and Weiand intake manifold combination from Summit Racing Equipment, as well as an exhaust system from Summit and Dynomax. Performance Distributors also sent us its Firepower ignition system to give the old lump a healthy tuneup. These enhancements allowed us to chop at the clocks some more, which put the Capri's best lap at 13.55 at 99 mph. We did make a "hero run" with the serpentine belt removed and went 13.31, but we couldn't hot lap it in that trim. The 13.55 is a more accurate representation of what it can do. The 13.31, however, does hint that there is more power to unlock from the 5.0L, and we'll address that next month.

You can get the 5.0X heads in a stud-and-guideplate version, but in either case, the retail price is the same-a smoking $798 for the pair. That kind of savings leaves you cash for other speed parts, like the Ford Racing Performance Parts 1.6:1 aluminum roller rocker arms (PN M-6564-BS51) and Trick Flow Specialties 6.25-inch hardened pushrods (PN 21406250), which are a 5/16-inch-diameter rod made from 4130 chromoly. During the installation, we realized that we needed to shim the rocker arms to obtain the correct lifter preload, and we used the 0.060-inch shims from Ford Racing Performance Parts' shim kit (PN M-6529-A302).

We took this opportunity to clean the engine compartment using some Gunk engine degreaser and a power washer. We also gave the potent little 5.0L a fresh coat of high-temperature black enamel after installing the new freeze plugs that we picked up from the local auto parts store.

These premium gasket sets from Cometic obviously don't quite fall in with our extremely frugal budget for this project, but we took this opportunity to try the gaskets, and we're happy to report they work great on our 5.0L application. After screwing the new Flo Tek 5.0X heads on the Cometic MLS gaskets using a set of ARP head bolts from Summit Racing Equipment, it was time to bolt up the new clutch and flywheel from American Muscle.

The Ram HDX clutch kit (PN 34000; $184.99) features a diaphragm-style pressure plate, 10-spline clutch disc, alignment tool, and throwout bearing. It's a 10.5-inch-diameter design for '86-and-later cars, but we opted to upgrade the factory 10-inch clutch and flywheel setup from '85 using this clutch kit and Ram's billet steel 10.5-inch flywheel (PN 34012). This flywheel uses the 50-ounce balance for the 5.0L engine, it's SFI-certified, and retails for $269.99.

With the Capri up and running with the Flo Tek 5.0X heads and the B303 cam, we put as many break-in miles as we could before heading to the local quarter-mile to see what it would do. We've been having some transmission troubles with the Capri lately, so things weren't looking good, and some frigid weather-for Florida at least-didn't help the traction situation.

With the ambient temperature down around 40 degrees, there wasn't much hope for the VHT traction compound that was put down on the starting line. Still, we were armed with Toyo's Proxes slicks and a poor man's suspension that really transferred some weight.

Dropping the launch rpm to 3,000, the Capri spun slightly but moved out to a 1.92 short time. Three gear changes later, the clocks lit up with a 12.89 at 107.99 mph. It was going to be a challenge to get the Capri to leave hard without spinning, so on the next pass, we lowered the tire pressure from 15 psi to 13 psi. We also opted to rev the engine a little higher on this next run, and a 3,000-rpm launch followed by 6,200 rpm shifts turned a 1.88 60-foot time into a 12.74 at 107.88 mph. Baldwin reported that the car didn't feel like it pulled that high, so for run number four, we backed shift points down to 6,000.

Crosby followed this up with a final run of 12.61 seconds at 108.74 mph-a better 1.82 60-foot time surely helped. With a lot more air flowing through the engine and cold dense air being sucked down the carburetor, we thought it was time to try a jet change, which is something we have wanted to do for a while now, but couldn't until Holley set us up with a complete jet kit.

The staging lanes closed at this point, so this would be our last run. Baldwin took a risk and left the line at 4,500 rpm. The first 60 feet passed by in just 1.75 seconds-our best time of the night. The timing lights lit up with a 12.54 at 108.72 mph. That's a full second off our previous best e.t., and a gain of nearly 9 mph. The Capri is definitely making some steam thanks to the Flo Tek cylinder heads and the B303 cam. Not bad for budget parts.

As triumphant as the last run was, it was also the scariest looking. The car hadn't made a straight pass all night, and Baldwin went near the center line twice. The Capri wanted to launch left every time and unloaded rear tires pretty good at every shift, so we think we have some suspension work ahead of us. With the help of Lakewood Industries and Moroso, that's our plan for next month. We're also going to finally drop the front antiroll bar (yes, it's still on there), as well as maybe add a few more ponies with a couple of small bolt-ons that we've passed by. Are 11-second e.t.'s possible for our Capri? Come back next month and find out.