1985 5.0L Mercury Capri Flo Tek Cylinder Head And Cam Upgrade Part 4
Our Mercury Capri Gets A Cylinder-Head And Cam Upgrade From Flo-Tek And Summit Racing Equipment.
From the June, 2010 issue of Muscle Mustangs & Fast Fords
By Steve Baur
Photography by Justin Cesler, Steve Baur
In the last few issues of MM&FF, we've been modifying an '85 5.0L Mercury Capri with bolt-on parts from Summit Racing Equipment, Performance Distributors, Holley, Weiand, Dynomax and Weld Racing. The modifications have allowed us to take this once-sluggish 15.6-second ride to a mercurial 13.31 at 102 mph. This month, we aim to improve on this accomplishment with the addition of high-performance cylinder heads and a hot camshaft.
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.
To recap the present state of our mighty Mercury, we started with a mostly stock 5.0L Capri, its only modifications being an Edelbrock 750-cfm carburetor, 3.73 gears, and a pair of Flowmaster mufflers. We spent the first track session learning what the car responded best to with regard to shift and launch rpm. We then added lightweight Weld Draglite wheels and Toyo Proxes 26x9-inch slicks and skinnies, and we bumped the timing. With these changes, we whittled the quarter-mile time down from a 15.44 to a 14.26, picking up about 5 mph in the process.
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.
We had a leaky freeze plug...
We had a leaky freeze plug and some very brown coolant that told us we needed to change all of them. That combined with the fact that we were going to put a new clutch in made the decision to pull the entire drivetrain much easier. Here, George Xenos and Chris Crosby drop the newly Flo Tek-crowned 5.0L back in.
This month, though, we promised to bolt on a set of high-performance cylinder heads and a hot camshaft, and we did just that. We went to Tri State Cylinder Head and ordered a pair of its Flo Tek 5.0X aluminum cylinder heads designed for pedestal-mount rocker arms. The 5.0X heads feature 180cc intake runners, 1.94-inch intake/1.54-inch exhaust valves, 58cc combustion chambers, and valvesprings good for cams with 0.550-inch lift. They also feature hardened locks and retainers, manganese/bronze valveguides, and phosphor/bronze exhaust guides, as well as a five-angle valve job.
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).
At just $800 for the pair,...
At just $800 for the pair, Flo Tek's 5.0X aluminum cylinder heads are a sweet bargain, and more importantly, they perform very well.
For our camshaft selection, we had a myriad of choices, even with the limitation of the stock piston valve reliefs. When it came down to ordering one, we went with a Ford Racing Performance Parts B303 camshaft. The venerable M-6250-B303 camshaft offers 224 degrees of duration at 0.050 on both the intake and exhaust (284/284 advertised), and 0.480-inch of valve lift. It's a great cam for the average street car as it offers a great burbling idle sound and an increased rev range to 6,000 rpm. Best of all, it's just $195 through Summit Racing Equipment, which provided us with the cam, rocker arms, and the pushrods for this buildup.
Available in either pedestal-...
Available in either pedestal- or stud-mount form, the 5.0X heads feature a 180cc intake runner. This should provide plenty of air whether you have a little 302 like us, or a 347 stroker.
The Flo Tek heads offer a...
The Flo Tek heads offer a 1.94 intake valve and a 1.56 exhaust valve.
For our valvetrain choices,...
For our valvetrain choices, we turned to Summit Racing Equipment. Summit set us up with a Ford Racing Performance Parts B303 camshaft, FRPP 1.6:1 rocker arms, and a set of Trick Flow chromoly pushrods. These are a relatively inexpensive parts, but they are proven performers and worked well in our mild street application.
After replacing all of the...
After replacing all of the freeze plugs in the engine, giving it a fresh paint job, and cleaning the deck surface, we were ready to reassemble the 5.0L powerplant. Here George Xenos uses a long bolt to install the camshaft, along with some Royal Purple Max-Tuff assembly lube on the cam journals.
Xenos then installed the factory...
Xenos then installed the factory cam retaining plate, followed by the timing chain that Summit sent us. With the engine at top dead center, we simply matched the dots up on the gears for a "straight up" installation.
The timing cover was next....
The timing cover was next. We really like Cometic's timing cover gasket, as it is a thick sturdy piece, not just a flimsy strip of gasket material.
Cometic Gasket's multilayer-steel...
Cometic Gasket's multilayer-steel gaskets may be a bit overkill for this mild street application, but they are sure to provide years of cylinder sealing, probably far more than the stock rings will last.
At our last track outing, we came to realize we had a leaky freeze plug. With a brown watery substance residing in the radiator, we knew the other freeze plugs couldn't be far behind in rotting away in the block. This problem combined with the fact that we were going to install a new clutch from American Muscle, led us to the conclusion that pulling the entire engine and transmission was the best course of action. Once you have the cylinder heads and the transmission out of the car, there are just the two motor mount bolts and the engine comes right out.
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.
With the change to aluminum...
With the change to aluminum for the cylinder-head construction, we'll be dropping about 40 pounds off the nose of our Mercury Capri by using the Flo Tek heads from Tri-State Cylinder Head.
In order to put the engine back together, we called Cometic Gasket and ordered its Streetpro top-end gasket kit (PN Pro1016T), which retails for $315.95, as well as the Cometic's conversion kit (PN Pro1015B), which sells for $134.95. The top-end kit includes the intake manifold, exhaust manifold, EGR, valve cover, carburetor, and thermostat housing gaskets in addition to several others. It also includes Cometic's MLS (multilayer-steel) head gasket set. The conversion kit includes the timing cover, oil pan, rear main, and water pump gaskets.
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.
Summit Racing also provided...
Summit Racing also provided us with a set of ARP head bolts to replace the factory torque-to-yield fasteners. We lubricated the fasteners and washers with engine oil; then torqued them to 85 ft-lb in three increments.
We knew the heads and camshaft modifications were going to add a lot of power to the combination, and while we didn't really have any clutch problems at the track thus far, we'd be asking for trouble once the engine went back in with the hot parts. To that end, we called up Americanmuscle.com, which steered us towards Ram Clutch's HDX series clutch kit.
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.
If you can't get your threaded...
If you can't get your threaded inserts out of the factory heads, then you'll need to find replacements. Ours came from Trick Flow Specialties by way of Xenos.
Ram says the HDX clutch is good for 450 hp, which is far more than we'll be making, but considering the track abuse it will receive, it probably can benefit from some padding in the numbers. We managed to put a couple of hundred miles on the clutch before letting the hammer drop-Ram recommends a minimum of 500 miles for proper break-in. As long as you don't have any deadlines looming, it should be pretty easy to accomplish that before your start banging gears. Amercianmuscle.com makes it easy to shop for your Mustang as it has a great website with parts grouped by model year.
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.
The Ford Racing rocker arms...
The Ford Racing rocker arms we used are a bolt-down pedestal mount version just like the stock steel rockers.
Previously, we had Capri crew chief George Xenos turning the wrenches and banging the gears while we took the pictures, but Xenos decided it was time to earn a real living and went back to full-time work, so we had to find another wheelman. We found two in Rob Baldwin and Chris Crosby, both of whom had pitched in on the project at one time or another. Baldwin got the nod for his proper powershifting performance of former project car Little Juiced Coupe at the track, so we kept the rookie Crosby on reserve for later.
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.
Xenos then torqued the Weiand...
Xenos then torqued the Weiand intake manifold to 20 ft-lbs.
Combined with the Trick Flow...
Combined with the Trick Flow 6.25-inch-long pushrods, the valvetrain geometry looked to be dead on. We ended up having to shim the rocker arms using the Ford Racing shim kit to get the proper lifter preload to close the valves all of the way. A slightly longer pushrod may have helped, but we had the shims lying around and they were a quick fix.
Our Capri still had the stock...
Our Capri still had the stock clutch in it-remarkable considering it never slipped during any of our drag testing, not to mention the fact that it has some 120,000 miles on it. With the hot engine combination we were using, we opted to upgrade to this Ram HDX clutch and billet-steel flywheel that we got from Americanmuscle.com. Make sure you follow Ram's break-in procedure before you let the clutch fly.
When you do a clutch job,...
When you do a clutch job, it's always a good idea to pop for a new pilot bearing for the back of the crankshaft. Once that was installed, the Ram billet steel flywheel was mounted next using some thread locker on the bolt threads.
Having previously launched the car at 5,500 rpm, we thought it wise to back the launch rpm down a bit to compensate for the cold track. Baldwin held the throttle at 4,500 rpm and popped the clutch on the third amber. The tires spun badly and when he dialed up Second gear, Baldwin was put on "shift waiting." Once he found Second gear, he pulled the engine up to 5,800 rpm (a feat that wasn't possible before the new heads due to valve float) and shifted the remaining gears to cross the finish line in 15.47 seconds at 104.35 mph. The heinous 3.19-second 60-foot time told the whole story. Baldwin's second pass was much better.
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.
The Ram clutch setup was next....
The Ram clutch setup was next. The flywheel did not come with dowel pins, but luckily we were able to pirate some from another project. The factory clutch bolts were the wrong pitch thread as well, and we had to drop by the hardware store for some metric fasteners. If you're ordering head bolts from Summit Racing, you can order these at the same time.
At this point, we handed the keys to the rookie, Chris Crosby, who runs low 12s with his naturally aspirated heads/cam/intake Fox-body coupe. Crosby specified 12 psi of air in the tires and attempted a 4,000-rpm launch, to which the Capri responded with bad wheel spin. Crosby aborted the run and wheeled around for another go. This time, a 3,000-rpm launch resulted in mild wheel spin and a 1.88-second short time, followed by a 12.80 run at 107.97 mph.
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.
With the cold weather and...
With the cold weather and track surface, we were forced to launch the car at a somewhat soft 3,000 rpm rather than 5,500, which worked at our last track outing. Because of this, our 60-foot times were subsequently off. Nevertheless, we still dropped a second off our best elapsed time, but there is more in the car, so we'll be addressing the suspension next.
For run seven, Baldwin jumped back in the hot seat after swapping out the Holley's 65 jets for a set of 70s. We opted to make a big change in the sizing to see a good change one way or another. As it turns out, that plan didn't exactly work. Baldwin let the clutch fly at 3,500 rpm and the Capri responded with a 1.88-second 60-foot time. It crossed the stripe in 12.84 seconds at 107.53 mph. At the driver's request, we ditched the paper air filter element and air cleaner, and headed back to the starting line.
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.
Making jet changes to the...
Making jet changes to the 4160-series Holley carburetor is pretty easy. Place a container or numerous rags beneath the front bowl to catch the extra fuel that comes out after you remove the four front bolts; then the jets turn out with a stubby, flat blade screwdriver. In a pinch, a penny will work too.
Holley provided us with a...
Holley provided us with a jet change set so that we could fine-tune our combination. We only had time to make one change, and we pulled the 65s that were in the carb and replaced them with 70s. We didn't really see any change in performance despite such a large numerical change in jet size. Pulling the air filter didn't do anything either, so we will look into a possible fuel supply issue as the reason for the lack of change.
Rather than use a typical...
Rather than use a typical parts store tire pressure gauge, we contacted the folks at Moroso to get one of their Pro Series tire pressure gauges (PN 89560), as well as some Race Write marker paint for the track. The Race Write stuff works great, wipes off easily, and even works when its 40 degrees outside.