Summit Racing sells carburetor...
Summit Racing sells carburetor and air cleaner combos, as well as carb, air cleaner, and intake combinations. We chose the latter, and included in the value pack was this Summit open element air cleaner and Holley 600-cfm vacuum secondary carb with electric choke.
Last month we started a short build series on an '85 Mercury Capri; this month we're continuing with an intake manifold and ignition system swap. To bring you up to speed, we took what was essentially a stock 5.0L Capri and updated the brakes and rear axle with later-model Fox-body components.
As purchased, the Capri ran a sluggish 15.44 at 89.79 mph. After a few tweaks and the addition of Weld Racing Draglite wheels and Toyo drag tires, we chopped at the elapsed time tree until it read 14.26 at 94.10 mph. In this issue, we weren't lucky enough to make such impressive headway in reducing our quarter-mile elapsed times. For the most part, the faster you go, the harder it is to improve.
Coming right off the track with our impressive 14.26 performance, we popped the hood and bolted on a Holley 600-cfm carburetor, which was part of the Summit Racing Value Pack that we ordered. We felt that the 750-cfm Edelbrock piece that was on the car was simply too large for a little 302ci engine, and wanted to see what a more appropriately sized fuel mixer would do. To that end, we then installed the Holley, along with a 1-inch spacer that we needed to make the carburetor clear the stock intake manifold.
With the vacuum port coming...
With the vacuum port coming right out of the back of the carburetor, we couldn't bolt the Holley up to the stock manifold because it would hit the factory EGR plate. We borrowed this 1-inch plate from Mopar Muscle Tech Editor Dave Young so we could give the Holley a try while using the stock intake manifold.
Out of the box, the Holley produced a 14.33/93.94-mph run with a 1.94 60-foot time. Our next pass started with a 1.93-second short time, followed by a 14.14 e.t. at 94.96 mph. We made another pass after that, which resulted in a 14.37 at 93.79 mph (1.98 60-foot). We expected a bit more improvement in elapsed time from the carburetor, but mph did pick up slightly, so there may be something else hindering the progress.
At this point, we felt brave and tried to perform a trackside intake manifold swap, but our efforts were thwarted upon start up as we sprung a leak at the back of the intake manifold. We didn't have another set of gaskets, and more importantly, the track was about to close, so the intake test had to wait for another day. Best laid plans and so on and so forth.
The leak turned out to be nothing more than a lack of proper cleaning at the cylinder head's rear water port. So we reinstalled the Weiand Street Warrior dual-plane intake manifold, along with the Holley 600, and headed back to the track. We also took the time to wire in our new Performance Distributors ignition system so we could easily perform a trackside swap of the ignition components.
Installation of the carburetor...
Installation of the carburetor was otherwise pretty easy. First, choose which throttle cable ball is the right one for your application; then bolt on the carburetor.
Seeing that the spark plug wires were still original, we thought it was time to update the ignition components. At some point, someone had changed the spark plugs, but everything else was as Ford built it. Performance Distributors delivered a set of its hot Livewires, billet aluminum wire looms, an Inferno 2 ignition coil, and a Dyna-Mod to replace the factory Duraspark setup.
Our first run of the evening netted a 14.48 at 95.98 mph, this despite a wimpy 2.15-second short time. Our driver, George "The Greek" Xenos launched the Capri at 3,000 rpm and shifted at 4,700 rpm, just like we had at our previous test session. His second pass of the evening started with a slightly quicker 1.98 60-foot time, which translated into a 14.30 at 95.80 mph.
The Greek reported that the car was still accelerating hard at 4,700, so we raised the shift point to 5,000 for the next run. The higher shift point was the ticket as the Merc responded with a 14.12 at 96.32 mph, even with a slow 2.00 short time. Feeling there was a bit more in the car before we moved on to the ignition system, we made another hit and a quicker 1.96 60-foot time netted our first 13-second pass-a 13.98 at 97.05 mph. We opted to raise the shift point on the next pass and ran a 14.06 at 96.95 mph with a 1.96-second 60-foot time.
The Holley bolted right down...
The Holley bolted right down and we didn't touch the jetting.
Part of the Summit Racing...
Part of the Summit Racing Value Pack is this Weiand dual-plane Street Warrior intake manifold. It's a low-rise piece that features a square-bore mounting pad, and it's designed to work from Idle to 5,500 rpm.
After pulling the stock intake...
After pulling the stock intake manifold, we were able to see that the lifter valley was pretty clean given the year of the vehicle. Make sure you clean the head surfaces completely before laying down the new gaskets and intake manifold.
Here's a top shot comparing...
Here's a top shot comparing the Weiand intake (left) and the factory aluminum piece. Ford did a good job but we think the aftermarket piece will deliver better results. Not only do the runners take different paths, but the Weiand runners are larger in volume as well.
It helps to have an extra...
It helps to have an extra set of hands to install the intake manifold. Here Tony Gonyon assists George Xenos in planting the Street Warrior between the valve covers. Be sure to follow the intake-bolt pattern included in the instructions. Don't tighten the bolts past 22 lb-ft, otherwise you risk distorting the cylinder-head-to-block arrangement.
To match the vintage Boss...
To match the vintage Boss 302 valve covers that we are using, we called up Ford Racing Performance Parts and ordered this cast-aluminum air-cleaner assembly to match. Part number M-9600-L302 nets you a 13-inch air cleaner that retails for about $69.
Performance Distributors has...
Performance Distributors has been electrifying automobiles for years now, and the company knows the 5.0L Mustang very well. PD supplied us with a set of its Livewires, an Inferno 2 ignition coil, and one of the company's Dyna-Mod modules.
Truthfully, we expected a bit more from the intake manifold and carburetor combination, and while we did pick up 2 mph, we're thinking a jetting change may be in order. Unfortunately we didn't have any with us, so we moved on to the Performance Distributors Firepower ignition system. Lucky for the Greek, he got to play crew chief and driver while we took the photos.
The factory plug wires were disposed of quickly, and we ditched the spark plugs as well. PD specified wider plug gaps (0.050 to 0.055-inch) with its Inferno 2 coil and Livewires, so we opened up a fresh set of Autolite 25s, gapped them to 0.052, and screwed them in. We also plugged in the Dyna-Mod and coil connections. The 5.0L immediately sounded better and revved faster upon start up, but would this translate to quicker elapsed times on the track?
Pulling out of the burnout box and up to the line, Xenos pulled the engine rpm to 3,500 and let the clutch out. The first 60 feet passed in a scant 1.91 seconds and he shifted each gear at 5,200 rpm. The Capri tripped the top-end lights in 13.98 seconds at 97.05 mph. That's the first time we saw a 97-mph trap speed, and we wouldn't dip below that the rest of the evening. On the next run, the 60-foot rose to 1.95 seconds, and the quarter-mile time followed at 14.04 seconds at 97.03 mph. We followed this with three 14.0s, and a hard 4,000-rpm launch netted a 1.88 60-foot time, along with a 13.94 at 97.09 mph.
While the mods this time around did not make a significant leap in performance as on our first outing, they have put us solidly in the high-13 to low-14-second range at 97 mph-a 0.2-second reduction in elapsed time and 2 more mph. We'll get ourselves a box of jets for the next time out at the track and see if that might wake things up a bit. We also have a complete true-dual exhaust system that we're going to bolt up to replace the factory Y-pipe, headers and 2.25-inch exhaust. In addition, we've picked out a pair of high-performance cylinder heads and a hot camshaft to get our carbureted 5.0L thumping.
The Inferno 2 coil was mounted...
The Inferno 2 coil was mounted on the front of the driver-side shock tower. This helps limit the length of wiring we have to run, and the position seemed to work well for the '87-'93 cars.
We wired the Dyna-Mod and...
We wired the Dyna-Mod and coil in such a way that we can unplug the factory Duraspark ignition and coil at the track, and plug the Performance Distributors setup in without much effort.
We opted to mount the Dyna-Mod...
We opted to mount the Dyna-Mod high and dry up near the hood hinge.
With a prime spot right next...
With a prime spot right next to the staging lanes, George Xenos made quick work of the ignition swap at the strip.
In order for the Dyna-Mod...
In order for the Dyna-Mod to work, we had to wire in this heat sink resistor.
Follow the provided instruction...
Follow the provided instruction to wire up the Inferno 2 coil. It's a piece of cake.
The Livewires are designed...
The Livewires are designed to work with the much hotter coil, and they look a whole lot better than the factory leads.
Performance Distributors recommends...
Performance Distributors recommends opening the spark plug gap to 0.050-0.055 inch.
We checked the ignition timing...
We checked the ignition timing one last time before going out. After the intake, carburetor and ignition upgrades, we dropped 0.2 second and picked up 2 mph in the quarter-mile. We're going to throw some jetting changes at the Holley 600, and then we'll get a bit more serious with our four barrels of fun.