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Intake Manifold, Carburetor Combination, and Ignition System Upgrade - 4 Barrels Of 5.0L Fun Part 2
Our '85 Capri Gets An Intake Manifold And Carburetor Combination, Along With A New Ignition System.
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.
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.
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.