It’s the little things that add up and in this case, we’re talking about port matching the intake manifold to a pair of cylinder heads. If you recall, we recently put together a potent, Dart-based, 434ci small-block (“The Bigger Mouse,” Mar. ’12). The whole point of this build was to showcase how a well-thought-out combination could produce big-block–like torque and be perfectly streetable with a thirst for cheap petrol.
During the initial assembly, we left all of the components in its out-of-the-box configuration and decided not to port match the single-plane manifold to the Dart Pro 1 CNC-ported 227 cylinder heads. Was it detrimental to performance? Given the 542 lb-ft and 552hp results, it’s safe to say no and our big-inch Mouse performed rather admirably.
This time around, we wanted to apply all the finishing touches to help create a more efficient powerplant. First, let’s be honest and squash any potential debates; port matching will not give you a significant gain in horsepower.
Think of it this way; smoothing the air transition from the intake to the cylinder heads offers consistent airspeed and flow. The smaller the runner the faster the air, however, when it hits the larger port, it tends to slow down the airspeed and can ruin the fuel mixture. This can also cause potential tuning issues and more importantly, a lack of peak horsepower.
Again, we’re not talking huge gains, but it all helps to maximize your combination. If you have the tools, this is something that can be handled in the garage. If you prefer to farm out the work, then expect to shell out $150 to get the job done with a competent machinist. Follow along as Rocco Acerrio of A.R.E. Performance & Machine shows the ins and outs of port matching.
[01] Out of the box, the intake...
[01] Out of the box, the intake manifold is considerably smaller than the 1206 Fel-Pro gasket.
[02] Here are the tools needed...
[02] Here are the tools needed for port matching: Red Dykem is used with a scribing tool to show where the port needs to be; several carbide bits in different shapes and sizes for roughing the ports; cartridge rolls in different grits for a smoother surface finish; and a high-torque long-reach air grinder.
[03] We started by brushing...
[03] We started by brushing the Dykem onto the manifold. Dykem dries quickly and allows the scribe lines to show better on the aluminum. Note: You have a choice of red or blue and it’s only a personal preference on which one to use.
[04] Using a piece of stainless...
[04] Using a piece of stainless rod, Rocco prefers to scribe the gasket ports through the manifold, which actually simulates the gasket’s exact location when the intake is bolted down.
[05] After extending the scribe...
[05] After extending the scribe through the manifold, pressure is applied back up into the intake face. From there, the scribe is slid both vertically and horizontally, appropriately matching the intake port of the cylinder head. With all the ports marked, the intake manifold is then removed and a straightedge is used to finish laying out the guidelines.
[06] The right port has been...
[06] The right port has been roughed up with a carbide bit, and you can see the difference on the factory-casted port on the left.
[07] The final touch is to...
[07] The final touch is to use the cartridge rolls to smooth out the ports and match them up to the scribed lines. Note: A typical port match job will go 11/2 to 2 inches into the runner in order to ensure a smooth transition.
[08] With the job complete,...
[08] With the job complete, a bead of black silicon was added to the end rails with the manifold put back into place. If you’re doing this with the engine in the car, be sure to wait approximately a half hour before firing it up.
[09] For final fitment, all...
[09] For final fitment, all bolts were torqued to 25 ft-lb.