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Decongestion

Port matching your intake manifold

Nearly every performance car guy has made an intake swap in the quest for better breathing and improved performance. The problem is that after spending a couple of hours making the swap, sometimes little if any gain is achieved. You scratch your head, yell at the dog, and are downright mad about investing your good time and money for relatively no performance gain. You wonder why.

Mismatch

The answer: the port openings at the end of the runners on the intake manifold do not match up to the port openings on the cylinder head. The resulting mismatch causes congestion of the air/fuel mixture as it travels toward the intake valve. This snarl-up slows down the velocity of the airflow.

Well, with a little planning, the proper tools, and some patience, the average do-it-yourselfer can clear up this congestion by port matching (gasket match) the intake manifold. This port/gasket matching is just what the doctor ordered to enable your engine to better breath!

For our project, we decided to go with a Holley Street Dominator intake manifold for a Pontiac. This manifold has been out of production for the Pontiac for many years and is a great swap meet find. We were lucky to find a virgin intake ready to be properly fit to our freshly done cylinder heads that were "street ported" to Pontiac RAIII intake port dimensions.

Planning

A big part of any project is proper planning and the courage to proceed. Hopefully, as a DIYer you know your limits. If you are good with your hands, have carved or sculpted, you will be comfortable with the techniques described. This is a "big bang for your buck" project because it is "your" time, not a professional porter's time that could cost you upwards of $250.

First, you will need to gather the parts; the intake and a set of gaskets that will be used as a template. A scribe and some Dykem layout fluid (machinist's bluing) are needed so you can scribe the layout on your intake. A felt-tip marker can also be used to mark the surface; but, as you can see, the Dykem does a much better job. Importantly, you will need to layout an area in your workshop where you can perform the work. A stable bench to which you can affix the manifold when porting is a must. Make certain to cover the surrounding area because metal filings and dust can get everywhere. Finally, you will need to assemble the required tools.

Tools

The best tools for home porting are either an air operated die grinder or an electric die grinder, each with a 1/4-inch collect. My preference is an air operated die grinder, as it offers far greater rpm control through the regulating air pressure. If you take the electric die grinder route, make certain the grinder's maximum speed is 18,000-20,000 rpm. Too much rpm and the grinder can get away from you. You want to have complete control over your tool bits when working on the ports.

Yes, you will need a small variety of carbide bits. The best shape for all-around use is the conical or football shaped bit. Make sure that if you are working on aluminum you purchase an "open pitch" bit to avoid clogging. Expect to pay upwards of $30 for a long shank quality carbide bit. There are also economical kits available from Eastwood Company and Standard Abrasives that include a variety of abrasive stones, sanding rolls and mandrels. You can also purchase these tools at your local industrial hardware store.

Of course, if you are using an air-die grinder you will need an air compressor. Most available air compressors that can maintain 40 psi will be up to the task. Again, keeping the air pressure regulated enables better control of your porting equipment.

Safety

It cannot be stressed enough the need for proper safety equipment. You are going to be grinding on metal and shavings will be flying. You must wear safety glasses, goggles or a safety shield. A flying metal chip can easily penetrate your eye and this is way down on the fun quotient. A disposable breathing mask is recommended to keep you from getting congested. It is also a good idea to get a good set of gloves and some ear protection.

Patience, Practice

You will be using power tools. As you have heard countless times, "Speed Kills"—and particularly when porting aluminum. Take your time. If you have not used a die grinder before, you will want to practice. Likely, you will not have a spare manifold lying around but fear not—use the one you will be porting.

There are plenty of areas, like the casting lines on the exterior of the manifold that you can sweeten up. This will give you a feel for the tool. Feel is the word here. You do not want too press hard. You want to let the tool do the work. Don't try to remove too much material at a once. Continually move the tool in an up and down and circular motion over the surface you are shaping. You will be surprised at how this constant movement will enable you to shape straight walls. Shaping is a key concept here. You are not cutting on this manifold; you are shaping the runner and port dimensions to match the gasket opening.

Follow these easy steps (see photos) and in no time your engine will be breathing freely and roaring through the gears.