Best Tool For Cylinder Head Work
Article by Mark Trotta
For porting or port matching, you need a strong, reliable grinding tool with speed control. Whether you're working with cast iron or aluminum cylinder heads, an electric rotary grinder will give you the easiest, fastest results.
In contrast, an air-powered die grinder has very little torque at low speeds, and spins much too fast for accurate porting.
Rotary Tool with Flex Shaft
My choice was a Foredom TX series, which I've used on both motorcycle and automotive heads. For those unfamiliar, Foredom is a U.S. owned and operated company, and offer a complete line of industrial-grade rotary tools, handpieces, and attachments.
Pendant Motor
The TX motor is a separate, hanging unit, coupled to a speed control (either floor or bench mounted) and a 39" flex hose.
When in use, I'll hang the motor on a hook on a workbench shelf.
The speed control can be either bench or floor mounted.
Mine is an earlier model that has a dial-type speed control. I keep it at the base of my bench-mounted drill press.
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Dremel vs Foredom
A Dremel runs up to 35,000 RPM, while a Foredom motor runs between 15,000 and 18,000 RPM. What that means is, a Dremel will tear up disposable's quicker and make more noise.
A Dremel is more suited for wood, glass, or jewelry than metal. My wife has one in her craft shed and uses it for ceramics.
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Pocket Porting
Automotive head porting refers to modifying cylinder heads to achieve more volume or less restricted flow. At a minimum, this would be smoothing out the radius of the valve pockets.
CAUTION: A well-intentioned amateur can easily ruin a good cylinder by removing too much metal.
Port Matching
Port matching is correcting misalignments between intake manifold and cylinder head ports. A common way to port match is, take a felt-tip marker (or machinist dye) and trace the ports on the gaskets, then slowly remove the excess metal, just enough so it blends in. When done, air/fuel mixture will have a smoother transition from intake to heads.
Removing Casting Flash
Most DIYers are comfortable with grinding off casting flash left from the manufacturing process. All you're doing is removing unwanted metal and smoothing rough surfaces.
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Other Uses
Whatever you originally purchase an electric rotary tool for, you will find other uses for it, such as cutting, deburring, grinding, and polishing. They also work well removing rust and corrosion from hard to get places.
Removing rust from manifold ports with a wire wheel attachment.
Switching attachments to remove rust from combustion chamber.
Electric rotary grinders also make quick work of grinding down weld repairs.
Smoothing down a weld on aluminum with an 80 grit sanding drum.
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Attachments
There are dozens of different types of burrs, bits, and buffs that fit onto the handpiece.
Best Cutting Burr for Cast Iron
For grinding and polishing cast iron, double-cut carbide burrs work best.
These are considerably more expensive than regular steel burrs, but last much longer.
Best Cutting Burr For Aluminum
A double-cut burr will 'gum up' on aluminum.
A single-cut burr is best for aluminum.
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Attachments for electric or air rotary tools may also be fitted to angle or straight die grinders and air rotary tools.
Purchasing a Carbide Burr Set will give you more for the money.
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Handpiece Options
Foredom offers handpieces in many shapes and sizes. All are lightweight and made in USA.
The one I have is a 44T Handpiece, which fits comfortably in my large (XL glove) hand.
When purchased, 3/32", 1/8" and 1/4" collets were included, but I only use the 1/4" collet. Also included were pin and wrench for changing accessories.
Changing Attachments
To loosen/tighten the collet to change bits, a pin is inserted into the hand piece, then the nut can be loosened/tightened with a small wrench.
Some people think this is too much trouble, but it's never bothered me any.
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Shop: Foredom TX Motor with Speed Control and Flexible Shaft
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Beware of Counterfeits
Counterfeit Foredom rotary motors have been offered on several online sites. They can be difficult to recognize, as they usually come with an authentic-looking label and a serial number on the motor. If the advertised price is much lower than everywhere else, beware!
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Notes and Misc
You MUST use a speed controller of some type. Full speed is dangerous.
Protect your hands from cuts and abrasions - wear gloves.
Wear a face shield or safety glasses with side-protectors.
For those of you that regularly use air tools, an electric rotary grinder will be a quiet relief. The only sound it makes is a low-pitched whir.
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