Guide and Seat Equipment
By Larry Carley
Cylinder head work has been and should continue to be a profit center for engine builders. Heads almost always require guide and seat work to restore compression and oil control. This includes drilling, reaming and replacing valve guides, removing worn, loose or damaged valve seats, cutting new seat counterbores, and machining valve seats. For performance work, it may also be necessary to trim guide bosses and spring seats, and realign or reposition guides and seats within the head. All of these jobs require up-to-date equipment that can handle today's multi-valve cylinder, and do it quickly, accurately and profitably.
Guide and seat machines have not changed a great deal in recent years. Many machines are quite similar in both appearance and operation. But there have been steady improvements and refinements in tooling and fixturing, and a closer look will reveal differences in the type of pilot system used ("live" pilot versus "fixed" pilot), the type of fixturing used (clamping and leveling systems, ease of setup, and the ability to handle large and small cylinder heads), the operating features of the machine head (how far it can tilt, the diameter and rigidity of the spindle shaft, the type of drive system, how far the power head can travel vertically as well as back and forth), differences in the size of the work table, how much storage is provided for tooling, and finally differences in the tooling (ease of setup, ability to resharpen quickly and easily, durability and cost).
Included with this article are brief profiles of valve and seat machine suppliers so you can shop and compare equipment. For additional information, consult Engine Builder magazine's 2004 Engine Builders Buyers Guide or access the information at www.engine-builder.com.
Most valve seat and guide machines today come with an air float head that makes head repositioning quick and easy. A tilting head is handy for quickly aligning the spindle with the guide in the cylinder head. Pre-shaped carbide cutters that cut all three valve angles in one step eliminate the need for setting separate blades and maintain better consistency of the width, size and location of the cuts.
Some of the newer machines are available with computer numeric controls (CNC) for high volume production shops that want to automate certain steps in the machining process to save time and improve consistency. Other optional features may include things like a digital depth gauge, digital setting fixture for adjusting seat cutters to an exact size, or an electronic level to make head leveling quicker and easier.
In recent years, there has also been a trend toward "multi-purpose" machining centers. These "do-it-all" machines can typically handle boring and surfacing as well as guide and seat work, making them well-suited for smaller shops with limited floor space or those who don't want to buy a separate piece of equipment for each different machining operation in the shop. A multi-purpose machine is ideal for a low volume shop, and provides a great deal of flexibility as well as cost savings. Most of these machines can be quickly converted from one type of operation to another within a matter of minutes. Even so, in a high volume shop where every minute counts and work has to flow rapidly from one operation to the next, a dedicated valve seat and guide machine and a separate boring/surfacing machine may be a better choice.
If you're in the market for a new guide and seat machine, or a multi-purpose machining center that can also handle valve and seat work, there are a number of equipment suppliers who can help you choose a machine that will match your needs. When discussing your needs with an equipment supplier, consider the following questions:
What type of work are you doing now? How does that match up with the features and capabilities of the supplier's guide and seat machine?
If you're only doing passenger car/light truck engines and have no intention of getting into heavy-duty diesels, you obviously don't need a machine built to hold Cummins or Caterpillar heads. On the other hand, if you do virtually anything that comes in the door from small engines to big, you'll want a machine that's flexible enough to handle the broadest possible range of cylinder heads.
Are you doing mostly stock work, performance engine building or both?
If you're doing mostly stock engine work and need to cycle heads quickly to maintain your shop's productivity and profitability, speed is an essential feature to look for in new equipment. That means fixturing and tooling that is quick and easy to set up, possibly live pilot tooling to speed up the guide and seat work, and maybe even automated controls.
On the other hand, if you're doing mostly performance work, essential features to look for would be the highest possible precision and the ability to accurately control and locate guides and seats in the cylinder head. You also want a machine that can handle aftermarket performance heads as well as stock heads.
Why do you want a new guide and seat machine, or a multi-purpose machining center?
Do you need to upgrade old, outdated, worn-out equipment?
Are you trying to grow your business and need a new machine or an additional machine to do more head work?
Do you need equipment that can handle bigger/smaller heads, or that can do multiple tasks?
Do you need to automate certain processes as much as possible so you can make better use of your available manpower?
How you answer these questions should help you decide what kind of seat and guide machine best suits your needs.
Are there floor space limitations and/or special workflow requirements within your shop?
If you're cramped for floor space, a multi-purpose machining center might give you the elbow room you need by combining head work with surfacing and boring.
How much does the equipment cost? How much is it worth?
Though price may be the first question you ask, the cost of the equipment itself may be the last thing you should consider because what the equipment can do for you is just as important as its final price tag. A good machine that does everything you want it to do is far more important than buying a less capable machine that may cost a few thousand dollars less.
The price of a fully equipped guide and seat machine typically starts at around $24,000 and can go as high as $70,000 to $80,000 depending on how many bells and whistles you want. Multi-purpose machining centers may range from $16,000 up to $35,000 or more, depending on tooling and features.
Obviously, you should buy a machine that will make you money (unless machining valve guides and seats is your hobby) and give you a solid return on your investment. But don't just look at the cost of the equipment itself. Consider what it can do to improve quality, boost productivity and overall profitability in your shop.
Buying a machine that allows you to do a wider variety of heads can open up new markets and allow you to expand your business. Reducing comebacks by improving quality can slash warranty costs and enhance your reputation. Being able to machine heads in less time may eliminate a bottleneck and allow jobs to progress more smoothly through the shop.
Before you buy, compare the features of competitive equipment and ask the supplier to explain why their machine is better, faster or whatever than their competitors.
Finally, don't buy before you try. Nothing beats spending some time with a machine to see if it's right for you. If possible, you should also ask for the names of some other shop owners who have purchased similar equipment. Call them up and ask them how satisfied they are with their equipment, and whether or not they'd recommend it to you.
CWT's "Pro-1058" machining center is a multi-purpose machine that can do guide and seat work as well as resurfacing, line boring and cylinder boring. It is available in manual or CNC configuration.
The CNC version offers "closed loop positioning" that allows the machine to reposition and repeat repetitive machining operations to save operator time. The air float head is fully protected from machining debris, and can accept live or fixed pilot tooling.
The machine also features a quick level table, and can handle most passenger car blocks including big block Chevys.
Winona Van Norman
The VSG4720 Cylinder Head Machining Center available from Winona Van Norman is designed for precision, speed and versatility, says the company. With a combination of features and an expansive working range, it can handle a wide variety of operations.
- Single-blade three-angle tooling gives fast, easy and precise set-up. The three single-blade angle bits ensure accuracy, exact angles and precision seat width.
- Fixed pilots require less clearance than rotating pilots to revolve within the guide.
- The airfloat workhead moves, centers and clamps easily and precisely for easy alignment, giving the operator pin point control.
- Capable of handling heads up to 47.2? long - enough capacity for a 3406 Caterpillar - the VSG4720 also has 20.3? of vertical clearance. It can accept the "BlokTru" fixture to machine lifter bores and do seat and guide work on flathead V8s.
- Use the tooling you already have or standard aftermarket tooling. Special adapters aren't needed.
PETERSON MACHINE TOOL INC.
Council Grove, KS
Peterson has a couple of different valve and guide machines. The "TCMV25" features a rugged, heavy-duty column that supports the powerhead without vibration or deflection. The 360 degree rotation air table allows easy, precise positioning of heads for cutting seat angles with the tri-cut 3-angle tooling. The machine uses a dead pilot with standard #3 Morse taper adapter for quick tool changes. Options include a power column and additional tooling.
The "ASV/A" valve guide and seat machine has an air balanced spindle, and a pneumatic tool change for rapid toolhead changes between operations. The positive stop alignment and air clamping of the fixture makes setup on four valve heads quick and easy. Standard features also include a 360-degree roll-over fixture and dial depth indicator.
Rottler has two valve guide and seat machines, the "SGF7" and "SGF8." Both machines feature a patented fixed pilot system that is said to be faster to set up than traditional fixed pilot tooling.
Both machines have a tilting (up to 15 degrees) air float workhead with foot pedal control for hand free air clamping, a universal 360-degree roll-over fixture, and quick change tool retention system. A large diameter variable speed spindle provides both accuracy and control.
A depth indicator shows the operator exactly how much metal has been removed from the seat to help assure consistent seat depth. Increased spindle to table height allows extra long reamers and drill tooling to be used on different heads. The SGF7 can handle passenger car/light truck heads up to 28 inches in length, while the larger SGF8 can accommodate diesel heads up to 44 inches in length.
Stone Mtn., GA
Serdi offers a broad lineup of specialized valve guide and seat machines including the following:
- "SERDI Profil" is a single point cutting system for achieving high concentricity on any type of seat material.
- "SERDI 7.0" is an automatic machine for head work on small to medium-sized engines. The machine features a tool changer that allows inlet and exhaust valve guides and seats to be machined in one working cycle, as well as a specific fixture for clamping heads.
- "SERDI 6.0" is a dedicated automatic machining system for production processing of small to medium size heads.
- "SERDI 5.0" is the world's first PC driven valve guide and seat machine for small to medium size heads.
- "SERDI 4.0 POWER" is a manual machine with air floated table bars.
- "Serdi 100 HD" is a heavy-duty seat and guide machine with an extremely rigid main frame, with a workhead designed for low speed machining of big diameter seats. Comes with air controlled table bars.
- "Serdi 3.0 Lg" which features a triple air flotation workhead, wide upper bed and long table bars.
- "Serdi 2.0" is for automotive and diesel applications.
- "Serdi 1.1" is for motorcycle and automotive multi-valve heads, and comes with a triple air flotation workhead.
- "Serdi 1.0 AD" is designed for small motorcycle and automotive multi-valve heads.
SUNNEN PRODUCTS CO.
St. Louis, MO
Sunnen currently offers four different valve seat and guide machines:
"VGS-20" can handle everything from subcompacts to big diesels (up to 48 inches in length). The machine has an air float head and adjustable speeds for high concentricity and accuracy. Tooling is quick and easy to change.
"SGM-1500" has fixed pilot tooling and is said to provide valve seat concentricity of .001 inch or less per 1 inch of valve diameter. The machine has a large table that can handle passenger car heads up to big CAT 3406 heads. The bolt-down head fixture rotates 360 degrees and features quick release handles to eliminate play. The air-float spindle tilts up to 15 degrees so canted heads can be cut without tilting the head.
"Sunnen/DCM HMC-2500 SD" is a multi-purpose machining center that can do boring as well as guide and seat work. Operates with manual or automatic mode. Features a rigid quill lock, simple programmable controls, live or dead pilot seat cutting, and vacuum-lock air-float cradle.
"Sunnen/DCM HMC-3000 SD" is also a multi-purpose machining center that does block surfacing and boring as well as guide and seat work, performance porting and combustion chamber forming. It features CNC-like operation with a simple operator interface.
T & S MACHINES & TOOLS INC.
The newest valve guide and seat machine from T & S is the "TS2000XL" which can accommodate heads 2 inches higher and 10 inches longer than the "TS2000" machine.
The new machine has dual fixtures so it can handle two heads at once for more consistent valve seat height. Both machines use a ball-drive dead pilot system for high concentricity. A tilting head allows easily alignment of the spindle to the head.
Electronic angle finder allows precise alignment between quill and work piece, up to 15 degree tilt with .01 degree resolution. Maximum cylinder head length in the rollover is 48 inches (58 inches in XL model).