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Shops that do top quality work and have an establ...
The “UNIPILOT tooling system” from Rottler Manufa...
Keeping Valve Jobs Profitable
Cylinder head work accounts for a large percentage of the engine business in most machine shops: approximately one third of the gasoline engine rebuilding and repair business and 43 percent of the diesel engine rebuilding business according to a recent member survey conducted by the Engine Builder’s Association (AERA).
By Larry Carley
Okay, so head work accounts for a large percentage of your business. But is it as profitable as it should be or could be? Do you have a good handle on cylinder head related costs (parts, labor and cleaning)? Are the employees who are doing the head work competent and productive? Is your valve guide and seat machine and other shop equipment up-to-date, accurate and productive? Shortcomings in any of these areas can create bottlenecks that slow productivity and hurt the profitability of your cylinder head business.
Another aspect that affects profitability is the market you complete in and the type of customer who buy your cylinder head rebuilding services, custom work or finished heads. If you’re trying to compete with the lowest cost provider in your area, good luck because that business model seldom works for long. What you don’t make on individual jobs you can’t make up in volume.
Cutting your price 20 to 25 percent to attract more potential customers doesn’t mean your sales will automatically increase 25 percent. You may pick up some incremental business, but probably not enough of an increase in sales to offset the profits you gave up by slashing your prices.
Shops that do top quality work and have an established reputation are always in demand and can usually justify higher prices. Consequently, if your shop is the top dog in your market area your prices should reflect that position. Don’t waste your time competing with your low cost competitors.
One of the keys to establishing yourself as the best source for cylinder head work is to always deliver the best possible quality to your customers. Use high quality parts, not the cheapest parts you can find. Invest the time and effort into the finished product that it takes to do the job right. Don’t cut corners. Pay your skilled employees what they are worth and invest in the kind of shop equipment that is capable of delivering the highest quality work.
The Typical Valve Job
There is no such thing as a typical valve job. Every job is unique. When a cylinder head comes in for a valve job, it is usually a high mileage head that may have one or more worn or burned valves, worn or loose valve seats, and worn or loose valve guides.
It might have one or more bent valves if it’s an OHC head and the engine experienced a cam belt failure. The head might have weak valve springs that have reached the end of the road. You never know for sure what a head might need until you have disassembled and inspected everything.
Cracks are a common problem you always have to watch out for. Crack detection requires penetrating dye on aluminum heads, magnetic particle inspection on cast iron heads, and possibly submerging the head in a water tank and pressurizing it to check for hidden cracks or porosity leaks.
If a head is cracked, you have to decide whether it makes more sense to repair it or replace it.
Cracks that are small and can be pinned or welded at a reasonable cost means the head may be more profitable to repair rather than replace (especially if the casting is expensive, difficult or impossible to find). On the other hand, if the head is a relatively inexpensive casting that can be easily and affordably replaced, why invest time and labor into trying to fix a cracked head if replacing it is easier, faster or less costly?
These are judgment calls that affect your bottom line every day, so you have to keep yourself informed about the latest core market prices, the cost of new aftermarket and original equipment castings, and how much shop labor may be required to fix or recondition a damaged or cracked head.
Some engine builders pride themselves in their ability to fix almost any kind of head (cast iron or aluminum) or any type of head damage. This can be a significant market advantage if you have the proper equipment and know-how. If you can repair heads that others reject or think are impossible to fix, you have a major advantage over your competitors.
If a cracked cylinder head can be repaired for less than what it would cost to replace it, repairing it usually makes sense (assuming the repairs are successful and there are no “do overs” required!). On the other hand, if the damage is such that you would have to invest a lot of labor in the head (or the repair would be risky), replacing it would probably make the most sense.
Of course, there are always exceptions. Your customer might not want to risk a repaired head if his original head is badly cracked. He may insist on a new casting. Or, a customer may want you to save his original head no matter what the cost.
This might be the case if the head is off an antique motor or a vintage muscle car engine and he wants to keep everything original with matching casting numbers. The bottom line here is that the customer is usually right especially if he agrees to pay what ever it costs to give him what he wants!
Time Is Money
Time is money so in some cases it may be more profitable to replace rather than repair or reclaim head castings and other parts if they are worn or damaged. You have to look at the total cost of the job as well as the time you may have to invest in repairing, reconditioning and remachining the casting and valves.
You can repair and recondition damaged heads and worn valves to save the cost of having to replace them. Or, you can replace a bad casting and worn valves with new ones to save the time and effort it would take to repair or recondition these parts. The time saved on labor should allow you to complete the job more quickly, which in theory should allow you to complete more total jobs in the same amount of time.
This works best when customers are being quoted a total package price for a finished valve job rather than an itemized labor bill for each individual process that goes into the head. Parts are usually itemized and billed extra unless you are automatically including new valves, springs, etc. in a package price.
On the other hand, if you feel the only way to make money is to bill a lot of labor and itemize each step in the process (cleaning, disassembly/reassembly, crack inspection, recondition or replace valve guides, recondition or replace valve seats, recondition valves, resurface head, etc.), then go for it. Some customers would rather be billed this way than given a flat package labor price.
Regardless of how you charge for your head work labor, what your hourly shop rate is, or what you charge for a valve job, the objective is to be as productive as possible and as profitable as possible.
According to one large national remanufacturer, fixed and dead pilots have proven over the years to give more accurate concentricity
compared to live pilots, mainly because live pilots have clearance between the pilot and the valve guide.
The “UNIPILOT tooling system” from Rottler Manufacturing allows the carbide centralizing pilot to work like a live pilot it stays in the spindle while moving from valve guide to valve guide but at the same time has a fixed pilot design to give improved concentricity.
The section of the pilot that fits into the valve guide is straight/parallel but it has a tapered upper area which is spring loaded and fixes in the valve guide while centering to eliminate any clearance between the pilot and valve guide. After cutting the valve seat, when the spindle lifts up automatically, the Unipilot remains in the spindle and is lifted at the same time ready to float over the head gasket fire decks and ready to enter the next valve guide.
On a manual machine, the vertical travel of the spindle is controlled by the operator by turning the steering wheel on the front of the workhead. With a taper on its lower end, the pilot is easily inserted into the valve guide. As the spindle is moved downwards by turning the steering wheel, the spring-loaded Unipilot is able to resist and, as the spring pressure increases, guides the tapered section into the valve guide. The complete pilot is then able to travel into the valve guide with rapid feed rate to the start seat cutting height.
At this position, the pilot is fixed inside the valve guide as its upper tapered section is in contact with the inside bore of the valve guide. At this stage, the operator waits for 2-3 seconds while the final centering of the unit and workhead takes place, and then releases the foot pedal and the workhead clamps rigidly, ready for seat cutting. The operator selects spindle rpm and starts the spindle rotation then starts cutting the valve seat by slowly turning the steering wheel. The depth measuring gauge is set, the fine down feed system is engaged and the final depth of the valve seat is then cut to its most accurate dimension.
Once the valve seat is fully cut and the depth gauge is set to zero, the operator turns the handwheel until the lower end of the pilot clears the cylinder head, presses the foot pedal to release and float the workhead and then repeats the operation.
On automatic machines the operator moves the floating workhead over the valve guide and touches the down feed button until the tapered part of the
Unipilot enters the valve guide. The machine’s CNC control then takes over, completes the entire seat cutting operation, and returns to the top, ready to cut the next valve seat.
Valves, Seats, Guides And Springs
Reconditioning versus replacing parts such as valves, seats, guides and springs is something else you need to consider when doing valve work. There are a variety of repair options from which you can choose. Some shops automatically replace high mileage exhaust valves whether they are burned or not to reduce the risk of valve failure later on. Installing new valves also saves the time of having to grind and reface the old valves.
Used valves can often be reconditioned if they are not too badly worn, bent, damaged or cracked. Worn stems can be ground and/or replated so they can be fitted to new guides or guide liners to restore normal stem-to-guide clearances. You can recondition the valves yourself if you have the proper equipment, or you can buy reconditioned valves from aftermarket suppliers who specialize in this type of work.
Some valves, especially heat resistant cobalt alloy Stellite exhaust valves, can be very expensive to replace. In some applications (like heavy-duty diesels), replacement is usually a requirement for reliability. New valves will likely be necessary if the cylinder head is going on a performance engine.
New valves may also be required for late model engine applications where the customer wants the same kind of durability as the original valves (150,000 to 200,000 or more miles). The budget 350 Chevy customer might not expect such durability, but if they are willing to pay for it you should offer it as an upgrade option.
Valve seats are seldom replaced unless they have to because they are loose, worn, cracked or damaged. A hard, wear resistance valve seat is required for durability, especially in high heat applications like performance engines and diesels. If you have to replace valve seats, don’t try to boost your profitability by sacrificing reliability and installing the cheapest cast iron low alloy seats you can find. Replace the seats with ones that are the same or better as the original seats.
Relatively cheap valve seats from China, India and Korea have flooded the U.S. market in recent years. Many of these seats sell for half or less the price of quality valve seats. But people are learning the hard way that you get what you pay for. The low alloy cast iron seats that seem like such a bargain often don’t hold up, and that can come back and bite you.
Nothing will hurt your business and your reputation more than warranty problems caused by using poor quality parts. Customers who have been burned will likely take their business elsewhere next time they need valve work.
Valve guides are usually worn, so the repair options include knocking out the old guides and replacing them with new ones, reaming out the original guides (integral or replaceable) and installing some type of valve guide liner to restore the ID dimensions, or reaming out the original guides to accommodate new valves with oversized valve stems (a good option if you are replacing the valves anyway).
To realize the most profitability in this area, you have to compare the relative time, tooling and material costs of replacing guides with new ones versus installing guide liners versus reaming out the guides and buying new valves with oversized stems.
Valve springs weaken with age, and by the time an engine has racked up 100,000 or more miles, the valve springs may be pretty tired. Shimming the springs can restore some of the lost pressure, but not reliability. High mileage springs are springs that may eventually fatigue, break and fail. So if durability is important, new valve springs are recommended. New valve springs are a must for performance engines, especially if you are installing a new camshaft and lifters.
Grinding and sanding are old technology when it comes to resurfacing today’s cylinder heads. Most late model heads can’t tolerate much roughness or distortion and must be dry milled to achieve the proper flatness and surface finish. The key to profitability here is having a resurfacing machine that is quick and accurate.
A milling machine has to be sturdy and strong so it can deliver a top notch finish. It doesn’t matter if you use carbide, CBN or PCD tool bits to resurface a head as long as you use the correct feed rate and speed, and the equipment is rigid enough to hold the cutter steady so the tool bit doesn’t lift or chatter when it makes in interrupted cut.
A converted grinder may be able to mill heads and blocks. But the spindles and table drives in many of these older machines cannot hold close enough tolerances to achieve a really smooth, flat finish. One equipment manufacturer said grinding and milling machines that are more than five years old are probably incapable of producing the kind of surface finishes that are required for today’s engines.
Most of the surfacing equipment that's being sold to shops today has been redesigned for high speed milling with CBN and PCD. The machines have been beefed up with more powerful motors, heavier castings, electrically-driven ball screw tables, and tighter assembly tolerances.
As a final suggestion, don’t try to squeeze too many jobs out of a set of cutting bits. They will dull with use, so to maintain good performance you need to check and replace your tooling bits as needed.