You may need to resurface your cylinder heads to improve the finish of the surface, restore flatness to the head. After welds or other repairs have been done to the cylinder head such as increasing the compression ration, the cylinder head may need resurfacing. Regardless of why you need to resurface the head, the important part of the process is getting it done quickly and correctly. If you make a mistake, it can cost you. You can not remove too much metal because you can not put back what has been taken away, resulting in having to purchase a new cylinder head.
Archive for June, 2010
Factory manufactured cylinder heads do not always perform as well as they could due to manufacturing restraints. A common process performed to modify the ports is called cylinder head porting. This process is essential in getting the most efficient amount and quality of air flow to the intake and outtake ports. By porting the cylinder heads, you allow the engine to perform at peak efficiency. The process is considered one of the most important factors in producing high power output from modern engines. Cylinder head porting can be used to enhance the performance of a standard racing engine or applied to a factory engine to increase power and performance.
The process is not one that is easy or without complications and is often best suited for a professional who provides cylinder head porting service. People trained and experienced in cylinder head porting have the skill and knowledge to achieve the desired results. With that in mind, there are still many people who prefer to work on their own vehicle. This may be due to budget restrictions or simply a desire to have the hands-on experience. For those who decline the use of a cylinder head porting service, there are a few common pitfalls in the porting process which should be avoided. Here are a few tips to ensure these pitfalls are not the downfall of your DIY project.
Be prepared- There is no point in starting the process unless and until you have all the necessary tools to do so. This includes the right cutting tools as well as the safety equipment needed to avoid injury. Flying metal and dust particles require at minimum- a good pair of safety glasses as well as a mask to filter out particles in the air. Have a shop vac handy to clean up your work area as you go, this can also be used to clear debris from the ports as you work.
Don’t rush the process- Depending on what material you are working with, the process can take a good 8-12 hours of time. That is of course if you are working with all the recommended tools and are able to fully concentrate on the job at hand during that time. Remember that when working with cast iron you will need more cutting time than aluminum.
Do your research before you start- New projects often require a bit of trial and error, however you do not want to begin this process blind. Research the products you are working with and the correct process used to reach your end goal. Having a well thought out plan of attack before strapping on the safety glasses will surely increase the likelihood of a positive outcome.
Know when to seek help- With the proper research and tools there is a good chance that you will be able to pull off the porting process on your own, however it is wise to know when to accept defeat. If you continue moving forward on a downhill project it will just end up costing you more money and time in the end. Be reasonable and do not allow your pride to get in the way of seeking professional help from a cylinder head porting service should you notice you are not getting the intended results.
More power! Horsepower! The goal of porting is to establish better airflow through the cylinder head. Some people mistakenly believe that cylinder head porting is about the port size – but it’s actually about air flow and how well the air travels through the ports. Many companies provide a cylinder head porting service to improve performance – but some die hard horsepower enthusiasts would prefer to do their own cylinder head porting.
For a novice, you won’t want to start with high performance racing heads, since they’re already top of the line and would offer little room to improve those through porting. It’s also important to understand that porting by inexperienced people offers unreliable results and a lot of trial and error as you learn the process. Most people who have tried cylinder head porting on their own fail to improve successful porting because they don’t have thorough knowledge of the fluid dynamics involved, or possess the tools and knowledge necessary to optimize a port.
At the very least, porting cylinder heads requires an air flow bench, and ideally the use of engine simulation software. An egg shaped carbide cutter will help you speed up the process of cutting. Using a Craftsman Professional 1/4hp rotary grinder and polishing kits from Standard Abrasives will help in the process of deburring a block, and polishing exhaust ports and chambers.
Don’t attempt this process for the first time on a good cylinder head. You should always practice on one that you don’t care about or need first.
Test the production of the cylinder head on an air flow bench before beginning cylinder head porting so that you can measure the results again when you’re done – to see whether you successfully made improvements – or reduced the air flow.
Remove Ridge from Intake and Exhaust Bowls
Before you start hacking away at the cylinder head, keep in mind that you want to remove as little material as possible. If you remove too much and create concaved or holes, the air flow is going to be adversely affected regardless of the size of cylinder head you are porting.
Start by placing the cylinder head on it’s exhaust ports and remove the ridge that forms within both the intake and exhaust, being careful to only remove material to half an inch of the bottom of the valve.
Feel around inside with your fingers for any high spots and use a marker to mark any area that still needs material removed.
Flip the cylinder head over so it is sitting on the intake ports, and remove the ridge from this angle. You should be left with all of the cylinder bowls having a nice, smooth circular contour.
Unshroud the Valves
Remove the good intake and exhaust valve and set aside. Place the old valves in the cylinder in place of the good ones, in case you accidentally nick them when doing the next step.
Get the head gasket to line up with the dowel pins and the bolt holes. Stay within the bore line of the cylinder, and use the carbide cutter to scribe the line. Be careful though, if you get carried away and take off too much it will create a problem with sealing.
Replace the bad valves with the good ones again.
Using a Standard Abrasives (or other type of your choice) porting kit, polish all except for the intake bowls. Don’t polish the intake.
Test on Air Flow Bench
Once you’ve completed your cylinder head porting service yourself, test the flow of the heads on the air flow bench to see what kind of improvement you’ve made in air flow. After you test the air flow, test out the horsepower to see how much it increased.
High performance vehicles with enhanced power, braking, and suspension systems rely on high performance racing heads. Cylinder heads house the combustion chamber, usually sit on top of the engine block, and play an important role in the amount of horsepower a high performance vehicle can generate.
High performance vehicles, like race cars, may be more powerful than your standard car, but the trade off is the cost of maintaining them. They require more expensive parts and higher levels of maintenance to keep them running at the top of their game. If you want to keep your car’s horsepower where it should be – you should take strides to improve your high performance cylinder heads.
Racing is dirty for your car! The wear and tear, the dirt and grime from the track and oily parts causes the need for intense clean up and servicing between every race to ensure competitiveness. If you don’t take the time to return your car to near-perfect, like-new condition, you’ll find yourself at the back of the pack at the next race. The dirt and grime that gets into your engine isn’t always visible from outside. The heat from the engine combined with the dirt can turn vital car parts into scrap metal! You can prevent this type of wear and tear through a good maintenance program designed to improve high performance racing heads and the rest of the parts inside your high performance vehicle engine.
Part of your maintenance schedule should always involve the detailed cleaning and refreshing of the high performance racing heads.
Remove high performance racing head from motor so you can work with it freely. Place it in a jet washer for ten minutes. A jet washer is used to remove rust, oils, and any other dirt or grime with a solution that would burn your skin if you touched it.
If the head comes out with dirt and grime remaining, and it is a cast-iron head, run it through the jet washer cycle again or put it in a shot-peening machine. Never put an aluminum head through a shot-peener.
Put the head through a glass beader machine to clean the combustion chambers. Once it goes through this machine, the chambers can be checked for cracks with a Magnaflux test.
Remove By Hand
If after all of this technology the high performance racing head still has some remaining gunk caked-on, use a screw driver or other tool to scrape it off by hand.
If you are working with cast iron high performance racing heads, the combustion chamber of the high performance racing heads receive a dusting of very-fine metal shavings. A magnet will cause the shavings to stick to the combustion chamber walls, which will then show if there are any cracks or not. Magnaflux tests will not work with aluminum heads because the metal shavings dust will not stick to aluminum.
A thorough testing of the high performance racing heads will also include a check of the valve stems using a micrometer. If there is too much variance in the thickness of the valve stem, it gets tossed and a new one is put in. A 3 to 5 angle valve job is then completed, and the high performance racing head is ready for installation.
There are many hobbies that people enjoy that do not cost an excessive amount of money. Car racing is not one of them. Unless you are a professional driver or have the backing of generous sponsors there is a good chance that your racing hobby is one that costs you a lot of money that can often be an issue when trying to keep your budget in balance. This is especially true when you are building your race car. Whether it is your first go round or you have experience building top performing vehicles, the cost will surely be something you want to keep in mind when you begin your venture. Here are a few tips to ensure your hobby doesn’t break the bank.
- Know what you will need before you begin- Depending on what type of racing you plan to participate in, there will be certain rules and restrictions which must be considered before you get down to the dirty work of building your car. A new engine is almost always in the cards, however how much modification is allowed will greatly limit your options. There is no point in investing in high performance racing heads or other modifications if the rules state your car must be stock. In doing your homework ahead of time you can eliminate spending money where it isn’t needed and focus on spending it where it is.
- Save money with used parts- There are many people who are known as “junkyard hunters” who have great success in finding parts they can use for a fraction of the cost of buying it new. There may also be cases with older models where new parts are simply not an option and buying used will be the only way to get your hands on the necessary equipment needed.
- Safety first- While there are always areas where you can pinch pennies, the safety of yourself and the other drivers and spectators should never be an area where you skimp. Make sure the equipment you are working with is in good working order to ensure you can get the most out of your hobby without harm coming to anyone in or around your vehicle.
- Areas of focus- When you are working with a limited budget the main areas of focus should include reducing the overall weight of the car, maximizing handling, improving the aerodynamics and high endurance. Modest changes in these areas can be accomplished on a smaller budget while allowing you the opportunity to participate in a sport you enjoy.
- Find a mentor- If you don’t already have a mentor who can offer advise and share expertise, make it a point to find a person like that who can help you throughout the process. Some of the best advice is not found in books, magazines, online forums or websites, but rather in the heads of those who have been in the sport for years. Consider this an invaluable resource that shouldn’t cost any money but can provide information that will help you in your endeavor.
Vortec cylinder heads feature a chamber shape and intake port that allow a large amount of air to mix with fuel for high air and fuel mixture velocity. The intent of GM engineers was the same as that of most builders of performance engines: to increase horsepower of the Vortec engines, as well as torque.
Because General Motors has two Vortec cylinder heads on each new truck they sell, they’re literally selling several hundred thousand heads. Selling Vortec cylinder heads at this volume gives GM the ability to spend money on research and development to improve the performance of the cylinder heads. It also makes it possible for replacement cylinder heads to be priced reasonably.
Features of the Vortec Cylinder Heads
Combustion Chambers – in a Vortec cylinder head, the combustion chamber measures a liquid volume of 64cc. Depending on what type of engine, this small size may be either a disadvantage or an advantage to the overall performance.
Size of the Valves – despite changes in other areas of the Vortec cylinder heads, valves are about the same dimensions as other small-blocks. Vortec cylinder heads have a valve stem measuring 11/32-inch in diameter, which was common before the 1970s. Most other small-block heads are now being designed with valve heads of 3/8-inch in diameter.
ValveSprings - Vortec cylinder heads have newly created “valvesprings”. These springs become damp on their own without a damper.
Intake Ports – like combustion chambers, intake ports have liquid volume measurements. The Vortec cylinder heads feature larger than average intake ports. In 1986 or earlier, traditional cylinder heads were measured to hold 160cc’s. The Vortec cylinder head holds more liquid, 170cc’s, because it was designed to have a taller intake port. By making the port taller, the overall radius of the intake port is larger, which succeeds in holding more liquid and improving the air and fuel mixture in order to maintain velocity as the air moves through. More air and fuel mixture velocity translates into higher horsepower and lower torque – meaning the goals of GM have been achieved!
Disadvantages of Vortec Cylinder Heads
One issue many car owners consider a disadvantage of the Vortec cylinder heads is that a different intake port manifold must be purchased. The standard intake manifold will not work with the head due to the taller height of intake ports on Vortec cylinder heads; and the different size and number of the mounting bolds of the intake manifolds.
Another disadvantage of Vortec heads is the valve lift limitations. If the lift exceeds .470 inches, the valveguide gets pinched between the guide and retainer. Originally, GM designed an o-ring and tin shield over the spring that would not prevent all oil from reaching the valveguide. It was thought that a little bit of oil finding it’s way to the valveguide would improve performance and act as a lubricant, therefore increasing the life of the valveguide. In 1970, a Federal Clean Air Act made this illegal, and GM had to redesign a seal that would eliminate any oil from seeping into and past the valveguide.
Vortec cylinder heads are cast iron. They’re the first of cast iron cylinder heads used for individual-port fuel injection. This eliminates the exhaust heat crossover passage which helps vaporize fuel that builds up on the intake manifold floor.
Cylinder heads play a vital role in the function of an internal combustion engine. Often referred to by car enthusiasts as simply “heads”, the cylinder head is located above the cylinders which are on top of the cylinder block. Cylinder heads house the spark plug that is needed to create the explosion necessary to move the pistons, creating mechanical energy for the engine. There are several different types of cylinder heads on the market each with their own unique properties that affect engine performance. A common question that is asked within the automobile industry is which type of cylinder head is the better performer, cast iron or aluminum. This is a question that is not easily answered as it depends on a number of factors.
The difference between the two types of cylinder heads goes beyond the material used to make them. Both cast iron and aluminum cylinder heads have their own benefits as well as drawbacks. The question of which type of head is better really depends on the intended purpose of the vehicle.
Cast iron cylinder heads have been around for a long time and some people will say they are better then aluminum heads. In some situations they would be right, but not all. Here we look at some of the differences between the two and why one might be better than the other in certain applications.
Cast Iron Cylinder Heads
Used for both racing and passenger vehicles, cast iron cylinder heads are generally considered more durable and believed to make more power due to the fact that the chamber holds in heat. As one would guess from the material used in manufacturing, cast iron cylinder heads are heavier than their aluminum counterparts which usually weigh at least 50% less than the cast iron cylinder heads. Cast iron cylinder heads are often preferred by day-to-day drivers who find them to be cheaper and less expensive to maintain as they tend to have fewer cracks and blown gaskets. On the down side, when cast iron cylinder heads do require attention it can be not only time consuming but expensive to repair. Despite being preferred by day-to-day drivers looking for an inexpensive and durable cylinder head, cast iron cylinder heads are also used in racing vehicles. In fact, certain race tracks are mandated as “iron only”.
Aluminum Cylinder Heads
Aluminum cylinder heads are popular among much of the racing set as they are lightweight, and produce more torque than cast iron cylinder heads. Despite the issue of dissipating heat, aluminum cylinder heads are usually easier (less expensive) to repair than cast iron cylinder heads. Close attention must be paid to certain areas such as fastener tightening procedures and issues with valve lash that result from the expansion of aluminum under normal operating temperatures.
In general both types of cylinder heads can be beneficial depending on what type of performance you are expecting from your vehicle. Understanding how each work and the benefits and drawbacks will help you better determine which type of cylinder head will best suit your needs.
Both cast iron cylinder heads and aluminum cylinder heads are difficult to clean whether by hand or with a cleaning system because of the passages and oil galleys in the designs. Cleaning the cylinder heads requires manual labor and can be difficult to accomplish in a high-volume production situation.
The process of cleaning cylinder heads may involve removing years worth of gunk and debris or it might involved cleaning a new head. Whatever scenario you are faced with, you need to ensure you have cleaned the cylinder head thoroughly before you can put it back to work or you’ll be looking at engine failure down the road.
There is a lot of concern about the typical cleaning products used for cleaning cylinder heads. Aluminum cylinder heads will not tolerate high temperatures so baking the dirt off is not an option. It may work for cast iron cylinder heads but may not be as efficient as other options.
Environmental concerns have prompted many from using VOC solvents because of the toxic effects it can have on humans and because solvents tend to evaporate quickly, making it harder to clean. There are also standards for disposing of the solvent waste to protect the environment.
Another option that is becoming more popular is an aqueous-cleaning system that uses water-based detergents. The Environment Protection Agency reports that aqueous cleaners contain less than 5% of VOCs. They have proven to be effective at cleaning aluminum and cast iron cylinder heads as well as the old solvents did. Plus the cleaning systems offer detergent solutions that will work on both aluminum and cast iron. The key to successfully using aqueous-based cleaning processes is the choice of detergent being used. Cleaning products are made for specific kinds of material such as cast iron and aluminum. There are also general purpose cleaners. Keep in mind that detergents can make all the difference and provide different results on one type of material you will not get on another type of material. If you have to clean aluminum and cast iron cylinder heads regularly, it may be worth the money to invest in separate cleaning systems as one cleaning product does not work effectively on both types of materials.
Some places are using ultrasonic parts washers that can remove dirt and oil effectively with high-frequency vibrations that essentially sends high pressured shock waves along the cylinder head that scrubs away the dirt by pulling it away from the cylinder head. The agitation also works well to loosen the oil and debris from the design cavities.
Thermal cleaning ovens have been used to clean cast iron cylinder heads very effectively. Some prefer the heat tactic because it dissolves the oil and dirt without much manual labor. In addition to the heating process, there must also be a step that involves the blasting of air. When the debris is loosened, the air is used to blast it off the part. The thermal cleaning process produces a very clean finish, making the part look new again. Other types of cleaning systems can not generate this same result for the finish results.
Your cleaning method for aluminum or cast iron cylinder heads will depend on what results you are looking to achieve as well as what your customers are looking for in a finished product. All are viable methods for cleaning cylinder heads and the choice is ultimately based on what works for your needs.
With just average welding skills, cracked cast iron cylinder heads may have more life left in them than you thought.
If you can weld steel, you should be able to repair a cracked cast iron cylinder head following these steps:
Clean the Cylinder Head Carefully
Because cast iron tends to soil easily from oil absorption, you’ll need to take proper care that it’s clean and dry before starting the repair process. Steam cleaning the metal, then using a degreaser is ideal for removing grease and oil. If you can, have an engine machine shop “cook” the head in a special degreasing vat designed for this purpose. Whichever method you use to clean it, you need to ensure it is good and dry to avoid rusting. Due to the tendency for cast iron to rust quickly, you should dry and begin the welding repair immediately.
Stop the Crack from Getting Bigger
Before you can begin repairing, you need to make sure the crack does not get any larger. If you can see the crack just by looking at the cylinder head, take a drill and create a small hole at the start of the crack. Then, from this starting hole, use a small die grinder to grind a small channel next to the crack to uncover fresh metal to help you weld and repair the part.
If you don’t see visible cracks, you may find the most cast iron cylinder heads get cracks near the water jacket areas or valve seats. If necessary, use a dye test to expose the crack so you know where to make your channel with the grinder. Purchase a can of dye penetrant from a car parts store or welding supply store, and spray it where you think the crack is. Wipe of the cast iron cylinder head and all of the dye will wipe off except for what has gone into the cracked iron itself. This will show you where you need to repair the part.
Heat the Cast Iron Cylinder Head
Heat the metal to between 170 to 200 degrees Fahrenheit. This will drive away moisture to prevent rusting, and relieve stress from the metal.
Begin Welding to Repair the Crack
Selecting the appropriate size and type of welding electrode is important to successfully repairing cracked cast iron cylinder heads. Most people find a very small diameter rod works best, and you should look for one that is meant for use on cast iron that has been soaked in oil. Most cracks in cast iron cylinder heads can be filled in one go. Once you’ve passed over the crack once, chip off the slag and then peen. Use a chipping hammer to tap the surface and relieve stress from the iron. It’s a process that ensures the end result is smooth. Relieve stress by allowing the part to cool slowly. You can cover it with blankets designed for this purpose which help pull the heat away slowly to avoid stress.
If you have never welded cast iron before, you may want to practice first. Get a scrap piece of cast iron, or ideally, a cast iron cylinder head that is beyond repair, to make sure you don’t damage the good one you’re attempting to repair.
The trademarked name Vortec first appeared on a 1988 GM model truck engine, 4.3 L V6. The name represents the technology which creates a “vortex” within the combustion chamber. This vortex is responsible for the mixture of air and fuel within the chamber allowing for better engine performance. The same concept has been applied to Vortec cylinder heads which have been in use since 1996. There is often some confusion as to whether or not certain cylinder heads are indeed “Vortec”, however there is little argument that this design will definitely improve engine performance and efficiency.
To determine whether or not you are purchasing and installing true Vortec cylinder heads you must first be able to recognize the difference between this type of cylinder head and the hundreds of other types available. To avoid confusion understand first that looking at a Vortec cylinder head from the exhaust side will look very similar if not exactly like that of all the other cylinder heads in use. The same can be said about the ends. The big difference and first indication that you are looking at a Vortec cylinder head is in the intake bolt pattern. The 8 bolt attachment as well as noting the casting mark will confirm if you are dealing with a Vortec cylinder head. The casting mark located at the end of the cylinder head will have a sawtooth or 3 triangle pattern.
The reason it is important to spot a Vortec cylinder head is to avoid confusing it with another design that will not deliver the same efficiency and power. Vortec cylinder heads are specifically designed using the same “vortex” technology to maximize combustion efficiency by evenly mixing the air/fuel charge. Since their introduction 15 years ago, there have been a number of different types of Vortec cylinder heads manufactured. For this reason it is not unreasonable to expect to find them in salvage yards and even at swap meets. You can also purchase them directly from GM either fully assembled or the bare casting.
Since the introduction of the Vortec cylinder head, many drivers have experienced the boost in performance and efficiency resulting from this unique design. This type of cylinder head can be found in all types of vehicles from racing vehicles to heavy duty pick up trucks. Any person who wants to increase power will find that Vortec cylinder heads will do the trick. The Vortec cylinder head like most other parts has continued to be tweaked and improved upon since it’s introduction. Today car enthusiasts can choose from a variety of models, however they should understand that other adjustments may have to be made based on the current set up under the hood. This may include changes in porting and other engine components to ensure everything is aligning just right to create the desired result of increase power, performance and efficiency. When Vortec cylinder heads are introduced to an engine set up it is not uncommon to see horsepower figured from 400 and up.