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Eastwood Auto Restoration Blog - Free How-to Automotive Tech Advice for Everything DIY Automotive

  • How to Port and Polish Cylinder Heads

    Porting cylinder heads for better performance is as much an art as it is a science. Strange as it may seem, just making the intake and exhaust passages bigger will not always improve performance, and may actually hurt it. The expert port polishers are still guys with a lifetime of experience and the ability to visualize the invisible gas flow at high speed in 3D. They are like wizards. But there are certain easily done basic techniques that even a beginner can learn and that work on all engines. Doing just the basic gasket matching, port smoothing and bowl blending it is not unusual to see 10% power increases across the board.

    Safety First

    First things first, you need the proper safety gear. Porting and polishing involves grinding away metal and as such there will be grit, grindings and dust flying once you spin up the tools. Safety googles and a dust mask are a minimum; you may want a full face shield. Gloves are also a good idea, not only to keep your hands clean, but to keep from grinding off any fingerprints. Be extra careful around loose fitting clothing, jewelry and long hair; tuck it in, remove it, or tie it back before you start.

    Porting KitThe Tools

    There are not a lot of tools needed to do your first porting and polishing job. You will need an electric or air powered high speed die grinder, some abrasive rolls and the mandrels they mount to, all of which are included in the Eastwood Engine Porting Kit with Die Grinder. Also available in a mini die grinder kit, or with just the rolls and mandrels. You may also want some carbide burrs, which are especially helpful if you are working with cast iron. If you are working with aluminum or other soft metals you may want a tube of Eastwood Grinder’s Grease too, to help keep the tools from loading up with metal.

    The Three Basics

    Gasket Matching – Gasket matching is the process of matching the size of the port to the size of the intake gasket. Often times there is an overlap where the intake manifold runner is slightly bigger than the opening it mates to in the cylinder head. By tracing the opening of the gasket on the mating surface of both head and manifold you can be certain the flowing gas has a smooth transition between the two. It is not important to open them up bigger, the important thing is that there is no step that disrupts the flow.

    Port Smoothing – Here in the 21st century cylinder heads come direct from the foundry with ports much smooth then was imaginable back in the 1950s when most classic power plants were being cast. On top of improved casting techniques, the design of the ports is much better too. But most old school cylinder heads have rough cast ports that can be much improved with a little work. Firstly, you want to grind out any shark, jagged, left over casting flash in the ports. Secondly, you want to smooth any sharp transitions or obstructions in the port. And lastly, you want to generally smooth the port walls. Be careful on the intake as a slightly rougher wall helps fuel atomization. Above all remove as little metal as possible.

    Bowl Blending – Blending the surfaces of the combustion chamber, or bowl, has 2 benefits. One, eliminating sharp edges helps stop pre-ignition from localized hot spots. Two, unshrouding the valve lets the mixture flow better into and out of the combustion chamber. It’s a good idea when working in this area to insert an old set of valves so you can avoid grinding too close to the seats. Remember, making the chambers bigger will decrease the static compression ratio, so again, take out just as much metal as you need too. Never use a carbide burr in the combustion chamber, they are much too aggressive and will remove too much metal.

    How To

      1. Take a good new intake gasket and attach it to the head loosely with a couple of bolts.
      2. Scribe a line around the ports, using the gasket as a template. A carbide scribe of finishing nail works great, you can also use a Sharpie but you will quickly rub off the ink.
        porting 1
      3. Depending on how much material you need to remove, start grinding away with the carbide burr or an abrasive roll. Don’t grind in any one area too much. Instead work around and around the port removing a little bit at a time until you have opened it up to your scribed line. Later you can use the same technique on the intake manifold ports too.
        porting 2
      4. Once the ports are opened up properly, continue to grind and smooth your way toward the valve seat. For the sake of durability and good sealing try to stop your grinding 1/2 inch before the actual valve seat.
      5. Feel and look inside the port to find any flash and rough jagged edges left from the casting process. You may want to attack these with a carbide burr first to speed things along. Grind these smooth.
      6. Then work the cylindrical and tapered drums around and in and out of the port until it is a uniform smoothness throughout.
        porting 3
      7. Flip the heads over and work the area under the valve seat. There is usually a sharp ridge in the port in this area that should be smoothed into a more gradual transition. Again, be extra careful not to cut into the valve seat itself, or weaken that area.
        porting 4
      8. A particularly important area of the intake port to smooth is the short side radius. This is the sharp turn the port has to take as it changes direction just before the valve seat. In this picture it is below and just ahead of the tapered abrasive roller.
        porting 8
      9. It’s a good idea to work all the intake ports, then the exhausts, then the chambers. That way you are more likely to get more uniform results. It will also take less time this way, as you will be able to work faster as you practice on each port.
      10. There is no need to gasket match the exhaust ports to the header or manifold. In fact popular wisdom holds that having a smaller port and a step will help scavenging and limit reversion. Reversion is the exhaust being sucked back into the cylinder during the brief period when the valve is opened and the piston is on its way back down for the intake stroke.
      11. Smooth the same sorts of casting issues and sharp edges you addressed in the intake as you work the exhaust ports. Unlike the intake, which prefers a rougher finish to promote fuel atomization, the exhaust can be polished to a mirror finish if you want. The smoother the finish inside the exhaust the less likely you are to get carbon build up over time. Eastwood offers abrasive drums in 240 and 320 grit specifically for this.
        porting 5
      12. Next on to the combustion chambers. The very first thing to do on the chambers is knock off the sharp edge all the way around left from milling the heads. Just take an abrasive roll and make one lap all the way around the edge of the combustion chamber.
        porting 6
      13. It’s a good idea while blending the combustion chambers to put an old set of valves in to protect the seats from your abrasive tools.
      14. Smooth and grind and rough casting areas within the combustion chambers. Remember, every added CC of metal you grind away will lessen the compression ratio, so grind away as little as possible (unless a lower CR is one of your goals).
        porting 7
      15. Depending on what motor you are working with, there may be problem areas in its design that are known to shroud the valves and affect flow. Consult the internet for more specific information about your project.
      16. After working the combustion chambers it is a good idea to CC them and make sure they are all equal. This is done by putting the valves in and covering each chamber with a flat piece of Plexiglas with a hole in it, sealed to the surface with a little grease. Use a graduated cylinder to measure how much fluid it takes to fill it entirely.
      17. How-to-CCRepeat porting process on the intake manifold runners and exhaust manifolds (if running OEM style cast iron). Headers do not need any extra attention; tubular headers are typically already smooth inside.
      18. Clean everything thoroughly inside and out to remove all the metal shavings and abrasive grit before starting to reassemble the motor.

    That is all there is to porting cylinder heads. At least, that is all there is to the technique of porting heads. All you need to learn now is the art of exactly what and where to grind away in order to reshape the ports for best flow. That is going to be different for every motor, and even every different cylinder head casting for each motor. For more of the art behind optimal porting Eastwood offers a 160 page book by David Vizard called “How to Port & Flow Test Cylinder Heads”. This book delves deep into flow characteristics and how to improve them. It also shows you how to build a flow bench to test your work in the shop, before the motor goes together.

     

    Check out the Eastwood Blog and How-To Center for more Tips and Tricks to help you with all your automotive projects.  If you have a recommendation for future articles or have a project you want explained don't hesitate to leave a comment.

  • How To Outfit Yourself to Paint Safely

    One of the things that makes modern, 2K paints so long lasting and durable is one of the same things that makes them harmful to your health. The activated 2K reaction does not require air to “dry” so it will harden anywhere it goes, including into your lungs and other orifices.

    Not only will the paint harden anywhere it gets, but it also contains isocyanates, which are irritants that will attack your eyes and respiratory system.

     

    Don't forget these Painting Essentials!

    Respirator

    • Proper Respirator - You should not be spraying any paint while wearing a woven dust mask. To keep your lungs in good condition you need a real respirator. When you begin to smell or taste what you are spraying it is time for a new one, or new filter cartridges.

     

    full face mask

    • Forced Air System - If you do a lot of painting, a turbine air system is a better idea. A hose and mask connects to a turbine which picks up clean air from outside your spray booth and pumps it to you.

     

    non air fed mask

    • Eye Protection - Since isocyanates irritate your eyes, you need an eye mask or goggles too. You can buy a full face mask respirator or one that works with the forced air system.

     

    gloves

    • Gloves - If you don’t already have nitrile gloves in your shop you don’t know what you are missing. Even if you don’t wear them all the time, when painting or using chemical solvents they are a must. They are cheap too, and also they keep skin oil from your fingers off what you are painting.

     

    pcoveralls_1

    • Coveralls - Besides the fact that spraying paint will ruin your street clothes, lint and threads could ruin your paint. Better to buy several sets of painters coveralls, and head socks. Isocyanates aren’t friendly to your skin either, so best to wear something they can’t seep through, like our lint-free, liquid proof coveralls and head socks.
  • How To Weld a Butt Joint

    One of the simplest welding joints is the butt joint. It is not the strongest, but it is one of the most useful especially for automotive body work. This type joint is used whenever you butt 2 pieces together and then weld between where the two meet. Butt welding thin sheet metal can be complicated because thinner metal has a tendency to burn through on the edges. This doesn't mean it's impossible, just that there are techniques that can be used to minimize these issues.  

    P1030747

    Because the edge of a piece of metal absorbs heat faster than a solid surface, you need to modify your technique with the electrode. Whether you are using wire feed, stick or TIG welding, you need to move the electrode quickly and dance around the weld area, to avoid burn through. With the stick welding technique, this can be done using a stitch welder, which moves the electrode in and out like a sewing machine needle when you pull the trigger.

    When done properly, a butt joint should show bead on both sides of the metal. One way to help insure this is to clamp the 2 pieces with a uniform gap between them. The Eastwood Butt Weld Clamp and Backer Set holds sheet metal slightly apart for better weld penetration and also helps hold the work tight to prevent warpage from the heat. These clamps also help to prevent crawl, which occurs when the metal tries to move away from the heat of the work area.

    Even with clamps, the first step in a butt joint is to tack weld along the entire length of the joint. Start with a weld every few inches, at a uniform distance, then go back and fill in with more tack welds between the first set. Before moving on to the final bead you should have welds about an inch apart along the entire joint. Even with this technique, there will be some distortion that needs to be hammered out afterwards, but this will help minimize it.

     

    P1030751

    Some welders prefer to use a weaving/zig zag or circular technique with thinner metals. This leaves you with a wider bead than you need, but it helps to spread out the heat of the weld to minimize burn through and warping. Before doing butt welds on something important, practice different angles with the electrode, rate of travel of your welding and length of your arc until you are comfortable with the thickness you need to weld, and establish your technique to avoid burning through it.

    How to weld a butt joint

    The picture above shows 4 different welds in cross section that you are likely to see when making TIG welded butt joints. Figure B shows correct technique, while examples A, C and D have various issues.

    P1030713

    A: A common mistake beginners make is to pile too much bead on the top side of the joint, in an attempt to keep from burning through. This can be because the weld was not hot enough or more likely because the electrode was not close enough to the surface for proper penetration. For a butt joint to be acceptable, the bead should envelope both edges on both sides of the work, so no trace of the original edge can be seen.

     

    butt weld b

    B: This is an example of the correct penetration of a butt joint. There is bead showing on both sides of the work, with the lower bead being slightly smaller than the upper weld.

     

    butt weld c

    C: When you have too much penetration, the weld will begin to show undercutting and take this shape. You can see how the bead has begun to sag through the joint and not fill the top side fully. Undercutting is where the thickness of the weld is actually less than the work being welded, which means a weak joint.

     

    tig17

    D: This shows even more penetration and undercutting; the top bead has taken an almost concave shape. This is an even worse example than the one directly above.

     

    In addition to the common problems, there are also a few different ways you can prep the metal before it is welded.  The following only really applies when welding metal 1/8" or thicker because any thinner and you will almost always burn through.

    P1030753

    The first and most common is known as a square butt weld.  This is done when two flat pieces are up against each other. this is used for thinner metals and TIG welding.  If welding metal thicker than 3/16" this method should not be used because the weld will not penetrate far enough into the metal and will not be as strong.

     

    P1030750

    The next type of but joint is known as a bevel or double V joint. This type of weld is a must when welding metal 1/4" - 3/4".  When the edges of each piece are ground down it creates a valley or grove for the weld to sit in, this gives more surface area for the weld to bond the two panels.

     

    P1030748

    The third type of butt joint is known as a double bevel or double 'V" and is the strongest type of butt joint.  This type of joint is used in areas where weld strength is critical.  This type of weld is usually used when welding metal thicker than 3/4" but can also be used on thinner metals if more strength is needed.

     

    It is true that the strength of welds when doing butt joints to body panels is not as critical as when doing structural repairs. However, properly welded butt joints will make the repair look better with less grinding and body filler. A well done joint will also last much longer, while a poorly done repair may crack and ruin the paint and body work after just a few miles of driving. Because of this, it’s important to practice and get the underlying repairs correctly done before moving on to the next phase. Learn the proper butt joint technique, and you will use it on countless welding jobs.

  • Repair Manuals Will Save Your Project

    If you plan on doing any type of serious work on your car or even just basic maintenance its a good idea to to buy a vehicle specific repair manual.  Depending on the car you drive it may be harder to find the exact manual, but for the most part a simple internet search will help you find the correct one for your car.  If you think buying one of these is not necessary you should probably reconsider.  The companies that produce these manuals have already done all the hard work for you.  These manuals usually have step by step instructions on how to take apart and reassemble every part of your vehicle, some even will show a full engine break down.

    Nova Manual

    Going in to a project blind can be fun because we all want to figure everything out for ourselves and not have any help along the way.  What happens if you hit a wall in the middle or forget how something goes back together? In this situation you only have a few options, even searching the internet may not help because you may already be over your head.

    engine

    Having a repair manual will allow you to go into a project without any unknowns, some will even give tips on the exact way to remove the part so you don't break it.  I know first hand that my car would not be running today without the help of a repair manual.  If your vehicle requires special tools, a manual will not only tell you what tool you will need, but also give a part number which will make locating one easier.

    suspension

    Check out the Eastwood Blog and Tech Archive for more How-To's, Tips and Tricks to help you with all your automotive projects.  If you have a recommendation for future articles or have a project you want explained don't hesitate to leave a comment.

    - James R/EW

  • How Air Compressors Work

    The concept behind the air compressor is a simple one and easily understandable to anyone who is into old cars and such. The reason the pump on the top of your compressor looks like a simplified motorcycle engine is because it basically is. The vast majority of compressors, from the tiny 12v tire inflator you stash in your trunk to the big 80 gallon shop unit, basically compress air with an air cooled piston engine. In fact, there are kits to turn air cooled VW bug motors into gas powered air compressors that could be mounted in the bed of a truck; two cylinders power it and two compress the air.

    img-y

    When the electric motor kicks in, the piston is drawn down the stroke of the cylinder. A simple spring-loaded one way valve opens allowing clean atmospheric air in, usually sucking thru some kind of air filter to keep out dirt and dust just like your car. The piston then moves up, compressing the air, and a 2nd valve opens to let the now pressurize air into the tank, or out into your tire in the case of a tire inflator or the one outside at the gas station. When a gauge signals that the tank has the correct pressure, the motor stops.

    Because air tools, spray guns and the like only allow the air out thru a restriction, the tank stays pressurized for a while. If an air hose were to break, the air would all come out pretty quick and return to atmospheric pressure in seconds. The CFM rating on a compressor indicates how many cubic feet of air per minute can leak out via the tool you are using before the pump would be unable to keep up with the demand at a given pressure.

    Multi-Stage and Screw Compressors

    There are variations on how air compressors work. There are multi stage reciprocating compressors, and nearly silent rotary screw compressors.

    Pistoncompressors-2

    Two stage compressors typically have a v-twin looking head on top of the tank. The first cylinder works just like a single stage, but instead of feeding the tank, it feeds the intake on a second smaller cylinder, the second cylinder, then compresses it even more. There are also three piston versions that work the same way, as well as single stage multi-cylinder units for more air flow at lower pressures.

    oilfree rotary screw casing_tcm1340-3536433

    Rotary screw compressors work more like a Roots-type supercharger. Two rotors intermesh, forcing air into a smaller space along the length of the rotors, and finally out into the tank. Because of how they work, they produce more of a constant “whir” then the “chuga-chuga” of a reciprocating pump. This makes them popular for applications where noise is an issue. This type of compressor is also generally used in larger industrial application because of its increased efficiency and ability to deliver larger volumes of air at high pressure.

    Care and Maintenance

    wscdr02a

    No matter how you compress the air, you have to deal with the physics of thermal dynamics and moisture. Squishing the air makes it hot, it’s an unavoidable by-product of compression, which is why some units have cooling fins on the supply line to the tank, or even a separate intercooler. All air has moisture in it too and compressing it results in condensation, which is why you need to drain the tank occasionally, and use an air dryer in applications like spraying paint. Just like an engine, compressors need to be lubricated, and if you are spraying paint, you need to strip the oil out of the airstream as well as the water. Luckily, most air dryers function this way already.

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