Once you get the hang of it, then start working in the bowl area. Carbides can remove a lot of material very fast so if you haven't used them before you should practice on the exterior or spare material. Start in the bowl area using carbide burrs to remove material and smooth the port, around the valve guide and bowl area transitions. ![]() The cutting fluid also seems to give you a little more leeway. Sometimes the tool will skip if you are not at the right angle or moving in the wrong direction. You will have to reposition yourself and the head several times to be in the right orientation and the needed direction for the work flow of the tool.Ĭutting fluid like Tap Magic can prolong the life of cutting tools and also make the cuts easier. Use your other hand to help support the tool hand and hold it steady. Position your hands to minimize any runaway. Be careful, the die grinder and carbide burr can skip or runaway on you. I use two different die grinders, one is straight the other is a 90 degree unit. Access and the area being worked on, determines which one to use based on control, reach and comfort. Look down the intake using a bright light and mark any protrusions into the port flow area. You may have to take the intake off and on a few times to double check.ĭouble check the size of each of the ports by measuring with dial calipers, making sure the markings will make the ports evenly sized. Next place the actual intake you are using and mark the location on the head to make it repeatable. The gasket helps but it doesn't define the port size. This gives you the largest size possible not the size you want. You can then mark up the intake and exhaust port maximum sizes. When the dye is dry, place the intake and exhaust gasket on the head and mark the position. Paint the machinist dye on the intake and exhaust face and then insert the head studs. I recommend using the dye and scribes as it lasts longer and is easier to see when the dust starts flowing. I found the sharpies are good if you need to just quickly mark a spot but it will rub off easily. I use a combination of sharpies and machinist dye. Mark up the intake and exhaust ports by scribing the areas to remove. If I hit them with a sanding scroll or carbide burr the hope was I would have a little protection before I start cutting into the seat. You will slip, you will make a mistake, so you want to minimize the size and magnitude of the mistake when you do. I used multiple layers of painters tape on and around the valve seats. When doing the bowls you want to be extra careful. Namely you are worried about the valve seats. Lets get started.īefore you start removing material, protect any areas you don't want to accidentally bugger up. This project took me a very long time with several hours spent at each step across all the ports. Match the intake and exhaust ports to the intake and exhaustĬlean up and smooth the transitions in the bowl areaĬlean up and smooth the transitions in port areaĬlean up and smooth the transitions around the valve guideĮven out and finish the intake ports to a 120 grit finishĮven out the exhaust ports to a 600 grit finish Here is my list of work prior to the machine shop: Then I made a second list for items to be done at the machine shop. I took notes as I went and then condensed them down into actionable items I could undertake. Theory and Practice of Cylinder Head Modification - David Vizard How To Modify Your Nissan & Datsun OHC Engine How To Rebuild Your Nissan & Datsun OHC Engine I spent a fair amount of time reading the following books: ![]() ![]() You are likely to ruin the head by hitting a water passage or worse. Don't jump right in and start grinding away with carbide burrs. Planningīefore you get started you want to come up with a plan. You will be amazed how filthy and dirty the bench, surrounding area and even garage gets. Grinding and sanding will produce a lot of fine metallic particles and dust, make sure you have proper safety equipment safety goggles, gloves and a particle filter respirator mask. If you don't have spare material around you can always try cosmetic clean up on the exterior casting. I also recommend using your tools on a similar material so you can get a feel for the amount that is removed with each pass based on revolution speed, pressure and contact duration. ![]() Before you attempt porting you should read up about what you are trying to achieve and watch a few videos.
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