Porting cylinder heads
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The purpose of this article is to acquaint engine builders on the tangible benefits of cylinder head porting and making more power through the porting process. Cylinder head porting or 'porting' as it is known in the hot rod circles, is classed by some as '''black magic''' in the engine building process. Proper porting procedures will result in getting the largest volume of air/fuel mix to the combustion chamber in the shortest amount of time. Porting works hand in hand with valve grinding and seat cutting. | The purpose of this article is to acquaint engine builders on the tangible benefits of cylinder head porting and making more power through the porting process. Cylinder head porting or 'porting' as it is known in the hot rod circles, is classed by some as '''black magic''' in the engine building process. Proper porting procedures will result in getting the largest volume of air/fuel mix to the combustion chamber in the shortest amount of time. Porting works hand in hand with valve grinding and seat cutting. | ||
| − | ==Areas to | + | ==Areas to work on== |
| − | During the manufacturing and machining processes of a cylinder head, there are areas that are left unfinished. This is due to cost/time restraints imposed on the manufacturers | + | During the manufacturing and machining processes of a cylinder head, there are areas that are left unfinished. This is due to cost/time restraints imposed on the manufacturers. |
When a port is machined for a seat, often a lip is left below the seat. This lip is sometimes semi-removed using a type of tapered reamer that helps smooth the transition from the seat into the pocket portion of the port. But because this is done quickly and by machine and not carefully and by hand, there is still almost always places where improvements can be made. | When a port is machined for a seat, often a lip is left below the seat. This lip is sometimes semi-removed using a type of tapered reamer that helps smooth the transition from the seat into the pocket portion of the port. But because this is done quickly and by machine and not carefully and by hand, there is still almost always places where improvements can be made. | ||
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[[File:049 bowls.jpg]] <br style="clear:both"/> | [[File:049 bowls.jpg]] <br style="clear:both"/> | ||
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===Layout dyes=== | ===Layout dyes=== | ||
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Another type comes as a liquid in an alchol base that can be sprayed or wiped on. When the alcohol evaporates, the dye is left behind for scribing. | Another type comes as a liquid in an alchol base that can be sprayed or wiped on. When the alcohol evaporates, the dye is left behind for scribing. | ||
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==Step by step porting methods== | ==Step by step porting methods== | ||
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*Gently move it around the perimeter of the opening once or twice. Check the surface for texture and note how close you are to your scribed line. | *Gently move it around the perimeter of the opening once or twice. Check the surface for texture and note how close you are to your scribed line. | ||
*Chuck up a 180 grit roll and move around the perimeter again one more time. | *Chuck up a 180 grit roll and move around the perimeter again one more time. | ||
| − | *Finish off by tilting the roll 30 - 45 degrees | + | *Finish off by tilting the roll 30-45 degrees and go around the outer edge and remove the sharpness off that edge. |
*Blow off the sanding dust and clean the gasket surface. | *Blow off the sanding dust and clean the gasket surface. | ||
*Place the gasket on, insert your bolts and check to see how the gasket fits the opening now. | *Place the gasket on, insert your bolts and check to see how the gasket fits the opening now. | ||
*Match the housing to the gasket to the surface the same way as you did the intake and you should have a perfect match. | *Match the housing to the gasket to the surface the same way as you did the intake and you should have a perfect match. | ||
*Apply this process to the other gaskets on your heads for optimum flow. | *Apply this process to the other gaskets on your heads for optimum flow. | ||
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| + | ==Valve job== | ||
| + | A three or more angle valve seat is best for flow. Most shops today use a multi-angle cutter that does at least three angles all at once. This is an acceptable method for most performance engines, but a skilled machinist can use individual stones to give a superb result, placing the angles exactly where they need to be. This method also allows the seat widths to be set by the machinist and not the tool. | ||
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| + | [[File:Multiangle valve seat.jpg|500px]] | ||
==Other related areas== | ==Other related areas== | ||
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