Tweet
I'm in the process of porting out my head and i though i would share what i came across from my researching. This will be my first P&P and I'm feeling pretty comfortable. It's not as hard has people think it is. All you need is time and patience. Well i decided to make this thread just incase some one like me wants to do there own head work and learn from it.
Good useful information by: Turbo94HatchOR
Valves and Seats
The use of stainless steel valves will always improve flow over standard stock valves, as they have a much tighter radius on the backside, allowing for less obstruction at the opening when the valves are open at low lifts. A good 3-4-5-angle valve job will enhance the flow improvement even more. You can pay a professional to do this work. I have access to some really nice grinding stones at work and have good success grinding the valve angles by hand, with the exception of the sealing 45 degree angle. I leave that one alone.
Port and Chamber Area Around the Seat
The valve seats are steel inserts pressed into the aluminum casting. There is usually a mismatch of metal in the port and in the combustion chamber. Take time to blend the port and chamber until the step (mismatch) is gone, using your finger to feel for imperfections. When working around the valve seat, take extreme care not to accidentally nick the 45 degree angle in the set, or you will be taking the head to the machine shop for dressing the seat. If the heads are used, the do the port work first.
Combustion Chambers
Too much deck height is a bad thing, resulting in loss of turbulence at TDC when the mixture is ignited and reduce combustion efficiency. Deep combustion chambers are another problem, as they tend to shroud the valves giving very little room for flow around the valve into the chamber. I like to lay back both the plug side and non-plug side of the chamber by widening the angles. I also unshroud the valves by opening the sides of the chamber up to the cylinder bore diameter. I then blend all this together, smoothing all imperfections and casting marks. This means that the chamber is opened up all the way around, making for a much clearer entry for gasses into the cylinder (and exit for the exhaust). I then flycut the heads to get the desired chamber CC's (with .050" - .070" deck height). I then use a flapwheel to remove the sharp edge all the way around. Take care not to round the sides where the cylinder will seal against the head. It is a good idea to scribe a line around the head where the cyl will meet the head, and to drop some junk valves into the heads to protect the valve seats while working in the chambers.
The goal is to provide the best port-match for the specific valve. "Hogging it out" is not the goal. The stock size port does not need to be enlarged very much to get good results, and too big of a port will cause a loss of port velocity and create unwanted turbulence. The goal is to reduce the restriction of the port.
Set the head in front of you with the intake flange facing you (right side up). The ports are round, and we are going to make them oval in the direction of the sparkplug holes, similar to a "V" shape. If you have a intake gasket or pattern to borrow, now is the time to draw/scribe it out onto the intake flange. Hold the grinder perpendicular to the flange and open up the ports to the new port shape. Don't worry about blending into the port yet. Take your time and make all the port openings look the same.
Set the acorn file out as far as you can in the grinder to give maximum reach into the port. On most heads the port has a casting part line right above the intake guide boss. This part line makes for a major corner right above the guide boss blocking any flow trying to go over top of the guide. You will want to blend this corner away by plunging the grinder down through the port going over top of the guide boss. Once through, work from the chamber side of the port to blend the contour. There is a fair amount of metal to remove here so take your time and study the port closely. The goal is to make the port above the guide look like it does below the guide, in effect straightening the port. This will open up a new flow path for intake charge. I also like to thin the intake guide boss, as it does very little anyway. Shape the metal into a nice teardrop shape around the guide, working from both ends of the port.
Once the major porting has been performed, blend the whole port together, removing all the bumps and corners, radiusing the port into the new openings. Use your finger to feel for irregularities. The contour should be one nice smooth blend all the way to the valve seat. Work slowly!
Exhaust Ports
I pretty much go by the book here. Without removing too much guide boss material, I like to contour the boss much in the same way that we did the intake bosses. Because the boss takes up so much of the port in that area, it helps flow to widen (or squeeze) the port around the boss. Working from the seat side of the port, start widening the port on either side of the boss just below the seat. You can blend these wide pockets into the port from the exit flange side. There is a sharp edge on most heads on the inside radius of the port, and it is almost impossible to see (you have to use your finger to find it). Tighten-up the inside radius, leading away from the seat, blending this edge away. Do not take too much material away here or there will not be enough left to support the seat properly. Lastly, open up the port at the header flange. Use an appropriate size exhaust gasket for this pattern.
What is Head Porting? ( All you need to know before you begin)
Parts of The Port
Basic Cylinder Head Porting
Porting How-to
Head Porting At Home
CC'ing Your Heads
Valve Shrouding
If you don't feel like doing your own Head Porting. There are Companies out there that will. ( If I;m forgeting someone just add as you go)
Comapnies:
http://jgenginedynamics.com/JGE%20main%20page.html
Videos
Cylinder Head Rebuild
Wet Flow Test
Port Flow Turbulence Test
Pictures
From:Combustion Contraption
^love this guys work
Good useful information by: Turbo94HatchOR
Valves and Seats
The use of stainless steel valves will always improve flow over standard stock valves, as they have a much tighter radius on the backside, allowing for less obstruction at the opening when the valves are open at low lifts. A good 3-4-5-angle valve job will enhance the flow improvement even more. You can pay a professional to do this work. I have access to some really nice grinding stones at work and have good success grinding the valve angles by hand, with the exception of the sealing 45 degree angle. I leave that one alone.
Port and Chamber Area Around the Seat
The valve seats are steel inserts pressed into the aluminum casting. There is usually a mismatch of metal in the port and in the combustion chamber. Take time to blend the port and chamber until the step (mismatch) is gone, using your finger to feel for imperfections. When working around the valve seat, take extreme care not to accidentally nick the 45 degree angle in the set, or you will be taking the head to the machine shop for dressing the seat. If the heads are used, the do the port work first.
Combustion Chambers
Too much deck height is a bad thing, resulting in loss of turbulence at TDC when the mixture is ignited and reduce combustion efficiency. Deep combustion chambers are another problem, as they tend to shroud the valves giving very little room for flow around the valve into the chamber. I like to lay back both the plug side and non-plug side of the chamber by widening the angles. I also unshroud the valves by opening the sides of the chamber up to the cylinder bore diameter. I then blend all this together, smoothing all imperfections and casting marks. This means that the chamber is opened up all the way around, making for a much clearer entry for gasses into the cylinder (and exit for the exhaust). I then flycut the heads to get the desired chamber CC's (with .050" - .070" deck height). I then use a flapwheel to remove the sharp edge all the way around. Take care not to round the sides where the cylinder will seal against the head. It is a good idea to scribe a line around the head where the cyl will meet the head, and to drop some junk valves into the heads to protect the valve seats while working in the chambers.
The goal is to provide the best port-match for the specific valve. "Hogging it out" is not the goal. The stock size port does not need to be enlarged very much to get good results, and too big of a port will cause a loss of port velocity and create unwanted turbulence. The goal is to reduce the restriction of the port.
Set the head in front of you with the intake flange facing you (right side up). The ports are round, and we are going to make them oval in the direction of the sparkplug holes, similar to a "V" shape. If you have a intake gasket or pattern to borrow, now is the time to draw/scribe it out onto the intake flange. Hold the grinder perpendicular to the flange and open up the ports to the new port shape. Don't worry about blending into the port yet. Take your time and make all the port openings look the same.
Set the acorn file out as far as you can in the grinder to give maximum reach into the port. On most heads the port has a casting part line right above the intake guide boss. This part line makes for a major corner right above the guide boss blocking any flow trying to go over top of the guide. You will want to blend this corner away by plunging the grinder down through the port going over top of the guide boss. Once through, work from the chamber side of the port to blend the contour. There is a fair amount of metal to remove here so take your time and study the port closely. The goal is to make the port above the guide look like it does below the guide, in effect straightening the port. This will open up a new flow path for intake charge. I also like to thin the intake guide boss, as it does very little anyway. Shape the metal into a nice teardrop shape around the guide, working from both ends of the port.
Once the major porting has been performed, blend the whole port together, removing all the bumps and corners, radiusing the port into the new openings. Use your finger to feel for irregularities. The contour should be one nice smooth blend all the way to the valve seat. Work slowly!
Exhaust Ports
I pretty much go by the book here. Without removing too much guide boss material, I like to contour the boss much in the same way that we did the intake bosses. Because the boss takes up so much of the port in that area, it helps flow to widen (or squeeze) the port around the boss. Working from the seat side of the port, start widening the port on either side of the boss just below the seat. You can blend these wide pockets into the port from the exit flange side. There is a sharp edge on most heads on the inside radius of the port, and it is almost impossible to see (you have to use your finger to find it). Tighten-up the inside radius, leading away from the seat, blending this edge away. Do not take too much material away here or there will not be enough left to support the seat properly. Lastly, open up the port at the header flange. Use an appropriate size exhaust gasket for this pattern.
What is Head Porting? ( All you need to know before you begin)
Parts of The Port
Basic Cylinder Head Porting
Porting How-to
Head Porting At Home
CC'ing Your Heads
Valve Shrouding
If you don't feel like doing your own Head Porting. There are Companies out there that will. ( If I;m forgeting someone just add as you go)
Comapnies:
http://jgenginedynamics.com/JGE%20main%20page.html
Videos
Cylinder Head Rebuild
Wet Flow Test
Port Flow Turbulence Test
Pictures
From:Combustion Contraption
^love this guys work
Comment