225 Porting
I'll try and answer some of the questions. First of all, my experience with porting has been limited to some Chevy 283 heads I butchered back in the 70s, however I'm a fabricator and metal worker by trade.
When I decided to do this, I made sure of some things before I started. You must have the right equipment and tools. I read several "how to" publications. I spent a lot of time on "Uncle Tony's page on Youtube. You do have to be careful and go slow, yes it would be easy to grind through a water jacket. Exhaust ports need the most attention. Get rid of "casting edges" and flat surfaces. Imagine blowing air up against a flat, rough wall, as it will act like a dam and defector. Smooth (blend) those edges out, giving the exhaust gases a "slide board" to the outside. The intake ports can be opened up somewhat like the exhaust ports, but smoothness is not as critical, in fact the little bit of turbulence caused by a a small amount of roughness, actually helps mix the fuel and air prior to entering the combustion chamber. The exhaust ports, being smaller, requires a little more control of you tool, as not to accidently nick the valve seat. I found that can be avoided by using a good quality tape applied to the valve seat.
Addressing the valve seats...I did not have harden intake seats installed, but I did have harden exhaust seats installed. Why? Because I was told (by a slant guru) it wasn't necessary for the intakes, the exhaust valves are the ones that take the biggest beating. I plan on running "a little" nitrous also. I would recommend that if you are going to overhaul an engine made prior to the late 70s to install hardened exhaust valve seats. My machinist's invoice listed the valve job and install the seats at 325.00. The seats cost 6.00 each. Yes, I will be breaking all the edges on the combustion chamber and dressing it up some what. I still have some work to do on the manifold side of the head. Uncle Tony will show you how to gage the amount of material to remove, by using the manifold gasket as a template. Again, you have to be careful also, not to grind through a water jacket. On all of the grinding, you need to use lay out dye. I found that it soaks into the pores and when you grind away the dye (especially on the sides of the port) you have went far enough. I can't stress enough that you need lights, bright lights, lights in the ports, lights over head, lights everywhere. I still have 3 ports and some manifold side work to do, so screwing up is still possible. Do your home work, visit Uncle Tony on Youtube, and take your time. Go for it.
Norm
I'll try and answer some of the questions. First of all, my experience with porting has been limited to some Chevy 283 heads I butchered back in the 70s, however I'm a fabricator and metal worker by trade.
When I decided to do this, I made sure of some things before I started. You must have the right equipment and tools. I read several "how to" publications. I spent a lot of time on "Uncle Tony's page on Youtube. You do have to be careful and go slow, yes it would be easy to grind through a water jacket. Exhaust ports need the most attention. Get rid of "casting edges" and flat surfaces. Imagine blowing air up against a flat, rough wall, as it will act like a dam and defector. Smooth (blend) those edges out, giving the exhaust gases a "slide board" to the outside. The intake ports can be opened up somewhat like the exhaust ports, but smoothness is not as critical, in fact the little bit of turbulence caused by a a small amount of roughness, actually helps mix the fuel and air prior to entering the combustion chamber. The exhaust ports, being smaller, requires a little more control of you tool, as not to accidently nick the valve seat. I found that can be avoided by using a good quality tape applied to the valve seat.
Addressing the valve seats...I did not have harden intake seats installed, but I did have harden exhaust seats installed. Why? Because I was told (by a slant guru) it wasn't necessary for the intakes, the exhaust valves are the ones that take the biggest beating. I plan on running "a little" nitrous also. I would recommend that if you are going to overhaul an engine made prior to the late 70s to install hardened exhaust valve seats. My machinist's invoice listed the valve job and install the seats at 325.00. The seats cost 6.00 each. Yes, I will be breaking all the edges on the combustion chamber and dressing it up some what. I still have some work to do on the manifold side of the head. Uncle Tony will show you how to gage the amount of material to remove, by using the manifold gasket as a template. Again, you have to be careful also, not to grind through a water jacket. On all of the grinding, you need to use lay out dye. I found that it soaks into the pores and when you grind away the dye (especially on the sides of the port) you have went far enough. I can't stress enough that you need lights, bright lights, lights in the ports, lights over head, lights everywhere. I still have 3 ports and some manifold side work to do, so screwing up is still possible. Do your home work, visit Uncle Tony on Youtube, and take your time. Go for it.
Norm
