The biggest issue with the early castings is that huge guide in the way and all the bias. I have to go out and grab my heads and look them over.
I never leave the guide boss that big, and I never leave the back side of it square. You almost never see any gain on the bench cleaning it up, but the port gets much more quiet, and that means more to me than what the manometer says.
I have to go back and look at your pictures, but if you can get the top cut .100 wide, do it. It should be .060 minimum. Some guys call that “sinking” the valve, but I call it the valve job. The top cut is HUGE. On both valves.
The top cut should really be 35* rather than 30*. And blend that top cut off smooth to the chamber.
If you are going to use a 45* seat, you really need a 3rd angle under seat. You can do it with two, but they have to be pretty wide. Look for a cutter that is 10* between the angles. 15* is a huge bend, and air hates that. Never, ever radius the intake valve job. Ever. And I never use anything but a radius on the exhaust.
If you can get the throat to 90% and still get a decent valve job on there, you can do that.
If you have a sonic tester, check very close around that short turn. The short turn is pretty crappy on the early castings. Do what you can.
FWIW, the W2 can flow less than the SM or any other standard port head and still kick its *** on HP. The port shape matters much more than the flow. Shape, shape, shape.
Also remember that what looks good at 10 inches can look sucky at 28 inches and then look real good at 42 inches. Play with the pressure drop and take detailed notes. And again, I can’t emphasize this enough, LISTEN to the port. A noisy, snapping, popping port is a power KILLER, even if it flows more. Believe that. Whatever you do, pay attention to the sound of the ports, and while I’m thinking about it, do NOT a make the mistake of porting the exhaust by the flow numbers. You will surely kill horsepower so fast your head will spin. In act, rather than use the valve job to get the throat out to 92% or so where the exhaust should be, use a 1.550 valve, or cut down a 1.600 valve .025 or so at a time until you get the throat to 92%. Make that port as quiet as you can.
Don’t be afraid to use a piece of string in the port to get a visual of where the air is going and what it’s doing. You can see dead spots in the port. Get some modeling clay and fill in the dead spots. The port will start getting less noisy.
Don’t forget to spend some time in the chamber. Do NOT take the chamber out past the cylinder bore. In other words, don’t take the chamber out to gasket size. That is another one of those places where the flow bench will love you for making the chamber bigger, but it’s a power loser.
1 inch in either direction from the valve seat is the most critical areas. Like I said, that includes the chamber. Again, it’s about shape.
Almost forgot to mention how critical valve shape is. Almost always a mail head will look better on the flow bench, but it’s almost always a power loser. Put the valve in the guide and visualize the venturi you are creating. That shape is a big deal. Shape shape shape. A nail head valve almost always wrecks the venturi shape. You can use clay on the valve to change the shape of it to see what happens.
One other thing I do is take the valve and stick it in the head from the rocker side and flow the port. See what you get when the valve isn’t in the way, and how that changes the flow and the sound.
There really isn’t a wrong way to test. Test everything. If you get some dry ice and put it in a cup with a straw and you can add a little water and get some good smoke. Hold the straw all around the port and see what you see.
I tried that with cigarettes. Burned the crap out of my fingers. Even at low lift, a cigarette will last maybe, maybe 5 seconds. Then your fingers will get toasty. Then I tried small cigars, with the same result. It just bought me a bit more time before the burn.
String, pencils, some TIG rod...whatever you can find can be used in a port to help visualize what you are doing. Some of this stuff is just counterintuitive so you have to test. You can use a piece of string and if you do it just right, you’ll find some exhaust ports that flow air in BOTH directions!!!
Harold Bettes has a picture of that in his book on airflow. Read all that you can, and then test what you read. Test test test and shape shape shape.
