Here's where things get interesting. It's way more critical that the intake bowl be 85% of the 1.94" valve than on the exhaust side. The magic number in this case is 1.649". I still didn't have a caliper to measure with so I improvised by using the 1.6" exhaust valve. As you can see to the right it didn't fit at all. It wasn't really even close. Unfortuantely I discovered that to make this port the size i needed it I had to work on the short side radius. If I hadn't, the radius would have protruded into the bowl abnormally creating a flow restriction. If you wish to do this, you will have to make sure to smooth out this area after the cutting. I tried to maintain the original shape.
Left: This is more like it. The valve fits easily with a bit of room to spare. You can really see that I'm no pro by the not quite uniform appearance of the seat now. It shouldn't make more than a couple of CFM difference per port unless there's a MAJOR difference somewhere.
Above is an intake after the carbide burr but before I did a final cleaning up with the cartridge roll.
Below is an intake bowl after cartridge roll cleanup. I didn't have any way to show these ports without the shavings left in them.
GT40P Heads
Larger Valves
