how to port and polish toyota 4k cylinder head? where should i start? intake manifold? 

any idea where to start?

Edited November 11, 20178 yr by KE70ph

Look up oldskewltoy and PM him for ideas, he does porting as a business, some amazing work!

Generally, buy the gasket you're going to use, measure that and the inlet manifold, and make all three diameters the same. Having an inlet manifold diameter smaller than an inlet port is no problem, that lip reduces the reversion back up the carb, but it pays to have a smooth tunnel all the way to the valve.

You can see the gasket I used here-

https://www.rollaclub.com/board/topic/42407-the-girls-ke70/

The port size depends on the cam and the revs you will use, overall larger ports flow slowly at low-medium revs and don't fill cylinders very well. I have them larger at the gasket than the valve because the velocity of the air increases as the diameter narrows so it retains inertia going past the valve.

Make sure the casting around the back of the seat is smooth and continuous with the seat, and the same as the seat merges into the combustion chamber.  The inlet is the important one, the exhaust gets pumped out.

The downdraught carb is a pain if you're using that, the air has to turn that 90deg bend under the carb.  All you can do is smooth any sharp edges & corners from machining the casting in the factory. A single Weber DCOE makes a much better job of it.