Hey guys, just doing some practice porting on some old junk irons and i have a few questions. First of all this is just the rough cut, only using a carbide bit, i still have alot of stone grinding and sanding. I want to know if i should smooth out the coner transition from the runner to the port as indicated in the pic, and also if i should smooth out the roof out the outer edge. for my first port i think its turning out ok, I was amazed at just how fast you can port with an air die grinder and a double cut carbide bit. and its my understanding that I shouldn't change the size of the runner, is this true?

Thanks, Matt

 

You should pay just as much attention to the port runners as you do to the port opening itself. Having a whopping big port and small runners really hurts flow. Ideally they should have the same cross sectional area. I paid particular attention to the opening edge of the port and removed some of the radius where it blends into the runner so the airflow has more of a direct shot into the engine.

 

Have you spent any time in the 'Engine building and porting' section at NoPistons? You will find more info than you can digest in a week over there. Best source for porting there is.

 

^ what both of those guys said.