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Porting specifics, porting transition from runner?

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Old 04-13-06, 02:22 PM
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Question Porting specifics, porting transition from runner?

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


Old 04-13-06, 06:56 PM
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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.
Old 04-13-06, 08:34 PM
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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.
Old 04-13-06, 09:54 PM
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^ what both of those guys said.
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