rockmeupto125 Posted July 7, 2016 Share Posted July 7, 2016 I've been toying with the idea of building up a naturally aspirated engine. Any of you hot rodders have some recommends for cylinder head porting? I considered taking a stab at it myself as I half a couple spare heads and some half-assed ideas, but it might be better to work with a known quantity. Thanks! Quote Link to comment Share on other sites More sharing options...
ironmike Posted July 7, 2016 Share Posted July 7, 2016 Have you access to a flow bench? Head porting is almost as much an art as it is a science. You'd be wise to do some research before you start. FWIW, the XX heads (carb & FI) flow very well in the stock configuration. http://www.motorcycleproject.com/text/cows-porting.html http://dynobike.com/porting.htm Quote Link to comment Share on other sites More sharing options...
mikesail Posted July 7, 2016 Share Posted July 7, 2016 The first article by Mike Nixon is very good indeed. Pay attention to what he says about valve seats especially. There was an article recently about dimpling intake bores to look like a golf ball, claimed a dramatic increase in air flow. Quote Link to comment Share on other sites More sharing options...
rockmeupto125 Posted July 8, 2016 Author Share Posted July 8, 2016 No flow bench. And yes, its an art. Enough so that I'm not willing to ship it off to someone who says they do porting without some serious supporting evidence, including feedback from you folks. Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted July 8, 2016 Share Posted July 8, 2016 You could rig a 'flow bench' with a shop vac and vacuum gauge or a simple flow meter used to sync carbs. Won't give you CFM numbers but will give numbers to work with. You could start with just removing any sharp edges and blending the seats in, maybe back-cutting the valves; chuck it up on a drill press and grind/file while it spins. Been so long since I looked in a Bird head I don't recall if there were obvious easy things to address. Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted July 8, 2016 Share Posted July 8, 2016 I bet Northman knows since he built a non-turbo big motor. Quote Link to comment Share on other sites More sharing options...
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