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Author
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Topic: Head porting question
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stang106
Gearhead Posts: 786
From: God's Country!... Port Alberni B.C. Canada
Registered: Jul 2001
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posted 04-14-2002 01:42 AM
   
After narrowing the guides on my new World Jr's and cleaning up the casting, its apparent that the intake long radius is formed in a smooth curve. So why do all the performance porting books and articles I've read deepens the intake long radius turn and disrupts this smooth curve? I am after good mid-range velosity here as opposed to higher top end flow. Do these deeper ports work better with top end only or also at 2,500 - 5,000 RPM?
Thanks,
Dave
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stang106
Gearhead Posts: 786
From: God's Country!... Port Alberni B.C. Canada
Registered: Jul 2001
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posted 04-17-2002 03:26 PM
Anyone? John? Kid? Mike? Alex? Or is this a little known area? From what I know, some ports do flow better with the long radius turn on more of an angle, depending on valve angle. Should I phone World Products with this? Thanks,
Dave
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JCQuinn@work
Gearhead Posts: 935
From: Lakewood, CO, USA
Registered: Jun 2001
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posted 04-17-2002 04:10 PM
Dave
I didn't answer this before because I have no experience with the World Jr's.I have read a lot of the theory books and they seem to make sense but when flowing heads I have noticed that the air flow at seems to skip across the top of the valve and the majority of the air enters the cylinder at that point. I experimented with different port flow shapes and did not make a significant difference in the flow pattern. To clarify, skipping across the top of the valve means entering the cylinder on the side of the valve that touches on the port roof radius. The majority of improvement that I found using stock castings came from using larger valves, removing the ridge between the machined area below the valve and the port cast surface, and minimizing the guide/valve stem area. Trying to significantly reshape the port floor never seemed to show large improvements. The most important feature of the port floor was trying to maintain a constant radius by smoothing out the ridge left by the valve pocket machining. Keep in mind all of this work was done on factory castings. I have been retired from racing for a long time and never worked with the modern aftermarket stuff. I definately would talk to the World Products people but keep in mind that you don't usually get to talk to the design engineers. John Quinn
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stang106
Gearhead Posts: 786
From: God's Country!... Port Alberni B.C. Canada
Registered: Jul 2001
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posted 04-17-2002 06:50 PM
Thanks John,
I'll give them a try after my last modifications, The other unknown-to me- is just how much cast material to leave on the port side of the exhaust 60 degree surface? Vizard seems to prefer to grind flush on the short side radius. I took mine to almost flush and blended it around. This is how I will try mine at the 1/4 for this year.
Dave
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 04-17-2002 07:49 PM
I didnt answer since almost all of my porting experiance has been on cleveland heads, and a few aftermarket sb chebbies. O just figured it is better to stay quiet than guess and give a wrong answer.
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stang106
Gearhead Posts: 786
From: God's Country!... Port Alberni B.C. Canada
Registered: Jul 2001
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posted 04-17-2002 09:23 PM
I wasn't trying to guilt-trip you guys-no need to explain why no answers. I had thought that there may be general "dos and don'ts". You guys have been-there-done-that and I am attempting to learn the easy way, not from expensive mistakes. As always, I appreciate the tutorials I read from all posts. I do know that port design can vary depending on the application, so what may work well with an all out race application may not apply to mine.
Dave
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 04-17-2002 10:22 PM
http://www.sa-motorsports.com/diyport.htmHere's a good guideline for porting, along with plenty of pictures. It should be just about right for those WP heads. Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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SundanceKid
Gearhead Posts: 1274
From: UT
Registered: Feb 2001
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posted 04-19-2002 03:30 PM
You want the short side radious as big and long as possible. That is what the windsor's are trying to accomplish. The books you have read more then likely are trying to remedy a less then ideal port shape to make it flow better at the top end with little reguard to low lift flow and velocity. When I port heads I will only clean up the casting flaws and make a smooth transitions on the port floor. Other then that I don't touch it! If you flatten the short side curve you will only hurt flow. The long side radious is less criticle to velocity and more criticle to high valve lift flow. The only reason I can see to deepen the pocket would be if it was the smallest point in the port and to open it up to match the valve and to lessen the restriction. Again probably to fix a less then ideal port. A better way to fix the problem would be to widen the port to one side making the port larger and aid swirl. But again this is an imperfect world and water passages always try to take up the same space as your ideal port wants! LOLHope that helps some [This message has been edited by SundanceKid (edited 04-19-2002).]
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Daniel Jones
Gearhead Posts: 898
From: St. Louis, MO
Registered: Aug 99
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posted 04-19-2002 04:53 PM
You might want to check out Vizard's article on porting the Windsor Jr's that was in one of the recent Mustang magazines. Forget which one but it was within the last couple of months.Dan Jones
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