Pics of my ported shortie headers
 

Just removed my ported Mac shortie headers and I'm in the process of porting and installing Hooker 1 3/4" to replace them. Thought you might like to see what I did to run a 10.65 et with shortie headers. These worked great on my 302 but this 347, I feel, needs a little more flow than 1 5/8" headers can handle. But that 10.65 is not too bad.
The first pic shows the weld I made around each head port. Notice how each port has been heated and the dimples pushed out. I had to use Allen bolts for clearance but they work great with a ball end Allen for wrenching. Second shows an enlargened port and all weld buildup removed. It is still strong with the outer weld. Third is the porting I did to remove the weld build up in the collector.
http://www.fbody.com/members/LarryS/shortweld.jpg http://www.fbody.com/members/LarryS/collport.jpg http://www.fbody.com/members/LarryS/collgrind.jpg


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88 347, Twisted wedge heads,Comp Cams 224/230 cam, 1/4=10.718 @ 123.02 mph