Porting header flanges?
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From: Traverse City, MI
Porting header flanges? Has anyone here ported a set of headers at the flange to clean up the welds inside the tubes? I know this obviously varies from header to header, but if you have, did you typically add material via welding on the outside of the tube/flange, or did you just grind down the welds inside and try not to break through? Just wondering because it looks like I could just grind them as they are now without breaking through, but I wonder if that would cause the header to crack in that area since it'll be thinner.
Mainly just curious if anyone's done this and had the header tube crack at the flange before. The welds inside the tubes are obstructing the exhaust flow. The flange opening is correct for the exhaust port, but the weld narrows this down a fair amount.
Mainly just curious if anyone's done this and had the header tube crack at the flange before. The welds inside the tubes are obstructing the exhaust flow. The flange opening is correct for the exhaust port, but the weld narrows this down a fair amount.
i did it on my super comps to get the ports to line up and transisiton correctly after AI ported my trick flows........i welded on the outside of the tube/flange then ported the inside......they were still too small though for my 385 i just sold em....
I have done this to every set of headers I have ever owned, even on my fox mustang. You will be 100% fine, grind away.
FYI: I use a small die grinder and a couple carbide bits. you wil be fine without extra welds, i have never had to weld extra
FYI: I use a small die grinder and a couple carbide bits. you wil be fine without extra welds, i have never had to weld extra
who's headers are you running now?
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prbly isnt worth much at all. but im a firm believer that if you do every little thing that you can, you will be a fender ahead of the guy in the next lane with the same setup.
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Verdad Gallardo ^ I agree 100%.......i just did all those little things to this setup.......hell i even knife edged my throttle body blade
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From: Traverse City, MI
I'd be doing it because, best I can tell, the welds are overhanging the port a little bit. Although I do agree with the theory of doing all the small things can only help.
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IMHO it would depend on whether or not the weld was blocking the exhaust port on the head. If so then yes by all means clean it up. This also goes for the header gasket. That also needs to be checked. No blockage of the head exhaust port is allowed. 
The headers that the author was working on had a fair amount of port mismatch on 3-4 of the ports. While on a couple of the others, he was able to do just a little grinding on the inside of the flange to get the ports to match the template he was using. On the "bad" ports, he had to build up the outside of the flange/pipe by welding, in order to give himself some material to grind into.
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I found the article in case anyone is curious:
http://www.highperformancepontiac.co...lds/index.html
Their idea for template making is useful, going to use it myself to verify just how much material I need to remove. Otherwise, everything is pretty basic, but the article is great if for no other reason than to show how important it is to verify this before bolting up a set of headers, especially with ported heads. Personally I went through several sets of headers trying to find ones that I liked that matched up with the ports on my heads, and even in the end I decided I needed to grind a little, hence this thread. As mentioned, the LPP headers fit great with respect to the flange opening interfacing with the exhaust port, unfortunately they were going to require too much clearancing to fit my car. Before anyone says it, I know the usual fitment problems with those, and mine were much worse than others. I'm certain it must just be my car because the previous owner of the headers said they fit great in his car and required very little clearancing.
http://www.highperformancepontiac.co...lds/index.html
Their idea for template making is useful, going to use it myself to verify just how much material I need to remove. Otherwise, everything is pretty basic, but the article is great if for no other reason than to show how important it is to verify this before bolting up a set of headers, especially with ported heads. Personally I went through several sets of headers trying to find ones that I liked that matched up with the ports on my heads, and even in the end I decided I needed to grind a little, hence this thread. As mentioned, the LPP headers fit great with respect to the flange opening interfacing with the exhaust port, unfortunately they were going to require too much clearancing to fit my car. Before anyone says it, I know the usual fitment problems with those, and mine were much worse than others. I'm certain it must just be my car because the previous owner of the headers said they fit great in his car and required very little clearancing.
