I wouldn't think it would be too much for a tappered flange.

 

SS doesn't machine well in a situation like you are proposing. It's kinda like cutting cheese and is really hard on cutters. And with interrupted cuts with a fly cutter or a surfacing tool, its going to be tuff to get a good finish and keep the cutter sharp for the whole cut.

Your best bet would be to use just a 1/2 flange and stack it if that would do want you need. Colombia River Mandrel Bending sells them. A MS steel flange would be MUCH easier to machine like you want if that's the way you want to go. It could still be welded to the SS flange with 309 tig rod but I would proable stack them as there is less warpage.

 

Might be way easier to just use 2 gaskets and a mild steel flange as a spacer between the gaskets.

Cheaper and easier to machine, and you don't screw up the headers.

 

Could give these guys a try on getting a tappered spacer/flange. I have used there stuff in the past and its been very high quality and they have been great to deal with.


Also ran across this guy. He makes them for some sidelines but might be blue to make them for the header as well. Worth a shot.
http://www.breezeautomotive.com/deta...=719&cat_id=26

 

I have a set of ARH flanges on the way. I'll do this myself with an angle grinder

 

1/2 wouldn't move collector enough, and it would also put my primaries into the steering box. I've thought about it.

 

I dropped the flanges with the machine shop today. one guy was excited to figure out how to make it happen, and the other guy was shaking his head saying it's going to be a PITA.

if the offset works, we plan to weld the flanges together and machine down the weld for one single wicked thick flange. then we have to put a flat face on the header flange to offset the bolt head sitting on an un flat surface. I have confidence in the guy doing the work. I've seen him repair some FUUUUUCKED up heads in the past. Ask skeet. his was one of them lol.

 

hopefully they get it figured out. Welding them together is a good idea, if there stainless you could just fuse weld them and be good. as far as drilling the holes flat you should just be able to set them on the table, flange down, and use a long endmill to to flatten out the hole since it will be parallel to the flange that way.

post some pics when you get them

 

The tapered flange is also going to change the angle of the bolt channel. Assuming a .25" rise on a 18" run presents a .79* angle. Transferring this angle to the bolt hole on the large end of the tapered flange (0.875") moves the hole over 0.012" and 0.008" on the small end (0.625). This may present an alignment issue. You may have to redrill the holes perpendicular to the new head/flange surface then angle counter sink the bolt head side.

 

that's some pretty exact math you have there...wish i had the knowledge or tools to look that far ahead. all of the bolt holes on the ARH flanges are slightly elongated. hopefully that gives enough room. if not i can get the holes drilled true. no biggy there. countersinking the bolt head side is in the plans too. step one is to see if the angle milled flange will put everything where i want it to be.

for anyone considering ARH headers...get Kooks IMO. i shouldnt have to spend another ~400 to modify my 1,200 $ headers. support from ARH has been lame too. Colorado speed on the other hand has been awesome.