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Discussion Starter · #1 ·
Hi,

I have some headers with a .31" flange. The height of the tube is fine, but the width is about .22" on the caliper narrower than my head exhaust port. Would wiser minds than mine leave it alone or would you be apt to kind of porting or grinding a bit to widen it on the flange or is that just asking for trouble?
 

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I say go for it. My repro iron exhaust manifolds had a big lump inside for AIR bosses and looked restrictive. I carefully ground them down, don't know if it helped but it didn't hurt, and made me think I picked up a couple HP.
 

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hi
sell them and buy headers that have good port matching .
Some have the primary pipe swaged /expanded where it meets the header flange plate .
I now select headers with the gasket that is the closest match to head exh port and header flange plate .

I also learnt the hard way . Thankfully the ceramic coated had a faulty coating rust spots etc so I returned them .
What I did not mention was the primary pipe overlap was real bad .

Better headers are available but hard to find .
Also consider adapter plate headers .1 3/4 and 1 7/8 I personally use 1 7/8 adapter plate on a 400 sbc
 

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Discussion Starter · #6 ·
they are 1 5/8 headers and going on afr 210 heads. the exhaust port on the heads is 1.52w by 1.4 tall. the engine may make 550hp if i'm lucky, probably closer to 500, i thought 1 5/8 is the right size for that power output?
 

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they are 1 5/8 headers and going on afr 210 heads. the exhaust port on the heads is 1.52w by 1.4 tall. the engine may make 550hp if i'm lucky, probably closer to 500, i thought 1 5/8 is the right size for that power output?
Nope, most would consider 1-3/4" the smallest for that kind of output, with some stepping up to 1-7/8" if they are chasing upper rpm HP numbers.

1-5/8" is done at about 450 hp level, above that you need bigger tubes.

AFR would not have put that big exhaust port on there if it wasn't needed for the power output they expect those heads to make.
 

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hi
Original headers were 1 3/4 overlapped exh port terribly . A well designed set does not . On a Afr Eliminator 195 Competition port . Adapter plate 1 7/8 fit well to port .

If your dealing with a second rate company they will still be using chev stock double hump heads as a reference .
 

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Discussion Starter · #10 ·
A lot of you gentlemen bring up some solid points. I will look into getting 1 3/4" headers that fit my application. Thank you. I'll be selling my 1 5/8s once the install of the new is complete!
 
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