Header Question
 

Would 1 1/2" or 1 5/8" primaries be better for my sb400? I've heard that smaller primaries equal more torque, but wondered if 1 1/2" was too small for this engine.

Thanks

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71 SWB Stepside
Houston, TX

IMO, the 1 5/8" are the way to go on a 400. The 400 makes good bottom end torque already.

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"Fast Orange"
1972 Chevy Stepside that will one day be finished!!

My thoughts, too. I was going to get the coated Dynomax - they are a nice price, but I guess I need to look at Hooker or Headman.

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71 SWB Stepside
Houston, TX

If I was doing headers on the 400, I'd skip all the way to 1 3/4" tube.

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70 GMC 3/4 ton Sierra Grande 402/TH400
72 Jimmy 4WD 4spd 4" & 35's
64 Corvette Coupe
68 Camaro 'vert TPI & TH700
69 Z/28 355 12.6's @110
72 Datsun 240Z-ol' reliable

make sure you get good ones. I bought cheap ones and they leak very bad.

Im runnin 1 5/8 on my 383,you could go to 1 3/4,but i didnt feel it was needed on my street truck. If you are racing,the bigger pipe is the way to go........69