Header Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mikej71 · 05-21-2002, 09:56 AM

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

Fast Orange · 05-21-2002, 10:09 AM

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!!

mikej71 · 05-21-2002, 01:25 PM

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

Mike C · 05-21-2002, 03:44 PM

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

misfits · 05-21-2002, 04:27 PM

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

69 longhorn · 05-21-2002, 07:44 PM

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

05-21-2002, 09:56 AM	#1
mikej71 Unregistered User Join Date: Dec 2001 Location: Houston, TX USA Posts: 538	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 ------------------ 71 SWB Stepside Houston, TX __________________ 71 SWB Stepside SB400/TH350

05-21-2002, 10:09 AM	#2
Fast Orange Registered User Join Date: Feb 2002 Location: Oklahoma Posts: 170	IMO, the 1 5/8" are the way to go on a 400. The 400 makes good bottom end torque already. ------------------ "Fast Orange" 1972 Chevy Stepside that will one day be finished!! __________________ Randy aka "Fast Orange" 1972 Chevy Stepside that will one day be finished!!

05-21-2002, 01:25 PM	#3
mikej71 Unregistered User Join Date: Dec 2001 Location: Houston, TX USA Posts: 538	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. ------------------ 71 SWB Stepside Houston, TX __________________ 71 SWB Stepside SB400/TH350

05-21-2002, 03:44 PM	#4
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,709	If I was doing headers on the 400, I'd skip all the way to 1 3/4" tube. ------------------ 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 __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

05-21-2002, 07:44 PM	#6
69 longhorn Registered User Join Date: Aug 2001 Location: rock island,il,usa Posts: 5,382	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 __________________ http://community.webshots.com/user/hotrodhorn

05-21-2002, 04:27 PM	#5
misfits Registered User Join Date: Feb 2001 Location: Sturgeon Bay , WI USA Posts: 375	make sure you get good ones. I bought cheap ones and they leak very bad.



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