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Author
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Topic: Hey! Measure your headers! Surprise!
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ukracer
Gearhead Posts: 151
From: South Wales UK
Registered: Apr 2003
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posted 11-25-2003 03:45 AM
   
OK, so I am messing about with Engine Analyser (it's dark and cold here) and I am tinkering with header sizes and not really getting very far when I decide to measure the pipe size on my headers. Sold to me as 1 5/8" Flowtechs bit I'm thinking OD or ID? Guess what? Get the calipers over the pipe (on a straight section) and it reads 1 1/2" OD! Aargh! Teeny Tiny pipes on my 351 which EA says is not good. Anyone else here measured their pipes or do you all just trust (like I did!) and what size would you recommmend for my 351W? Quick spec:
1969 351W, +.030, 9.5:1, C9 heads ported, Ebrock RPM intake, CCXE268 cam, 600 Holley, Flowtech headers as above. Always run with full exhaust system (straight through boxes) and car is 69 Fastback/toploader. TIA
Cheers, Martin.
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Moneymaker
Administrator Posts: 25883
From: Lyons, IL, USA
Registered: May 99
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posted 11-25-2003 10:30 AM
Forget the EA man. 
Those headers will work GREAT with your particular combo Martin. You don't have enough cam, carb, or compression to utilize any more primary size anyway.
They will give you fantastic low end torque and throttle response. Until you see 6000 + RPM, larger tube size won't be a power issue.------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,&'03
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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ukracer
Gearhead Posts: 151
From: South Wales UK
Registered: Apr 2003
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posted 11-25-2003 11:21 AM
Thanks Alex, now I can pretend I did this intentionally! You are right, it pulls like a train from tickover right through to about 5200 but that's it, no more then. I just wondered if these pipes are the restriction. 6000 is just a dream for me, it will never rev there. Now I am wondering if I should drop the collector size down from 3" to 2.5" (along with the X pipe) as I have on my 460CJ, which is very torquey AND revs happily past 6000. Weird science.
Cheers, Martin.
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Moneymaker
Administrator Posts: 25883
From: Lyons, IL, USA
Registered: May 99
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posted 11-25-2003 11:32 AM
Carb is the limiting factor, not the headers.------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,&'03
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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TomP
Gearhead Posts: 5761
From: Delta BC Canada
Registered: Dec 99
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posted 11-27-2003 01:19 AM
I had an early Bronco with a 351W with a bigger cam and carb and more compression than that and 1 1/2" headers were all you could get to fit it, worked fine to valve float speed (and that sure happened way too often  )
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