 Velocity Stacks |
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| neyen14 |
 Nov 6 2025, 07:42 PM
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#1
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Member  Group: Members Posts: 85 Joined: 2-December 07 From: New York Member No.: 8,408 Region Association: North East States  |
I am using dual Weber 40 IDF's. 96mm cylinders c35 scat cam
#1 The Original "velocity stack" is a straight shot down the throat of the carb. #2 Shorter shinier velocity stack is for 40 - 48 IDF and leaves about a 1/8" lip at the top plate of the carb #3 The taller less shiny velocity stack says it is for DRLA & IDF 36 - 40mm but leaves about a 1/16" lip at the top plate of the carb I started to widen the inside of the #1 Original and thought it better to have a straight shot down the throat then it would be to have any bit of a lip.... however, I was recommended to use the non original velocity stacks and don't worry about the lip, they've "found it doesn't affect performance".... which seems counterintuitive to the ideas of porting, polishing, and general flow etc 1. Do you think opening up the original velocity stack and having the straight shot is worth it? 2. Should I not worry about the lip? 3. Is there a stack that would fit the 40 IDF specifically without covering a range? Attached thumbnail(s)     
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| Jack Standz |
Nov 7 2025, 03:24 AM
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#2
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Senior Member Group: Members Posts: 578 Joined: 15-November 19 From: Happy Place (& surrounding area) Member No.: 23,644 Region Association: None 
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There are at least two different diameters on venturis for IDF carbs, so there might be velocity stacks with different diameters. See if your favorite carb vendor can set you up. (IMG:style_emoticons/default/smile.gif)
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| neyen14 |
Nov 7 2025, 05:43 AM
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#3
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Member Group: Members Posts: 85 Joined: 2-December 07 From: New York Member No.: 8,408 Region Association: North East States |
QUOTE(Jack Standz @ Nov 7 2025, 01:24 AM)  There are at least two different diameters on venturis for IDF carbs, so there might be velocity stacks with different diameters. See if your favorite carb vendor can set you up. (IMG:style_emoticons/default/smile.gif) Good morning! Thx you Mr. Standz (IMG:style_emoticons/default/lol-2.gif). I think I'm all set with the venturi at least until I see how it runs. The issue is the area well above the venturi. It was the vendor that told me not to worry about the lip created by the wider inside diameter velocity stack (I tried to show in these picture). The stacks seem to be only sold like a one size fits all 40mm -48mm or 36mm - 40mm..... same with the air cleaners now that you mention it lol Thank you |
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Posts in this topic
neyen14 Velocity Stacks Nov 6 2025, 07:42 PM
neyen14 Here's an above view with each Nov 6 2025, 08:53 PM
Jamie
Here's an above view with each
The flow dyna... Nov 7 2025, 07:42 AM stownsen914 You don't want to have a ledge/lip at the velo... Nov 7 2025, 09:01 AM neyen14
You don't want to have a ledge/lip at the vel... Nov 7 2025, 09:42 AM neyen14
Here's an above view with each
The flow dyn... Nov 7 2025, 09:35 AM Front yard mechanic Can’t you get taller air cleaners and use the ta... Nov 6 2025, 09:13 PM neyen14
Can’t you get taller air cleaners and use the t... Nov 7 2025, 01:40 AM |
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