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 FNG seeks IFR/IAB golden ratio 
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Joined: Wed May 29, 2013 6:12 pm
Posts: 33
In my limited experience, the typical "street" car with a conventional Holley style carb will function reasonably well with an IFR in the .028-.031 range and an IAB between .070-.073. But as a certain Unicorn wrangler once said "circumstances alter cases".


Thu May 11, 2017 5:12 pm
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The tricky part is to determine which portion of the Unicorn Horn to choose for the frustum calculation necessary to compare to the Pixie Dust Mote volume in order to find the ratio of frustum/frustration, which is useful for some bleeds in some cases if some circumstances are altered more than others.


Sat May 13, 2017 12:05 am
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Joined: Sat Feb 25, 2017 11:58 am
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In the absence of a readily available unicorn, can narwhal be substituted, or am I just stuck with a billy goat?

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Sat May 13, 2017 12:37 am
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Joined: Mon Oct 21, 2013 12:15 am
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Location: San Diego, CA
I wouldn't necessarily say that you are stuck with a billy goat. If all other options fail, I would opt for the geep.


Sun May 14, 2017 4:27 pm
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Rocky Mtn. Bighorn Sheep can be useful for Ram manifold calculations. The frustration arises in choosing the ideal frustum for L/D factoring.


Sun May 14, 2017 5:06 pm
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Joined: Wed Apr 03, 2013 8:06 pm
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Working with a Book carb on the dyno this week, it's a 2.19 bore, 1.9x something venturi dominator. Came from Book with .032 IFR, and .026 IAB (off the top of my head). Idles great, runs very clean for a 3 circuit, definitely not the norm for idle circuit config.


Mon May 15, 2017 11:58 am
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Location: San Diego, CA
Here is my take on carburetor math.


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Mon May 15, 2017 12:11 pm
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Joined: Fri Feb 08, 2013 5:50 pm
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JayCampbell wrote:
Working with a Book carb on the dyno this week, it's a 2.19 bore, 1.9x something venturi dominator. Came from Book with .032 IFR, and .026 IAB (off the top of my head). Idles great, runs very clean for a 3 circuit, definitely not the norm for idle circuit config.


26 IAB? On gas? It's not idle I would worry about, it's part throttle, 2000-3500 range.


Mon May 15, 2017 1:20 pm
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Joined: Wed Apr 03, 2013 8:06 pm
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jmarkaudio wrote:
JayCampbell wrote:
Working with a Book carb on the dyno this week, it's a 2.19 bore, 1.9x something venturi dominator. Came from Book with .032 IFR, and .026 IAB (off the top of my head). Idles great, runs very clean for a 3 circuit, definitely not the norm for idle circuit config.


26 IAB? On gas? It's not idle I would worry about, it's part throttle, 2000-3500 range.


That's from memory, Ill double check, but it only has an .032" IFR, it runs fine. Intermediate feed is .031, so fairly small as well. It has had the transfer slots bored and replaced so that may play into also. I was surprised, but It's been to drag week, will be doing drag week again this year, and I expect he can win the Hot Rod class as long as he doesn't have any problems. He had the field covered pretty well last year until he had a piston problem. .180" piston top thickness doesn't play very well at 15.5:1. I played with it on the dyno until 11:00 last night. I did a set of BLP wide body blocks for it so he could try some Q16. Had to go down to 92 jets from 97 with the wide body blocks, all else being as close as possible as the Holley blocks it came with (with Sunoco Maximal). Was making a solid 20hp more with Q16, but not going to have time to tune it the way he wants to, so we switched back to Maximal.


Tue May 16, 2017 4:16 pm
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Joined: Wed Apr 03, 2013 8:06 pm
Posts: 159
Ok, brain fart. IAB is .040, makes more sense. Sorry, was about 2 weeks ago when i probed it.


Tue May 16, 2017 7:05 pm
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