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Carb choice HELP

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Carb choice HELP

Post #1 by 65-coupe » Fri Jul 12, 2013 9:27 pm

Engine specs, CI alum head and intake(port, polished and CC for a 9.5 C/R)
1.65 roller rockers
264/264 110 Cam advanced 4 degrees
DUI recurved my Faron
Headers 2" exhaust with X pipe and Impostor mufflers
Stock botoom end

Well I am running a 2100 300 CFM right now. I have tried jets from 48-54. With all the jets it bogs down when I floor it and A/F goes to 16-18. Ideals great, cruise A/F is about 14.5, When I floor it will going A/F is about 12. I am thinking of having a 2100 CFM rebuilt or buy a 390 or 465 Holley 4bbl. IF I go with the Holley not sure which one. I talked to two guys from Holley and both said go with the 390. Could it handle the 465 I know Mraley used a 4100 with 480. any help would be great. Brian
1965 Mustang coupe, Poppy red with black interior, I6, DUI, CI alum head ported, 264/264 110 Clay Smith cam, 1.65 roller rockers, Autolite 2100 300CFM, Lokar pedals and throttle calbe, Spectre air intake. Shelby mod to front suspension, CI headers stainless with Jet-Hot ceramic coating, CI Stainless 2" impostor dual exhaust, 17x8 Coys C-67 wheels,

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Re: Carb choice HELP

Post #2 by 80broncoman » Sat Jul 13, 2013 12:27 am

A word of caution on comparing 2 bbl and 4 bbl carbs,
There is another thread on here where Frenchtownflyer and myself point out that 2bbl carbs and 4bbl carbs CFM units of measure are taken at different pressures. (A 300 CFM 2bbl does NOT equal a 300 CFM 4bbl carb)

The example that sticks in my head is this:

A model #3310 4 bbl Holley is a 750 CFM carb It has Exactly same size front half and rear half.

A model #4412 2 bbl Holley is a 500 CFM carb This carb is Exactly the same size everything as the front half of the #3310 4bbl.

So if you measure the 500 2bbl carb at the same pressure drop as the 4bbl it is then a 350 CFM instead of the 500 rating.
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80 bronco FUV (farm utility vehicle)300 T-18 3.50s EFI head, offy C dual plenum, 500 edel carb, 1.7 roller rockers, Crane 260 cam EFI Exh

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