what carb should I use ? - Pontiac GTO Forum
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post #1 of 3 (permalink) Old 02-22-2016, 09:06 PM Thread Starter
 
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what carb should I use ?

Ive just completed a 2 year restoration on a 68 400HO 4 spd and need advice on what carb to use. The previous owner rebuit the motor with a 520 lift cam (not sure of the duration) and installed a dual plane alum intake with headers, and ported the heads ,the car has a pretty lopey idle. The carb is only a 650 cfm holley which seems pretty small I'm thinking I need at least a 750 cfm to be in the 450-500 range. Ive welded o2 bungs in the collectors to hook up my a/f ratio gauge to tune the carb if needed I just don't want to drop $500 on the wrong carb I would even consider a used carb any advice would be appreciated.
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post #2 of 3 (permalink) Old 02-23-2016, 11:23 AM
 
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In my opinion you would be hard pressed to do better than the original Quadrqajet.
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post #3 of 3 (permalink) Old 02-23-2016, 11:36 AM
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The original Q-jet, jetted and metered for your engine, would be the best performer. If that is not an option, yes, a Holley 700 or 750 would be helpful. Your 600 is on the small side for optimum top end performanc.
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

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