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Recommended Quadrajet 4bbl Carb Adapter

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Old January 17th, 2014, 09:20 AM
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Recommended Quadrajet 4bbl Carb Adapter

Does anyone have a recommended carb adapter for an edelbrock dual plane intake like the one below. Trying to place my current 750cfm quadrajet onto a square bore edelbrock intake. Found for single plane but not for dual plane intakes like the one below or does it matter?. Thanks

EDELBROCK RPM AIR-GAP OLDS 455 #7551 with 1971 Quadrajet

1969 Cutlass S Hard Top
455 ci

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Old January 17th, 2014, 09:47 AM
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Originally Posted by atkinsom View Post
Does anyone have a recommended carb adapter for an edelbrock dual plane intake like the one below. Trying to place my current 750cfm quadrajet onto a square bore edelbrock intake. Found for single plane but not for dual plane intakes like the one below or does it matter?. Thanks

EDELBROCK RPM AIR-GAP OLDS 455 #7551 with 1971 Quadrajet
The spreadbore-to-squarebore adapters are at best flow disruptions and at worst a significant detriment to airflow that can negate the benefits of a new intake. Much as I prefer the Qjet, I would recommend getting a square bore carb that matches the intake.
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Old January 17th, 2014, 09:52 AM
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X2 on getting a square bore carb. If your not planning on going to 6500 rpm, I would suggest a Perfomer manifold. An airgap and an adapter may not clear your hood.


Edelbrock makes an adapter:


http://www.edelbrock.com/automotive_..._spacers.shtml
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Old January 17th, 2014, 06:17 PM
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Thanks guys took your advice and did some hunting this evening since I don't want to mod the hood under any circumstances. I might be able to get my hands on a slightly used edlebrock 750 cfm square bore carb through a friend. You think i'd have any issue with hood clearance if I stick with the RPM air gap manifold and an edelbrock carb? Really like that air gap and trying hard to keep it. Thanks again

1969 Cutlass S Hard Top
455 ci

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Old January 17th, 2014, 09:00 PM
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If the Edelbrock carb has an electric choke, you may not be able to use your air cleaner without modifications.
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Old January 18th, 2014, 07:53 AM
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When you say mods I assume you're talking about the air cleaner assembly? Would a very low profile air cleaner assembly do the job over the stock air cleaner? Sorry for all the questions but I'm buying all the stuff in advance in the US and returning it after the fact is a pain. Thanks again
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Old January 18th, 2014, 08:06 AM
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All your questions are good ones. The electric choke may interfere with the air cleaner base not allowing it to sit flush on the carb. This can also happen with a lot of the aftermarket drop bases, and sometimes if you find one that fits it will sit too high and interfere with closing the hood. . I and a lot of others have gone through this. If you go with a Holley you will not have this problem.
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Old January 23rd, 2014, 09:20 AM
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Thanks for all the great info. I also notice with the rpm air gap that the runners are different. It sure looks to me that my factory brackets won't work right. I'm using A/C brackets and corresponding alternator brackets that came with the 1969. Anyone have any experience on what kind of mods would be required since I really don't want to butcher up my factory brackets if I don't have to. Can you buy brackets specific to that intake or do I need to prefab something up? I've looked and really don't see aftermarket brackets but maybe I'm missing something. Thanks.
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