Need new Carburetor for 454 - Impala Tech
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post #1 of 11 (permalink) Old 05-07-2010, 12:29 AM Thread Starter
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Need new Carburetor for 454

Like the title says i need a new one. I have the original Quadrawhatever, its a big ball of rust. The last owner tossed a Holley of some sort on it and it seems to have a lot of build-up on it, and a few leaks. My friend said i could fix it up but i think i am just going to get a new one and start fresh. Any recommendations? i don’t plan on adding much performance to it in the future other than some headers and a new flow master exhaust.
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post #2 of 11 (permalink) Old 05-07-2010, 01:32 AM Thread Starter
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I think i am going to get this guy:

http://www.amazon.com/Holley-0-80770-4-Barrel-Secondary-Carburetor/dp/B00029J4JC
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post #3 of 11 (permalink) Old 05-07-2010, 08:47 AM
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When it comes to carburetors everyone has their own opinions as to witch is best. If you want to keep it original ,have the original one rebuilt at a reputable shop , Or find a replacement that doesn't require changing all the hookups.

http://www.impalas.net/forums/image.php?type=sigpic&userid=521&dateline=14693626  69
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post #4 of 11 (permalink) Old 05-07-2010, 09:05 AM Thread Starter
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The original can not be saved... it's beyond gone. I just want to make sure i'm not getting one to large or to small.
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post #5 of 11 (permalink) Old 05-07-2010, 09:22 AM Thread Starter
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Pictures of original (phone pics):







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post #6 of 11 (permalink) Old 05-07-2010, 10:39 AM
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A 750 or that 770 will be fine. On a mild engine, the vacuum secondary is the key. A mechanical secondary will flood and choke the engine when you dump the throttle. The vacuum secondaries open slower. That's what I use on my mild big blocks and they work fantastic. Great power and 12 miles per gallon. Who could ask for anything more??!!

Don't listen to me, what do I know? I've only been doing this for 30 years.
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post #7 of 11 (permalink) Old 05-07-2010, 12:30 PM
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Do you have a spreadbore or squarebore intake? That will help in choosing a bolt on without using adapters that may give you hood clearance issues. If you can, take a pick of the top of your intake manifold.
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post #8 of 11 (permalink) Old 05-07-2010, 08:57 PM
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I would assume since the original owner swapped the Rochester 780 cfm Quadrajet over to a Holley (most likely a 750 cfm vacuum secondary, but it might have been an 850 as I have seen a lot of both on top of big blocks). Since the Rochester didn't get to look like that on top of the car I assume it rode around in a very damp trunk for a while (the white stuff is oxidized aluminum which will leave pits when cleaned off, but even in this condition it can be rebuilt and restored to life). I also assume the Holley on top of the BBC runs now and has been dragging the Quadrajet in the trunk through a lot of car washes.

If the Holley on top of the motor now has a dual feed cathedral fuel bowl set-up then I would rebuild the Holley you have now (Holley's are as popular as they are for their ease of maintenance and tune, not because they work any better than any other brand of carburetor). You can field strip one to a basket full of parts (to be cleaned in carb cleaner naturally) in a matter of minutes and with nothing more than an exploded view diagram of where the parts go reassemble one for the first time in about a half an hour. If you bother to read the instruction sheet (few do) you can tune the Holley to fire right up and purr like a kitten after the rebuild as all of the tuning instructions are on the rebuild instruction sheet.

Big Dave
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post #9 of 11 (permalink) Old 05-07-2010, 09:33 PM Thread Starter
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Thanks Dave,

I ordered a Holley 770 street avenger today. I have pictures of the Holley i currently have. i might just cancel my purchase and keep the current Holley.

Here are the pics:











I see a lot of black build up... I might try to find a place that can rebuild it i am just tired of waiting and i wanted to have this running for the wife on Mothers day =(.
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post #10 of 11 (permalink) Old 05-08-2010, 05:22 PM
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The carbon build up on the throttle plates doesn't bother me as much as the rounded off inlet tube adapter nuts. Means some Holley expert got a hold of it and didn't have the correct size wrench to loosen the nut or tighten it. I see you are using an adapter plate beneath the carb with a Rochester Q-Jet adapter on a 454 TBI manifold. A better allocation of your limited funds instead of a new carb would be a Holley carb rebuild kit ($40), and a tub of carb cleaner with parts tray ($30), and a new aluminum intake manifold for a round port head (I have no favorites so I will let others speak up about what is the "best" manifold out there). No mater which you buy it will be better than what you have and a lot lighter.

Big Dave
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post #11 of 11 (permalink) Old 05-08-2010, 07:49 PM Thread Starter
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Thanks a lot Dave for the advice.

Today after work had another mechanically inclined buddy stop by and help me out. We cleaned out the carb best we could, he then made a few small adjustments. The car when from underivable due to the low end bogginess and lack of acceleration. To running almost perfect with a small bog here and there... it really came to life. I will be returning the new carb when i get it, and doing what you mentioned. It took us 20 mins to get the car going great i can't imagen if i pull the carb off and clean it out how it will run.

I also got a new fuel line the metal part that attaches to the carb since the old one was stripped like you said.
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