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I'm sure this question has been asked dozens of times, but I'm a new guy so please go easy on me. I have a virtually stock 289. Only mods. I have done is electronic ignition, headers, 2 1/4 exhaust and AOD. Plan to but in a cam ,but no major internal modifications to the engine. My question is how much carb. to to much. Everyone i talk to gives me conflicting statments. Would rather take the opinion and advise of guys that have done it.

Thanks scott
 

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how much carb. is too much
That's the $64,000 question. Everyone has a differing opinion on this, but IMO, a good 600 CFM Vacuum Secondary carb is a good choice for applications from "stock" to 300HP. It may not be the "perfect" carb, but it's usually a good/safe starting point.

Dave
 

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I am with you guys. I have edelbrock's 600CFM and it is reliable and works well for a small block. My dad had Holley dp's small and big on his and says he likes my 600 ALOT!!!
 

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Oh by the way 65 fast...what is done to your heads??? I want to run the cam you have but want input on it. Do you have a noticeable idle and are you running a stall with it??? Sorry to get off topic. PM if you want.
 

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I believe the HiPo 289 came with a 480cfm four barrel.
 

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500 cfm for better throttle response, gas mileage and drivability Gary
 

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Hi Scott,
This is the age old question and one nearly every backyard mechanic gets wrong.Most of course go with too big a carburettor.
Here's a good link that will calculate your needs.
What needs to be considered is that the bigger the venturi size the slower the air speed. There gets a point where you will lose low speed power and torque once the size gets too big.Also a vacuum secondary is the best option for the street. Double pumpers are useful for cars with low gears + bigger rev high stall converters.Hope this helps.
Ron

http://www.buicks.net/shop/reference/carb_cfm.htm
 

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Gary6768 said:
500 cfm for better throttle response, gas mileage and drivability Gary
I'm with Gary.

I had a 500 cfm Edelbrock on the 289 HiPo in my 67 GT350. Pulled hard to 5500 rpm, idled better and had more low end power than the 715 cfm Holley that was on it.
 

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After careful thoughtr, and much advice from here, i went with an autolite 4100[480 cfm, 1.08]on my stock 289, and am glad I did. It is original equipment[important to me], and also for the reasons listed above[response, mileage], not to mention they are becoming harder to find. I got a real nice one off ebay for a good price....
 

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You can also go with a nice cam and change the rear gears and still have a little carb. left over. Hope that carb works for you! I have a spare 480 4100 in the garage for when my Edelbrock 600 finally kicks. Now that there are good adapters it should bolt right on. I never could get to seal on the RPM manifold when I first did the build so I went with the Edel. I like them both.
 

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I have a done up 289 in my 66 and in my 67. The 66 has a 600 on it and the 67 has a 500 on it. The 66 is faster but the 67 with 500 is better to drive for the idle and better low end power but as others have stated it runs out at higher speeds. If your engine is only stock I am sure you would enjoy the 500 better. Also you should get better fuel millage as well.
Al
 

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Depends on what your plans are for the future. Depends on if you have a single or dual plane intake. Etc.
 

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2 rules of thumb. you can double the CI to come up with the carb CFM. So 289s usually do great running up to 600 cfm carbs. Stiffer cams will take lots more like the hipo runs a 715 (and mine in my shelby runs much better than the edelbrock 500 I had on it for a short time)...Secondly, with an auto trans car, do not go dual plane intake, stick to single plane. Hope this helps
Tony
 

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Secondly, with an auto trans car, do not go dual plane intake, stick to single plane. Hope this helps
From my experience the opposite is true...
Dual plane for slush box and single plane for manual tranny. My $.02
 
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