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Old 05-04-2012, 03:47 PM   #1 (permalink)
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Carb Size

I have a couple buddies who disagree on carb size. I have a 650 Carter on a 440 engine. One says its fine one says too small. ANy comments?
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Old 05-04-2012, 03:51 PM   #2 (permalink)
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With a stock intake and stockish cam and such that's just about right. Might go to 600 cfm also.
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Old 05-04-2012, 04:11 PM   #3 (permalink)
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Other guy says I should go to an 850-seems maybe too much, right?
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Old 05-04-2012, 06:01 PM   #4 (permalink)
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I have a 750 on a 440 with a mild cam and have considered going to a 650. Unless you have something real radical, 850 is way too much carb.
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Old 05-04-2012, 06:25 PM   #5 (permalink)
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My buddies 440 hp Belvedere 284 .484" purple shaft 4.10 gear and 4 speed had 800cfm double pump and was perfect on the street. Wicked little car.
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Old 05-04-2012, 06:42 PM   #6 (permalink)
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Quote:
Originally Posted by peterparr View Post
I have a couple buddies who disagree on carb size. I have a 650 Carter on a 440 engine. One says its fine one says too small. ANy comments?

peterparr, tell us more about your combo, car weight?,cam?,tranny?,rear end gear ratio?,tire?,street or strip? it all depends on all those factors.

john
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Old 05-04-2012, 06:57 PM   #7 (permalink)
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Quote:
Originally Posted by John Van View Post
peterparr, tell us more about your combo, car weight?,cam?,tranny?,rear end gear ratio?,tire?,street or strip? it all depends on all those factors.

john
Indeed...a 600 would be fine on a grocery getter, where a built up high output engine would need more CFM. Keep in mind throttle bore size, a 750 holley style carb modified to flow more CFM would be a wise investment on the street vs. an 850 with larger bores. The smaller carb would deliver better street-abillity while flowing good at high RPM. A spreadbore style carb of 850 like a Thermoquad is a great performer on the street as well.
Only on a full out racer is a larger carb (900CFM or larger) needed.
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Old 05-04-2012, 07:16 PM   #8 (permalink)
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This month in "Mopar Muscle" magazine, there is an article regarding carb sizing for a mild 383 that they've been working on.
They used Holleys from 650-cfm to 1050-cfm and got the best results with an 850-cfm #4781 Non-HP with mechanical secondaries....
The article also stated that the "most dramatic" increase was when they went from a 650-cfm to a 750-cfm.

I was disappointed that they didn't do a base line test with a Carter AFB or AVS.
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Old 05-04-2012, 07:30 PM   #9 (permalink)
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peter -

Like the other guys are saying - depends on what's been done to the engine and the purpose of the car.

IIRC Holley recommends about a 650 for a stock/mild street 440 and 850 for a more aggressive race engine.

That being said, my 440 has a bit of work to it (rated a little over 500 HP) and really woke up on the track going from a 750 vac to an 850 DP. The 850 has been on the engine for about 30 years. These days, since I don't race anymore, probably should go smaller, but it still works - so I'll keep it for the time being.

Check Holley's website, I believe they have a cfm calculator.

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Old 05-04-2012, 08:02 PM   #10 (permalink)
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You can read the specs on my 440 in my signature. I had a 870 Steet Avenger on it and it was too much. I jumped back to a 770 and it was much better.
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Old 05-04-2012, 10:27 PM   #11 (permalink)
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Did a quicky check on Holley.com and not knowing max rpm range i used 6000 and went thru the steps to get an answer according to Holley. suggested size was 750-870 cfm. And that was with out checking the 'race' button, just the street button.

So that being said, a 650 MAYBE a bit on the small side...
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Old 05-05-2012, 02:10 PM   #12 (permalink)
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I had a 870 Steet Avenger on it and it was too much.

How so, just out of curiosity.
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Old 05-05-2012, 04:06 PM   #13 (permalink)
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How so, just out of curiosity.
It was too rich. If I had a 1" spacer or an air gap intake then maybe it would have worked. Try putting any kind of spacer or such on a 440 A body.
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Old 05-05-2012, 05:33 PM   #14 (permalink)
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Eric -

Just curious, did you try playing with the jets and were you running the correct size power valve based on vacuum? Mine was running rich as well, until I dropped to a 5.5 PV (manifold vac was about 11 in gear, and the original PV was a 6.5).

Sorry, don't recall what jet size we ended up with.

Yes, the 4-hole spacer did make a noticeable difference in low end torque.

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Old 05-05-2012, 05:33 PM
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