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Old 10-15-2007, 04:20 PM   #1
rogergodding
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Best size for carb?

I've got a mild performance 350(325hp) and need a new carb. Any suggestions for cfm? Currently it has a 600cfm Holley.
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Old 10-15-2007, 05:05 PM   #2
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Re: Best size for carb?

have the holley rebuilt its a good carb perfect size
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Old 10-15-2007, 05:16 PM   #3
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Re: Best size for carb?

had a couple guys that don't build cars or anything tell me that I should use a 750 dp I was thinking about rebuilding the 600, just got some junk in it from the old gas tank......
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Old 10-15-2007, 08:21 PM   #4
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Re: Best size for carb?

Quote:
Originally Posted by rogergodding View Post
had a couple guys that don't build cars or anything tell me that I should use a 750 dp I was thinking about rebuilding the 600, just got some junk in it from the old gas tank......

You might want to think about using 2 fuel filters, one before the fuel pump and the second before the carb. Try to use something other then $12.00 clear one with a cruddy paper element.

Here is a simple formula for figuring CFM

Rpm x displacement divided by 3,456
6000 x 350/3,456 = 607.64 your 600cfm Holley carb is spot on.
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Last edited by KFreddy; 10-15-2007 at 08:28 PM.
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Old 10-15-2007, 08:54 PM   #5
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Re: Best size for carb?

So in your opinion, should i have a 650 dp or 700 for a mild 383 stroker. Using both formulas i came up with just a little over 650? Thanks for the help.
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Old 10-15-2007, 09:20 PM   #6
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Re: Best size for carb?

Unless it's High RPM and big CUBES.......I would NEVER put anything on my truck but a Q-JET!!!!! Its 750 only when needed......It was used by the factory for EVERYTHING from a 305 to a 454. When 4-wheeling, it is only beaten by fuel injection! AND...if you're not into the secondaries...fuel economy is AWESOME.

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Old 10-15-2007, 05:33 PM   #7
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Re: Best size for carb?

Stay with the 600. If you have a radical cam and bore and stroke...then you need a bigger carb. Mild to stock...no more than a 650.
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Old 10-15-2007, 05:53 PM   #8
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Re: Best size for carb?

My vote is for the same carb that I have....an Edelbrock Q-Jet @750CFM. I've had mine on my truck for five years and haven't touched one time. Divorced choke has started it every time. No bog. No flooding. No trouble.
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Old 10-15-2007, 06:00 PM   #9
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Re: Best size for carb?

Quote:
Originally Posted by caminokid View Post
If you have a radical cam and bore and stroke...then you need a bigger carb. Mild to stock...no more than a 650.
I agree, I have a demon 750 dp on a 383 stroker with like 525 lift and 225 duration...

have a 750 on a smaller stroke/bore, you may as well take the ignition switch out, 'cause you would be able to kill it with your foot.
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Old 10-15-2007, 05:56 PM   #10
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Re: Best size for carb?

cool, never rebuilt one... guess I'll go pull it off and get started....
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Old 10-15-2007, 05:58 PM   #11
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Re: Best size for carb?

I assume it's junk from the gas tank.... it started running rough and backfiring.... has not been driven in close to a year, I run the engine every day or two....
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Old 10-15-2007, 07:27 PM   #12
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Re: Best size for carb?

I think the 600-650 is about right.You can use a bigger carb but the vacuum signal will be better with the smaller carb.You will probably benefit some in fuel milage from the smaller carb.
Now if you were drag racing or running flat out a lot you could benefit from a larger carb.Since most street cruising is done at part throttle the smaller carb should help keep the air velocity up and give you better PT response.
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Old 10-15-2007, 07:34 PM   #13
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Re: Best size for carb?

Based on all of these questions recently I decided to write a FAQ

http://67-72chevytrucks.com/vboard/s...d.php?t=262656
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Old 10-15-2007, 09:24 PM   #14
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Re: Best size for carb?

my vote for an Edelbrock 600cfm. for a stock 350 with standard internals, 600 will work without a doubt....

my .02
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Old 10-16-2007, 02:26 AM   #15
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Re: Best size for carb?

This is what you need Performer RPM Intake, Edelbrock 600cfm Electric choke
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