Carb advise needed
Thread Starter
Melting Slicks
Joined: Feb 2007
Posts: 2,136
Likes: 62
From: West Kingston RI
Carb advise needed
I bought a Edelbrock carb at a swap meet, never been on a car. My mistake was I listened to the guy selling that told mee it was a 600 cfm. When I got home I checked the numbers to find that it was a 500, model 1404. I have a friend with a Edelbrock 750, model 1407, willing to swap for the 500. My concern is, would the 500 will be to small but the 750 be to large, cfm wise? I have a rebuilt 350 325 hp motor with edelbrock performer intake.
Any advise on which would be my best route or should I just lookm for a 600. Will eventually be doing a 383 just happen to have the 350 for another project I was going to do so I thought I would put it in the vette for now.
Any advise on which would be my best route or should I just lookm for a 600. Will eventually be doing a 383 just happen to have the 350 for another project I was going to do so I thought I would put it in the vette for now.
Last edited by 929nitro; Jul 29, 2009 at 02:21 PM.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
You are right that the 600 would be a good choice for your setup.
CARBS Tests TQ/HP
Look at the area under the curve for Edelbrock 600 & 750. 600 is better for your setup.
http://www.corvettefaq.com/c3/carbcomparo.htm
You should try the 1404 esp. if you have an auto.
750 for 383.
CARBS Tests TQ/HP
Look at the area under the curve for Edelbrock 600 & 750. 600 is better for your setup.
http://www.corvettefaq.com/c3/carbcomparo.htm
You should try the 1404 esp. if you have an auto.
750 for 383.
Thread Starter
Melting Slicks
Joined: Feb 2007
Posts: 2,136
Likes: 62
From: West Kingston RI
Thanks for the advice. I'm leaning towards doing the swap and just buying a 600 for this motor and keeping the 750 for the 383, since the 750 only has about 10k miles on it.
Team Owner
Joined: Jul 2008
Posts: 23,419
Likes: 22
From: In limbo
St. Jude Donor '13-'15, '17 thru '22
The "common wisdom" is that a bigger cfm carb will give you more high end Hp, while a smaller cfm carb will give you more torque at a lower rpm. Ganey's data, although it does support the idea, surprised me by how small the differences were. He only got 1 Hp difference between the 600 and the 750 Edelbrocks.
Thread Starter
Melting Slicks
Joined: Feb 2007
Posts: 2,136
Likes: 62
From: West Kingston RI
If I remember right I was told that a basic 350 engine draws in between 600 to 650 cfm. So anything above that is pretty much wasted. Which is why I was concerned about both carbs in my original post. Correct me if I am wrong. I can turn wrenches but not up on a lot of technical performance stuff as to what is best to use. Triing to learn.
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
The "common wisdom" is that a bigger cfm carb will give you more high end Hp, while a smaller cfm carb will give you more torque at a lower rpm. Ganey's data, although it does support the idea, surprised me by how small the differences were. He only got 1 Hp difference between the 600 and the 750 Edelbrocks.
cc
Team Owner
Joined: Jul 2008
Posts: 23,419
Likes: 22
From: In limbo
St. Jude Donor '13-'15, '17 thru '22
I was also thinking down the lines of engine size and rpm too. If I have a 350 cubic inch engine turning at, say, 5000 rpm, I am filling each cylinder with air/gas mixture 2500 times per minute, which works out to 2500x350/1728=506 cubic feet per minute so I think that means a 500 cfm carb won't get me past 5000 rpm no matter what other components are on the system. Of course, this assumes a vacuum of 0 at WOT, which is probably an OK assumption for a weekend hobbyist like me, but probably wouldn't get me very far in the world of carburetor design. Using PV=nRT, the volume and pressure are geometrically related so 3 inches of Hg at WOT would give me about a 10% increase in the volume in the manifold, so I might get it done, but I would be cutting it real close.
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