Which Carburetor???

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wyoduster

wyoduster

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Its time to put my engine together.... I thought I might as well spend the money and buy a new carb. I'm looking at Edelbrocks cause they look pretty cool ,no other reason....I'm also mounting it to a Edelbrock Performer intake.
Ok here it is I'm building a 340 .040 over w/20-222-3 Comp cam(.462 lift),4 Speed tranny. I have an electric fuel pump. anything else?
So Which Carburetor and why? CFM?:read2:
 
I have tired a 600, 670, 725 and 750 on my 360. This engine is a stout street motor which is making approx 370 HP with the 600 cfm carb (don't have any numbers with the other carbs).

Anyway the 600 has awesome throttle response from idle to up to 4500 rpm but does not have the power above 4500 that the 725 or 750 have. The 725 was just a bad choice (BG Road Demon) and was horrable below 2000 rpm. The 750 was OK in the low rpm range but not nearly as good as the 600 and had a definatel advantage above 4500 rpm. The 670 Street Avenger is what is on the engine now. It is every bit as good as tthe 600 down low and by the butt dyno it gives up nothing to the 725 or 750 up top.

Plus the 670 is getting 5 mpg more than the 750 and it's the closest to a drop on and go carb I have tried.

I would recomend that you stay in the 650 to 700 range.
 
I'm running a 650 double pumper on a Torker right now. I'm switching to a Performer RPM and 650 AVS this spring. I was going to go with a 670 Street Avenger, but picked up the AVS from a local FABO member for a good price.

I'd go with either a 670 SA or 650 AVS for you car. It will work great with your current combo and leave a little room to grow if you decide to make improvements in the future.

Just dont overcarb it...ie 750 double pumper or something...
 
wyoduster said:
Its time to put my engine together.... I thought I might as well spend the money and buy a new carb. I'm looking at Edelbrocks cause they look pretty cool ,no other reason....I'm also mounting it to a Edelbrock Performer intake.
Ok here it is I'm building a 340 .040 over w/20-222-3 Comp cam(.462 lift),4 Speed tranny. I have an electric fuel pump. anything else?
So Which Carburetor and why? CFM?:read2:
Click to expand...

Edelbrock 670 Street Avenger
 
I don't know the mathimatical formula to come up with the correct cfm that isneeded so I can only trust the guys at the machine shop. my 383 with just over 425 hp will need 595 cfm,,based on his calculations,,,it does seem low to me????but good luck, its kinda tough to pick the right one.
 
There are lots of calculators out there that will tell you how much air is required to support a given displacement, rpm and volumetric efficiency. Here is one; http://www.csgnetwork.com/cfmcalc.html

An engine never uses as much are as people think and for a street car you want to pick a carb that will be correct for the rpm range the engine will operate in the majority of the time. People always tend to over carb their engines. If you car is primarly a street car something in the 650 to 700 range will be more than adequate.
 
I setup carbs on Chevy dirt cars alot and (I know its Chevy what am I thinking?) but anyways they gave the class an option to run 4 barrels or 2 barrels and the guys with the 2 barrels were waaaaaay faster so its just a matter of getting the cfm right.
 
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