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Author Topic:   890cfm
leftturn29
Member
posted March 17, 2004 03:50 PM
don't know if this is the right thing to do, so I thought I would get some input from the experts here on the forum--I'm thinking of switching to a 890 cfm 2bbl on my 358. is anyone else running this setup and what are the pros and cons. any and all input appreciated.


Ego Racing
Member
posted March 17, 2004 04:14 PM
Where did you get a 890 cfm two bbl?


udecide66
Member
posted March 17, 2004 04:29 PM
We had a 850 CFM two barrel but it was a machined center with Holley bowls and metering block and you had to notch a single plane intake to fit the butterflies.


leftturn29
Member
posted March 17, 2004 09:11 PM
a former racer down here in Louisiana says he has a C&S 890 cfm 2bbl that he ran on a late model, but that has been some time ago. I thought someone might be running this same type of carb on a modified now and could give some updated info.


KPLugnut
Member
posted March 18, 2004 07:11 AM
FYI, The C&S "890" 2bbl doesn't actually flow 890cfm in reality. It's more like 720-740.....

But it is heavily modified, like others have said.

KP

zeroracing
Member
posted March 18, 2004 07:47 AM
When we were running on asphault we ran a Bow Laws 850 cfm 4 bbl that flowed over 1000 cfm but we also twisted the motor real hard. That was a 331ci chevy. My only fear of the big 2bbl is the impact comming onto the throttle. Make sure your pedal linkage is good and you have control of the linkage, I have seen some guys where the linkage is so short and fast that it would slam open suddenly with no control.


leftturn29
Member
posted March 18, 2004 07:50 PM
Njantz alot of the guys around here are running aerosol carbs that are flowing no telling what. I was just looking for something to compete with without spending the $$. I may just be looking in the wrong direction.


donjuan12
Member
posted March 18, 2004 08:45 PM
NJ, one point that needs to be considered is that 2bbl carbs are not rated at the same pressure drop on a flowbench as a 4bbl carb is.
2bbls are rated at 3" Hg, and 4bbls are rated at 1.5" Hg (or 40.8"water and 20.4" respectively).
This means that a 2bbl carb that "flows" 800cfm or more is NOT at all the same thing as a 4bbl carb that is advertised to flow over 800cfm.

Apples and oranges, man. A small block (i.e., 355, 358, 383, 406, etc) can easily make good HP with a "giant" 2bbl without it being too much carb. Bolting on a 4bbl carb larger than 750cfm, for example, would NOT necessarily be advantageous, especially on short tracks.

Hope that helps,
KP


Ego Racing
Member
posted March 19, 2004 02:22 PM
The two bbl we had was flowed on the bench as a 4bbl. That is why I stated that with ours we had to notch the sides of intake spacer for it to fit. The butterflies were over 2 inches in diameter and the center section was milled for am aluminum block.
The two bbl will hit the tires and come out of the corner harder than a 4bbl but at top end the 4bbl will make more power.


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