carb question on 454

[ricks71pu]

Say, any one using a 600 cfm carb on their 454 BB? if so, your opinion? Too little performence?

[Ole Greenie]

I'd just like to say a couple things. First I am running a BB LS6 which really like to be turned..as in RPM. I had a Holley 650 single pumper elec. choke. I swapped it out last month with an Edelbrock 750 1411 and it really woke the motor up.

Truth be told, it depends on the RPM you will be turning. On a 454, if you willbeturning the motor over 5000 rpm, you will need more than 700cfm. If it is used as a work motor, a 600 or 650 is better. For my high reving LS6 (that came stock from the factory on 1970 in the Chevelle SS with a 800cfm carb) I thought the 750 would be a good match. and it seems to be a pretty good improvement and better fuel mileage too.

[ricks71pu]

yes, it is my daily driver, to work and errands, etc. so, maybe a 600 would be fine.thank you.

[Sinister]

I think a 600 cfm carb will be too small on a big block. Get a vacuum secondary 750, the motor will only use the fuel it needs.

[dougo]

I had a 650 on my k2500 burb with a 454. It was too small. I put qjet on it.... solved my problems.
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[68Stepbed]

454ci X 5000rpm /3456= 656.829cfm

The 600 may be a tad small for that engine. You could definetly use it for street use. If you plan to install a cam or rev it past 5000rpm, you might want to consider at least a 650 or 750.

I recommend either a well-built Q-jet or a 670 Holley Steet Avenger carb.

[DANTIP]

Originally Posted by 68Stepbed

454ci X 5000rpm /3456= 656.829cfm

The 600 may be a tad small for that engine. You could definetly use it for street use. If you plan to install a cam or rev it past 5000rpm, you might want to consider at least a 650 or 750.

I recommend either a well-built Q-jet or a 670 Holley Steet Avenger carb.

I agree with the RPM shown in the formula assuming you have a hydraulic cam. Secondly, most "Carb-Experts" (I'm not one) use the formula above with a .8 or .85 multiplier to correct for volumetric efficiency. An oval-port 454 would probably be around.85. Example would be 454 x 5000/3456 x .85= 558 cfm.

I think the 600 cfm will work VERY well. MOST people over-size carbs on street engines and suffer the consequences. The other quality (and personally recommended) alternative is a Quadrajet. When properly set-up, it really cannot be over-sized.