how big of carb i can go on a 5.3

[rafael martinez jr]

hi i just out in a 5.3 in my 80 malibu the cam ia a comp cam 604-610 lift 215-223 dur @ .050 a set of 862 heads i bought fully ported and bigger intake valves , victor jr intake ,full length headers and a turbo 400 with a trans brake 3,50 gear in a 9in also have a nos kit 150-250 shot looking to see how big of a carb i can run its my first ls motor also replaced rod bolts with arp,and good race pan new oil pump and timing chain its a truck motor any help thx

 

[bracketchev1221]

I wouldn’t go bigger than a 750.

 

[rafael martinez jr]

I wouldn’t go bigger than a 750.

k cool a double pumper its what was looking at from proform thx

 

[pontiacgp]

size of a carb is only based on the engine size and max operating rpm.

Example: Using a 355 CID engine x 5,500 max rpm = 1,952,500

Take 1,952,500 x .85 = 1,659,625

Then 1,659,625 ÷ 3456 = 480 CFM

 

[81Regal]

750 is way too much carb for basic 5.3, a 650 would be a better pick. There is some great videos online on how to pick and tune all types of carbs. Personally I would keep it fuel injected.

 

[pontiacgp]

I would not go bigger than a 600....we used a 500 2BBL holley on a 350 in our G body circle track cars and that never ran out of fuel with a 6300 rev limit chip

 

[383_GrandPrix]

How big of a carb CAN you put on it? Well Holley sells a 1475cfm dominator.

 

[L92 OLDS]

What made you choose a carburetor? It’s old technology and your 5.3 came with fuel injection.

 

[bracketchev1221]

Did any of you guys this is a mild race setup with a 250 hp nitrous kit?

 

[383_GrandPrix]

Judging by the parts you've listed I'm guessing that you're building a drag car, 7000rpm red line?



325ci × 7,000 = 2,275,000

2,275,000 × .95 = 2,161,250

2,161,250 ÷ 3456 = 625.36



I used .95 in my calculations as opposed to the .85 pontiacgp used because the LS platform will have a higher volumetric efficiency than an older SBC, as well as taking into consideration the parts you've listed. If you're not driving it on the street you'll be able to get away with using a carb that is a little on the bigger side because the engine will basically only be seeing wide open throttle and you're not looking for throttle response or drivability. With that being said too large of a carb can hurt your numbers, and you also have to remember that the odds of a carb running perfect out of the box are slim to nil so no matter what size you buy be ready to tune it or have it turned by someone else.