What size carb is most appropriate?

[dyeager535]

what size would a stock quadrajet be if it came on a 305?

All Q-jets are physically capable of flowing 750 or 795/800CFM as cast, but typically limited on the secondary side to less than that. Primaries are 250 or 300CC's. (thats where the CFM difference was)

The TRUCK 305 Q-jets I've inspected have been 800's. (both '83's that I looked at) 305 Monte Carlos, even the SS, had 750 CFM variants, while the 307 Olds of the same vintage was 800CFM. Why? Have to ask GM on that one.

 

[TRex]

so if it was an 86' it might be an 800 cfm?
do you tell by the parts #?

 

[dyeager535]

http://dyeager535.topcities.com/qjetidentify.html

that link should work.

 

[onetonbb74]

Were you using a Truck Avenger?

no, a model 4150 double pumper. T/A are vacuum.

 

[rustyear]

in my humble opinion, the q-jet will work the best for your application...do not go with a 500 cfm 2bbl carb. the reason? engines like high speed air going thru the carb barrels for the best throttle response, and the holley 500 cfm'er has huge barrels, which slows down the air...its like having half of a 1000 cfm 4bbl. a 500 to 650 cfm 4bbl holley will work good and give you good response, but they are second-rate compared to a q-jet when you get off the road...not to say they arent doable, but they flood ezier and just dont tolerate inclines and off-camber positions nearly as good...but when you really get down to it, big cfm numbers only matter when you're wide open and up in the rpm range. you are gonna want throttle response, and whether you are just poking around at low r's or blasting up the highway, a small holley 4bbl or a q-jet will kick A on your engine.