Quadrajet on a Slant Six
While it might seem that a 750 CFM Rochester Quadrajet is way too much carburetor for a slant six, I would have to disagree. Since it has air-valve secondaries, the Quadrajet actually performs like a small 2bbl carburetor. The primaries on a Quadrajet are rated at 161 CFM @ 1.5 Hg. For comparison, the primary side of a Holley 0-8007 (390 CFM) is rated at 195 CFM and the slant six Carter BBD is rated at about 202 CFM @ 1.5 Hg (~285 CFM @ 3.0 Hg). This is only slightly bigger than the original BBS which is rated at about 141 CFM @ 1.5 Hg (~200 CFM @ 3.0 Hg).
http://cars.rasoenterprises.com/Carburetion.htm
The air valves are spring-loaded so that the secondaries stay shut at wide open throttle until manifold vacuum pulls them open. On a 225 CID engine, they will never open fully, although I can hear them starting to open when Im accelerating at highway speeds.
Besides the small primary barrels, the other reason I like the Quadrajet is its small central fuel bowl. I have my carburetor mounted sideways so as to have a symmetrical fuel distribution. Whether this is really of any practical benefit is still up for debate. I found that the AFBs much larger fuel bowls caused a lean-out when making hard left turns. The Quadrajet works perfectly in this orientation. I believe off-roaders like the Quadrajet for similar reasons.
http://cars.rasoenterprises.com/Carb-Quadrajet.htm
While it might seem that a 750 CFM Rochester Quadrajet is way too much carburetor for a slant six, I would have to disagree. Since it has air-valve secondaries, the Quadrajet actually performs like a small 2bbl carburetor. The primaries on a Quadrajet are rated at 161 CFM @ 1.5 Hg. For comparison, the primary side of a Holley 0-8007 (390 CFM) is rated at 195 CFM and the slant six Carter BBD is rated at about 202 CFM @ 1.5 Hg (~285 CFM @ 3.0 Hg). This is only slightly bigger than the original BBS which is rated at about 141 CFM @ 1.5 Hg (~200 CFM @ 3.0 Hg).
http://cars.rasoenterprises.com/Carburetion.htm
The air valves are spring-loaded so that the secondaries stay shut at wide open throttle until manifold vacuum pulls them open. On a 225 CID engine, they will never open fully, although I can hear them starting to open when Im accelerating at highway speeds.
Besides the small primary barrels, the other reason I like the Quadrajet is its small central fuel bowl. I have my carburetor mounted sideways so as to have a symmetrical fuel distribution. Whether this is really of any practical benefit is still up for debate. I found that the AFBs much larger fuel bowls caused a lean-out when making hard left turns. The Quadrajet works perfectly in this orientation. I believe off-roaders like the Quadrajet for similar reasons.
http://cars.rasoenterprises.com/Carb-Quadrajet.htm
