[Chevelle-List] Quadrajet Revisited

[Tom Tomlinson]

This goes back to a carburetor discussion about 3 weeks ago.   I've been considering rebuilding my 4160 Holley (600 cfm), going to an Edelbrock performer 600 cfm, or a Quadrajet for my '71 350 Malibu. In the Edelbrock selection guide, it suggests a 600 cfm performer or a 750 cfm Quadrajet for their performer intake manifold. I couldn't figure out why the large difference in cfm between the performer and the Quadrajet; 600 cfm is about right for my engine (and the manifold), and when I posted the question to the list, no one responded.   The answer is on this web site:   http://www.goattraks.com/tech/q-jet/q-jet-5.htm   Apparently, the Quadrajet comes in two versions, a 750 cfm and an 800 cfm. The air valves on the secondaries of the 750 were designed with stops to limit air flow according to the cfm required for the engine. So the original Quadrajet on my car had secondaries that were limited to a 70 degree opening (90 degrees being full open) to create the proper cfm rating for the 350 small block.   Didn't know if this was common knowledge, but I thought it was interesting.   Tom Tomlinson '71 Malibu 350