Quote:
Originally Posted by toddtheodd
Unless it's a quadrajet, the primary bowls are the same size as the secondary bowls, so it WILL affect low end grunt from the red light. Quadrajets have small primaries, and huge secondarys, hence the term "spreadbore". The small primarys were great for cruising around town and provided torque. The huge secondarys were for when it really opened up.
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Thanks for the lesson but that should be common knowledge for anyone that's worked on a carb and has absolutely nothing to do with what we're discussing. I believe I also implied the benefit of a q-jet. Otherwise GM wouldn't have used them for so long on so many engines.
Low end torque is directly affected by manifold vacum. That's why the small primaries of a q-jet provide more low end torque than the larger primary square bores. It's also why a dual-plane split plenum manifold provides more low end torque than a tunnel ram. That should also be common knowledge.
What we're talking about is the cfm of carb at wot. wot= wide open throttle.
We're also talking about vacum secondaries vs. mechanical.
I didn't see him ask about the difference between a q-jet and a square bore. It's good that you went in this direction though. Might offer him more choices.
Bottom line is, he is better off with the 600cfm, electric choke, vacum secondary.