Bogging down?
My 2 cents: "Bogging" under heavy accelerator opening is attributed to several separate but related items (by my dated recollection).
The most common is a too large carb dropping the vacuum in the system too low to properly vaporize fuel. This caused fuel to actually condense in the intake manifold. This was originally perceived to be a "starvation" issue and here come the "double pumpers" at 850 cfm and up. Not really the solution: Better performace was gained with the vacuum acctuated secondary air/fuel circuits that would not allow secondary throttle valves to open until there was suffucient vacuum to properly manage the fuel/air mix. Sometimes a smaller carb wil actually help. Wild cams exacerbated the problem. Also some open plenum manifolds can be culprits, again due to sharp drops or inability to maintain proper vacuum.
The "double pumpers" actually exacerbated the problem as well: Too low a vacuum not providing the air flow to vaporize the fuel equals too much gas; not enough air. Dumping more raw fuel into an overly rich mixture does not sound like the solution.
That's why the much maligned Q-Jet is actually a VERY capable street carb. Also check out the newer Holley vacuum carbs ("borrowed" the Q-jet concept?)
Whew! Its been a long time since I visited this and this is only my RECOLLECTIONS from a mis-spent youth. This is just another road to explore if you have this bogging problem.
Also check out the "How to hot-road Chevy Big Blocks" (or some such title). Lots of information in that book related to the problem you describe. It convinced me to save several hundred $$ on a change that would have led me down a slippery slope to ever increasing changes to fix a problem I never really had.
My 2 cents: "Bogging" under heavy accelerator opening is attributed to several separate but related items (by my dated recollection).
The most common is a too large carb dropping the vacuum in the system too low to properly vaporize fuel. This caused fuel to actually condense in the intake manifold. This was originally perceived to be a "starvation" issue and here come the "double pumpers" at 850 cfm and up. Not really the solution: Better performace was gained with the vacuum acctuated secondary air/fuel circuits that would not allow secondary throttle valves to open until there was suffucient vacuum to properly manage the fuel/air mix. Sometimes a smaller carb wil actually help. Wild cams exacerbated the problem. Also some open plenum manifolds can be culprits, again due to sharp drops or inability to maintain proper vacuum.
The "double pumpers" actually exacerbated the problem as well: Too low a vacuum not providing the air flow to vaporize the fuel equals too much gas; not enough air. Dumping more raw fuel into an overly rich mixture does not sound like the solution.
That's why the much maligned Q-Jet is actually a VERY capable street carb. Also check out the newer Holley vacuum carbs ("borrowed" the Q-jet concept?)
Whew! Its been a long time since I visited this and this is only my RECOLLECTIONS from a mis-spent youth. This is just another road to explore if you have this bogging problem.
Also check out the "How to hot-road Chevy Big Blocks" (or some such title). Lots of information in that book related to the problem you describe. It convinced me to save several hundred $$ on a change that would have led me down a slippery slope to ever increasing changes to fix a problem I never really had.
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