[David Jones]

I have a question about how an intake manifold distributes the fuel/air mixture. The carb mixes fuel and air as they pass through it and dumps it into the intake. How evenly is that fuel/air mixture divided? Take a factory iron intake with a divider wall and upper and lower "planes". The front barrels of the carb are maybe a bit toward the forward end of the intake. Does that make one of the front driver side cylinders (6? 8?, I don't have an intake here in front of me...) tend to run richer when running on the primary circuit? Or does the demand from the engine pretty much even it all out?

[J_JAMNIK]

I believe that it is pretty well evened out with the exception of the PCV port. The ports I have seen do divide between both manifold planes to help keep a balance, but logic would make it seem that the front cylinders could potentially run a little more lean due to the PCV valve. I don't think it is even enough to worry about though cosidering the ratio of fresh air with fuel to crankcase air. If you have headers you might be able to get a temp reading of each exhaust tube to see how much range you have in temp differences.

[David Jones]

I do have a infrared thermometer and have checked each header tube. All outside tubes are about the same with the middle cylinders on each side just slightly higher.

To answer my own question, I suppose the reason various cylinders don't tend to run lean/rich depending on it's location is that each cylinder PULLS what it needs to operate since the engine is basically a pump.

[Half-Inch Stud]

Factory Dual-Planes and Torker I: Distribution of Air&Fuel mixture during WOT.

Since Fuel is heavier than Air, the runners forward of the carb outlets need to have a higher velocity than them rearward runners, to avoid front-CYL lean-out upon hard acceleration caused by WOT. - a theory worth thinking upon, then using the manifold that yields best plug uniformity after WOT.
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Discussion: idle, pull-away & Part-throttle cruise have no concern at all with distribution because there is a dramatically dominant and persistent "partial vacuum" in the plenum & runners along with low chassis acceleration. Therefore those modes-of-operation have mixture balance dominated by Exhaust-reversion pressure during the Cam overlap event, also the carb's basic mixture setting (too lean or too rich, or nearly ideal). Therefore: all 8 Sparkplugs SHOULD ALWAYS BE UNIFORMLY CLEAN for these modes of running, to know you even have a baseline. Trouble-shoot mixture such balance by questioning the Exhaust system & Cam Overlap, oh and fill them Exhaust crossovers.
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WOT is the special case (mode-of-operation) to focus our attention in the selection of ANY manifold's ability to do equal-or-moreso than the factory casting. Performance differences and Plug uniformity will be the hobbiest indicator, while Exhaust gas thermal balance will be the professional indication. Example: Aircraft use EGT to allow the pilot to correct mixture for the various altitudes during every flight.

My efforts to run Dual Holley on the Wenzler, then assemble dual Q-JETs on the Offyl Low-rise was interesting and fun. Dual Holley on Wenzler had excellent sparkplug read while Offyl did not. Dual Q-JETs have superior pedal feel.

YET, I'm back to the single Q-JET (swap-in 1050 DOM at will) on the Edelbrok Spreadbore P4B as the "Baseline", that someday will get a 1/4mile run, and swap-on the Torker I, then Tomahawk. Economic limitations have delayed getting results. HIS