1959 Plymouth Atomic Punk Bubbletop - photo

[Frank S]

looks to have 8 2 bbl carbs that would be a bugger to jet properly so the engine could idle in order to make it street reliable. they would absolutely have to be flow bench match tuned I like that custom fabricated 10 or 12 inch rise deep plenum tube manifold sitting on top of the Hemi though

[Wildwilly]

looks to have 8 2 bbl carbs that would be a bugger to jet properly so the engine could idle in order to make it street reliable. they would absolutely have to be flow bench match tuned I like that custom fabricated 10 or 12 inch rise deep plenum tube manifold sitting on top of the Hemi though

I would disagree with you Ken. Those carbs are in a common plenum so it is only the total outcome of the plenum that must be in tune with the engine. Depending on how the plenum is designed with baffles, each carb does not have to be in the same AFR as another.

[Frank S]

I would disagree with you Ken. Those carbs are in a common plenum so it is only the total outcome of the plenum that must be in tune with the engine. Depending on how the plenum is designed with baffles, each carb does not have to be in the same AFR as another.

While admittedly they would not be as critical as a set up on 8 separate down tubes without a conjoined single or duel level plenum chamber, but just like a 6 pack set up on a Plymouth road runner let 1 or more of those vacuum spray boxes have differing air fuel ratio settings or a throttle plate open more or less than the others and the performance of the engine is going down the tubes either rough or surging idle the torque curve gets thrown off and HP rise at high RPMs floats
With 8 carbs one would be positioned over each tube leading down from the plenum even thought eh chamber would be common for all of them the one closest to any given tube is going to spray down that tube more than it will mix with the others in the plenum. The 1 advantage of the large plenum chamber is there would be a balanced vacuum through out though the atomized fuel would largely be gravity driven when a given intake valve was open. the rapid opening and closing of the intake valves creates a negative and zero pressure pulsation
A v8 engine with a 3 duce set up will actually run better on 2 carbs than it will if 1 of the 3 is over or under fueling or has an early or late throttle response setting I would think this may even be compounded with 8 carbs.
Of course just like a duel quad or a 3 duce the 8 duce could take advantage of having progressive throttles and idle on 2 or 4 then run on 4 to 8 and power on the 8 secondary's