If the '56 type intake manifold has a divided plenum under the carbs, and you're driving along with just the rear primaries open, the front intake plenum will be under a high
manifold vacuum condition because the front four cylinders are functioning as a vacuum pump driven by the rear cylinders. The gas mileage will be worse because the throttle needs to be open farther to drag the front half of the engine along. There will also be plenty of vacuum to suck oil past the rings and also suck gasoline through the idle circuits in the front carb, to mix with it.
The V/8-6-4 engines work because they have provisions for de-activating the valve lifters in those cylinders to elimination energy draining pumping loses (vacuum).
The second generation hemi (426) has a four-stage throttle linkage installed, it's fairly complicated, with links installed on both sides of the carbs. Next time you see a 60s Hemi musclecar at a car show, take a squint at the top of the engine and you'll see what I mean.
I
Mike
At 11:13 AM 11/24/2009, Eastern Sierra Adjustment Svc wrote:
> Is this such a bad thing, for the
engine, to have gas be delivered, initially, only to the rear
> cylinders? The front cylinders are still getting the oil supplied to them.
>
> The new Hardly Dangerous motor cycles have a provision where, at prolonged stoppages,
> the rear cylinder has its fuel supply interrupted, in order to avoid any overheating of the engine.
>
> And, we all know about the current V/8-6-4 provisions on modern cars.
>
> So, outside of a racing venue (yeah, like any of us do that, anymore), what difference/effect would
> there be, using the 56 aluminum intake, with a progressive linkage employed, with 57+ m.y. carbs,
> wherein the front carb begins to supply gas when the rear carb's primaries open to about 30%?
>
> BTW, I've got an old (what other kinds are there?) issue of Hot Rod, where it shows you how to
> adjust your 57+ linages so that all 8 barrels operate in the
manner of the 55-56 versions.
>
>
> Neil Vedder
>
>
>
>
Archangel1390@xxxxxxx wrote:
>> *Nick,*
>> ** * If the dual quad manifold is the 1956 Fury aluminum manifold without the automatic chock heat tube, _then you must run straight linkage to make the engine gets gas to the front and back cylinders._ If the manifold is 1957 or 1958 dual quad manifold made of cast iron and has the chock heat tube then you can run progressive linkage or straight linkage.*
>> * The front part of the 56 Fury aluminum manifold and the back part of the manifold has a wall inside it that separates the rear carburetor from feeding the front 4 cylinders.*
>> * The most important thing you can do is make sure
you are _getting full throttle_ when the pedal is to the metal. DO NOT UNDERESTIMATE THE RETURN SPRINGS. THEY MUST BE RIGHT ALSO FOR FULL THROTTLE.*
>> ** * Ron Swartley*
>>
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