[Rubbond]

Dear Bellerophon,

Manifold, duct, tract, all the same idea I guess? One way or another, if you
have 6 cylinders and 3 carbs, you will have to split the flow somehow.
I don't think using the exhaust as a sort of afterburner however is a very
good idea. From a thermodynamic point of view it's best to burn all of the
fuel inside the cylinders.

As to the fuel pump diaphragm, neither the ethanol in a "modern fuel" as you
call it , nor all the other additives or the basic naphtha for that matter
should be eating away at it. NBR rubber was produced already before World
War II, and is pretty resistant to both gasoline and ethanol.
Or are you are refering to "sour gas", which can be formed in small amounts
in unleaded gasoline? The effect of these hydroperoxides however can be
compounded around. I hope you are not buying original 1950's stock
diaphragms?

If your fuel pump is also bolted straight onto the engine, which I suppose
it might be on a pre-war design, there are much better rubber types
available today. I have cut out diaphragms and gaskets in the past from a
piece of cured FKM sheeting and a pair of scissors. That will last forever.

A "modern fuel", or leaded fuel for that matter, certainly doesn't break
down into ethanol, although with time the most volatile fractions will
evaporate.
"Stale fuel" is just what's left after the lowest molecular weight fractions
have evaporated. This will result in delayed onset of ignition and slower
flame proagation.
It takes a very long time however for a can of petrol to burn like diesel
fuel. You can still blow your head off.
And anyway, it's too late now to put some aside thinking it will be
drinkable this Christmas.

This was all a bit tongue-in-cheek but largely based on sound facts (or was
my prof telling porkies?).

With best regards,
Rubbond.