Carburetion 101:
There are basically 3 major methods to atomize fuel:
(1) Add heat
(2) Increase velocity of the fuel/air mixture
(3) Add additional fuel
Several have mentioned the necessity of adding heat to aftermarket setups. Others have mentioned the heat conductivity of aluminum. While the aluminum WILL conduct more heat from the cylinder head to the manifold, it will dissipate this heat much faster to the air, thus the aluminum manifold will run cooler, almost always requiring heat.
But the OP asked about spacers.
For a trailered race vehicle WITH a 235 that is modified for full-blown racing, the spacers will PROBABLY help at wide open throttle, as the spacers in effect increase the plenum volume of the intake manifold. This tends to raise the RPM of the horsepower peak.
For a street engine, the spacers will PROBABLY require ADDITIONAL heat to be supplied to the manifold; and will PROBABLY hurt low end torque and horsepower.
Please note the use of the "probablys". There is no exact answer to the question. The answer will depend on the actual circumstances.
As to the "ole carb debate" mentioned by the OP: one of the great things about our hobby is the freedom to make our own choices. Some make better choices than others. If we were all to drive the perfect car, we would all be driving white with blue interior 1962 Jaguar E-types, and I would be walking, because I can not/could not afford one
Jon
