[VAC] Re: Vintage haulers and unleaded fuel

["Carol and Oliver Filippi" <ofilippi@xxxxxxxxxxxxx>]

In my opinion this notion of tetraethyl lead needed for valve life longevity
is a lot of baloney.

First of all, the amount of tetraethyl lead anti knock compound that was
added to a gallon of gasoline was less than a teaspoon.

However, before we trash this antiknock compound, recognize that it is a
very inexpensive and effective way to increase the octane rating of gasoline
for use in Otto cycle (gas) engines.   It was responsible for the 145 plus
octane of aviation fuel, which permitted higher thermodynamic efficiency
(more powerful, and more fuel efficient) engines such as those used on the
B-29.  Lead antiknock compound played a major role in our winning (and
surviving) WW II.

In the Northeast during the 50's and 60's and 70's, the best automotive
gasoline was AMOCO  UNLEADED  Premium.  Both my father and I used it almost
exclusively in Cadillacs, Oldsmobiles, Chevy Corvette, Chrysler Hemi, etc.
and never had valve problems.  All of these engines used hydraulic valve
lifters.  Also, these engines were the modern overhead valve, high
compression design. [Which had higher combustion chamber temperatures than
their lower compression forerunners.]

The major cause of burned exhaust valves is a lean fuel mixture which
appeared on the scene en masse when the air pollution regulations of the
70's took effect.  That was when the auto industry switched to unleaded
regular (lower octane fuel). Actually, it was the old premium fuel minus the
tetraethyl lead, hence of lower octane.  The reason they went with lower
octane unleaded, was because this was the only fuel available in sufficient
quantity which would not foul some of the anti smog devices on the engine.
Most of the refineries did not have the "Ultraformer" which AMOCO used to
refine the higher octane unleaded fuel.

I believe that the correlation between the leaner  burning smog tuned
engines, and the requirement that they run on unleaded fuel is the reason
leaded fuel is credited with extended valve life.  I don't believe this is
really the case.

As Charles F. Kettering, the former chief engineer of General Motors once
said, (paraphrased), "The trouble with most people is not that they don't
know enough, but that they know too many things that are not true."

Incidentally, it was Kettering and his successor Ed Cole who developed the
modern high performance gasoline engine - overhead valve (they called it
valve in head in those days), high compression(7.25 to 1, as compared to 6.5
to 1 of that era), and short stroke.  This design  first appeared on the
1949 Cadillacs and Oldsmobiles in the fall of '48.  Cole is the person who
made the call to switch to lower octane unleaded fuel to meet the (then) new
emission regulations.

Oliver Filippi