On Sun, 25 Dec 2011 15:29:54 -0500, Tony Miklos
wrote:

On 12/25/2011 1:21 PM, wrote:
Lead has been removed from gasoline and the choke has been eliminated
by the use of EFI and electronic engine controls in general.. This
accounts for the vast majority of the improvement in engine
reliability and life.

I never knew lead was in any way harmful to engines? What negative
affects did it have?
Lead had a serious problem with deposit build-up un the engines, so
Phosphorous compounds needed to be added along with the lead. This
produced phosphoric and phosphouous acid which accumulated in the
crankcase, causing oil breakdown and bearing pitting, among other
problems - and was also emitted in the exhaust - which ate up exhaust
systems at a high rate.

Even with the phosphorous compounds, valve deposits built up, causing
sticking valves and valve burning - and the deposits in the combustion
chambers increased compression ratios and provided hot spots that
caused detonation damage to engines - and also reqired higher octane
fuel to operate properly.
All in all, the removal of lead from automotive fuel solved a LOT of
problems, beyond removing lead from the environment.