ethanol free gas

[NFATrustGuy]

FYI Leaded fuel will not gum up your valves. What it will do is plug up your catalytic converter because the lead will not burn out of it. It also causes lead fouling on the spark plugs.

I know more about aircraft engines than car engines. Mine in particular is a 200 cu.in., horizontally-opposed air-cooled version. Manufacturers of new cylinder assemblies for this engine have redesigned their valves and valve guides specifically to combat the problems presented by the excess lead in 100LL fuel. Here's an excerpt from the ECI Cylinder website:

"Valve guide sticking for these series of cylinders has become a chronic problem for the aging aircraft fleet. Lower compression engines such as these are plagued by a lead compound build-up in the valve guides and the 80/87 fuel these engines were designed to use is no longer universally available. The available fuel (100LL) has an excess of lead that does not adequately scavenge, and subsequently forms carbon/lead compound deposits in the valve guide.

To reduce the build-up of carbon and varnish due to the excess of lead, ECi now adds a Roto-Coil to the exhaust valve to allow positive rotation of the valve each time it is opened, which then presents fresh mating surfaces to the valve stem and guide. Fresh, clean mating surfaces help transfer heat to the cooling fins and reduce the likelihood of both guide wear and valve sticking."

That quote was pulled from this website:

http://www.eci.aero/pages/products_titan_0200.aspx

Admittedly, I have no idea if car engines are already designed to handle 100LL's 20-fold increase in lead content as compared to unleaded automotive fuel. They may be...

I **do** agree that the extra lead will also foul a catalytic converter and cause lead fouling of spark plugs. Admittedly, these are probably the primary concerns for cars running 100LL.