Lead Additive?

[turtle1173]

I was told that older engines were originally made to run on Leaded fuel, therefore a lead additive is a good idea. Does anyone have any advice/ experience with this? Is Unleaded harder on the engine or anything?<br /><br />Thanks,<br /><br />Shane

 

[Case]

Re: Lead Additive?

Lead (specifically tetraethyl lead) as a fuel additive provides two fundamental benefits. It slows the burn rate of the fuel, causing combustion to be less hot. The second benefit is its complex chemical reactions that provide specific 4 cycle engine performance improvements that are not specifically heat related, but affect lubrication and gas transfer.<br /><br />Basic information - the lower the octane, the faster (and hotter) the fuel burns. Airplanes are air cooled, so they run 100 and 130 octane fuels for temperture control. <br /><br />If your asking should you run an additive, my recommendation would be no. Just run premium fuel and occasionally run the decarbonizer from Evenrude or Mercury (both get high marks on this board, and there are guys who routinely post that definitely know what they are talking about).<br /><br />I suspect that there will be others who disagree.<br /><br />Case<br /><br />Women love me, fish fear me!

 

[petryshyn]

Re: Lead Additive?

Although lead was added in to slow combustion, one major benefit was the residue it left on engine parts. The residue accumulates on the valve and valve seat and cushions the slamming that occurs. Take away the lead and hammer out the soft valve seats. Other additives are now used that supposedly do a similiar function, though not as good. In old engines, stellite valve seats are the answer.....In 2-strokes, nothing to worry about....

 

[clanton]

Re: Lead Additive?

If it is an OMC product I have a chart for retard timing specs, and recommended fuel octane.

 

[petryshyn]

Re: Lead Additive?

hey clanton, can you send me or post that chart?

 

[clanton]

Re: Lead Additive?

Give me a few days.

 

[turtle1173]

Re: Lead Additive?

I guess I should of mentioned that I have a 1975 55HP Chrysler.<br /><br /> So, Schematic, would you recommend using the lead additive?<br /><br />Shane

 

[Fouled Plug]

Re: Lead Additive?

Turtle, 87 octane unleaded and a quality 2 stroke oil will keep you running just fine. Your motor has no valves, so no lead necessary. Keep the fuel fresh and don't sweat it. Save the lead additive for the '55 DeSoto

 

[turtle1173]

Re: Lead Additive?

Thanks Fouled Plug (and everyone else). I'm just trying to cover all my bases <br /><br />Shane