old motors vs unleaded gas

[tim hagewood]

I have a 1968 50hp mercury ob. I know in 1968 the gas contained lead in it with the unleaded gas do i need to add a lead additive? And what about adjusting the timing for the difference in octane?

 

[Chinewalker]

Re: old motors vs unleaded gas

Leaded gas has no bearing on 2-stroke outboards. Your motor will run fine on pump gas without any changes. HOWEVER, some fuels containing alcohol may have adverse effects on your fuel system. Jury is still out on how bad it is and what effects are long term...
- Scott

 

[jjacobs007]

Re: old motors vs unleaded gas

i got a 73 f100 with all alluminum runs on unleaded,just like your outboard.no lead doesnt matter.had a 1964 johnson ran awesome on unleaded for years.

 

[CharlieB]

Re: old motors vs unleaded gas

Sporty,

They engineers were playing that CYA game, by printing the manual 'requiring' leaded fuel they absolved any responsibility for engine failure by claiming the customer failed to run the required fuel.

As it turned out, there was NO performance difference, NOR any reliability issues between the two fuels.

Since then the introduction of alcohols into the mix they have had to make changes in the rubber and plastics to withstand the drying effects of the alcohol.

 

[j_martin]

Re: old motors vs unleaded gas

Gasoline back then was leaded, but also had a little higher octane and no alcohol. Both are significant.

I would run a 92 - 93 octane "off road" non-oxygenated (alcohol free) fuel if you can get it.

I run a lot of small motors, some 2 cycle and some 4 cycle. Since I quit using any fuel with alcohol in it in any of them, I have done a lot less fuel system maintainance.

hope it helps
John

 

[mjc3834merc]

Re: old motors vs unleaded gas

For a list of stations that sell non-oxygenated gas in Mn go here. I only use 91+ alcohol free gas in my outboards.
http://www.msra.com/NonOxygenatedFuel/NonOxyList05.04.09.pdf