Leaded fuel in 1977 4.5 Merc outboard.

paulgp6022

Petty Officer 1st Class
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Jul 27, 2002
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Hi, I have the original metal gas can that is in good shape (no rust inside). On the top it says to use either leaded, low lead, or unleaded gasoline. Seeing that 1977 was on the cusp of phasing out leaded gasolines,and replacing them with unleaded fuels, does this mean that my motor can run on either? What would you guys recommend? I think 87 octane would be fine to use, but I am also thing about using 93 octane. Any help would be great! Thanks.
 

S.T. Marine

Petty Officer 1st Class
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Aug 13, 2002
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Re: Leaded fuel in 1977 4.5 Merc outboard.

Use 87 93 will do nothing for you
 

paulgp6022

Petty Officer 1st Class
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Jul 27, 2002
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288
Re: Leaded fuel in 1977 4.5 Merc outboard.

Thanks, would you happen to know the oil ratio for this engine? It is a single cylinder 1977 4.5hp Mercury. Thanks for any help!
 

S.T. Marine

Petty Officer 1st Class
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Aug 13, 2002
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Re: Leaded fuel in 1977 4.5 Merc outboard.

50:1 or 2.5 ounces to a gallon. Good luck
 

sloopy

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Jul 12, 2002
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Re: Leaded fuel in 1977 4.5 Merc outboard.

Can you still buy leaded gasoline??? heck I need some 80 octane leaded for some of my older motors :)
 

sony2001

Chief Petty Officer
Joined
Mar 17, 2001
Messages
607
Re: Leaded fuel in 1977 4.5 Merc outboard.

Mercury advised changing prop size to maintain full rpm and nothing else when the industry went to unleaded. But I don't think it applies to you. :cool:
 

JB

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Mar 25, 2001
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45,907
Re: Leaded fuel in 1977 4.5 Merc outboard.

Sloopy.<br /><br />No 2 stroke, ever, needed leaded fuel. Danged few will accept 80 octane fuel.<br /><br />Even in the old days, before your Dad was born, makers recommended unleaded (white) gas if you could get it. I recall at least one lil' outboard that stated in the manual not to use leaded gas, unleaded or benzene only.<br /><br />Good luck. :)
 

horndog

Petty Officer 1st Class
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Aug 6, 2002
Messages
279
Re: Leaded fuel in 1977 4.5 Merc outboard.

you can buy lead additive, hard to find, of all places I found that wal-mart sold it in the automotive section, it was like half gallon of the stuff
 
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