What fuel-oil mix? 1961 75 hp V4

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n0ukf

Petty Officer 2nd Class
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Jun 24, 2003
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Dad just got a 19' Larson boat with a 1961 V4 75 hp Johnson (model V4A-13). What is the proper oil mixture for this, 24:1, 32:1, 50:1? If I don't see an answer to this before we take it out, I'll suggest he tries 32:1 as a middle ground when we fill these empty and near empty tanks. (Never go out with only one tank of gas.)
 
bubbakat

bubbakat

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Re: What fuel-oil mix? 1961 75 hp V4

My manuel says 50:1<br />
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seahorse5

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Re: What fuel-oil mix? 1961 75 hp V4

Originally it was 24:1, but in 1964 OMC changed it to 50:1.
 
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n0ukf

Petty Officer 2nd Class
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Jun 24, 2003
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Re: What fuel-oil mix? 1961 75 hp V4

I thought I was posting this in the J/E forum. :confused: <br /><br />seahorse, are you saying that in 1964 OMC changed the mix for the '61 model?
 
JB

JB

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Re: What fuel-oil mix? 1961 75 hp V4

OMC changed the mix in 1964 for engines built after 1964.<br /><br />Some earlier engines will survive a 50:1 mix, but I wont try it.<br /><br />From my manual, it is clear that the V4A uses ball and rollers on the crank and needles on the big end of the rods. It is not clear what is on the small ends of the rods, so I suspect that they are friction bearings that require the 24:1 mix.<br /><br />I would use 24:1.<br /><br />Good luck. :)
 
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