Gas/Oil ratio for a 1963 5.5Hp Evinrude

[Ownsbud56]

I was told the ratio on a 1964 5.5 Johnson that I own was 50:1. Is the same ratio used on the 1963 5.5 Evinrude or is it 24:1? Thank you for your help!<br /><br /> Ownsbud56

 

[Paul Moir]

Re: Gas/Oil ratio for a 1963 5.5Hp Evinrude

Yeah, there's no difference between Johnson's and Evinrudes around that vintage. Virtually no differences between about '55 and sometime in the 90s with the Ficht & 4 strokes.<br /><br />So '64 is the 50:1 year. That and all years after it are officially 50:1. All the years before it are 24:1 unless you're talking pre-war, and then it gets a little dicey. There may be an exception to this. Joe Reeves says he remembers a service bullitin saying some pre '64 outboards could go 50:1. OMC did test 50:1 for years before actually making the switch.<br /><br />Now, to blur the lines even more, it's true that there are no known differences in what are believed to be the oil sensitive areas between most '63 OMC outboards and most '64. I believe your 5.5hp had earned all the internal parts regarded as necessary for running 50:1 by '61. But it may be wise to go with 24:1 for a variety of reasons besides the fact that it's the manufacturer's recommendation. <br /><br />Other small OMC outboards never got the parts needed until the late '70s, and so we see a much higher failure rate on the post '64 models than the pre '64 ones. Look how many 24:1 3hp engines we see here from the fifties verses say a '67 3hp run with 50:1. The oil mix FAQ in the FAQ forum covers which engines and why.<br /><br />Sorry for such a long post, but I thought you would appreciate the background. Normally when people ask I tell them the manufacturer's recomended mix, and add a caveat in the case of the 3hp.<br /><br />Additional reading:<br /> http://forums.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=037482#000007 <br /> http://forums.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=019327 <br /> http://forums.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000007

 

[Ownsbud56]

Re: Gas/Oil ratio for a 1963 5.5Hp Evinrude

Thank you for the information and the threads to review! What I am concluding from everything is 24:1 on the 1963 5.5, and 24:1 is advisable on the 1964 5.5 just to be safe! Specs say 50:1 on the 1964 as stated earlier, but 24:1 might extend its life if it operates okay on that mix? I am the type that does not like to tear anything up that might cost me later! I enjoy getting use out of the old motors that others have dicarded or given up on! Ownsbud56

 

[Chinewalker]

Re: Gas/Oil ratio for a 1963 5.5Hp Evinrude

Hi Ownsbud56,<br /> The key is whether or not the motor has the bronze sleeve bearings in it. The 3s, 4, and 5.5s are mostly, if not all sleeve bearings (depending on year). They gradually fitted roller and needle bearings into them as time progressed (the 3hp evolved into the 4hp which got rollers on the top main in the late 1960s, and full needle and roller by the late 1970s; the 5.5 evolved into the 6hp which was mostly needles and rollers when it came into the line in 1965), but in the meantime the blanket recommendation didn't work so well on the small motors. I have LOTS of early 1970s 4hp motor blocks with holes in them, crankshafts with buggered journals, and rods in pieces due to (in large part) the 50:1 mix it was recommended they run on. <br /><br />Your '63 is all sleeve bearings, so run it rich! There's a reason why it's still in service after 40+ years!<br /><br />- Scott