fuel mixture

[baconbiscut]

I have 1955 5.5hp CD-12 outboard and I use a 16:1 oil and gas mixture and it runs a little rich. and i also heard 24:1 works but i was lokking around at another forumand somebody said that he uses a 50:1 oil mixture in his outboard and his outboard is the smae hp and waqs built in the fiftys like mine and i was wondering if it would be alright to run 50:1 in my engine thanks just wanted to be on the safe side before doing such a thing

 

[jimmbo]

Re: fuel mixture

50:1 is too lean for your motor. In 1954 the spec was 16:1. In 55 the larger(25hp) used 24:1 but the smaller engine might still have been 16:1 The newer(post 1963) could use 50:1 mainly due to antifriction bearings in the connecting rods and wrist pins. Older motor used friction(bushing) bearings and needed a lot more oil to maintain a cushion of oil inside the bearing. Too little oil and the oil cushion is broken and metal to metal contact occurs damaging the bearing. There is no tag or decal on the engne specifying what the mix is? Some people will say with newer oils you can use less... Not so when the bearing needs the oils for cushioning. Its quantity not just quality. Anti friction bearings can and do get by with far less, sometimes less than 200:1.

 

[tashasdaddy]

Re: fuel mixture

my manual says before 1964 24/1 after 1984 50/1. you might be able to get to 32/1 with tcw 3, but i'm not going to recommend it.

 

[JB]

Re: fuel mixture

What daddy said.

In 1964 OMC changed the recommendation on all pre-1964 OMC built engines to 24:1 and all 1964 and later engines to 50:1. TC-W rated oil is required.

So, you should be using 24:1 with TC-W3 oil.

That's a wonderful little engine you have there, baconbiscut. Treat her right and your children will be using her 30 years from now.

 

[baconbiscut]

Re: fuel mixture

thanks for all the help