1958 Johnson, Fuel, 25 to 1 or 50 to 1

[donofish]

I am restoring Twin 58 Johnsons RDS20 35HP , the books say 25 to 1, and I have tested these in a barrell, quite smokey.
I went to an old boat show at Lake Arrowhead, CA a few weeks ago, and was surprised to find a guy with the exact same motors, on a glass boat. I started talking to him about the motors, and restoration. I asked him about 25 to 1 fuel, he said that he was told that if he used the modern oils he should run them at 50 to 1.
He started them up and they sounded pretty good.

what do you all think???

thanks Dono

 

[Doug N.]

Re: 1958 Johnson, Fuel, 25 to 1 or 50 to 1

There was a recent similar thread that said to run the richer mixture. It doesn't have to do so much with the oil as it has to do with the engine materials. I have an older Evinrude and I run 24:1 like the motor says. If it is tuned up it doesn't smoke or leave a big trail.
If I had a spare, I would try the lean mixture and run it to see if it makes a difference. Since I only have one motor, I'll let someone else doe the experiment.
Best of luck.

 

[Vic.S]

Re: 1958 Johnson, Fuel, 25 to 1 or 50 to 1

According to http://www.evinrude.com/en-US/Owners-Center/FAQ/OilAndFuel mostly 1958 and earlier models ran on a 20:1 mix !

However your RDS20 has all roller bearings so will happily run on 24:1 or 25:1 and would probably be OK with less oil 40:1 perhaps

Stick to the mixture in the book. A synthetic oil may smoke less and it'll smoke less once you get it out of the barrel and can run it properly

Adjust the mixture screws according to Joe Reeves' instructions on the Engine FAQs board http://forums.iboats.com/showthread.php?t=167352

24:1 is 2 pints in 6gallons

 

[lindy46]

Re: 1958 Johnson, Fuel, 25 to 1 or 50 to 1

I use 24:1 in my 1957 Lark. I wouldn't chance a leaner mixture. Use TCW-3 oil.