Johnson 24:1 vs 50:1 Ratio

[IronWill]

Sorry if this has been discussed before.

I?m currently running a 64 model 40hp Johnson that calls for 50:1mix. I have a spare 63 model 40hp. I?d like to dig in and do a complete overhaul of the 63. I?d like to know what Johnson did to change the mix ratios between the model years. I?d like to stick with a 50:1 if possible.

Also, where is the best one stop shop to get a complete overhaul kit?

Thanks,
-Will

 

[Chris1956]

Re: Johnson 24:1 vs 50:1 Ratio

Will, the difference should be in the bearings. 50::1 mix motors are all roller, needle and ball bearings. 24::1 motors have bushings or sleeve bearings.

I would send a PM to Joe Reeves. He can probably tell you off the top of his head if you can go 50::1 with that motor.

 

[kbait]

Re: Johnson 24:1 vs 50:1 Ratio

You can get most parts needed right here on iboats parts w/good prices. You'll need to get an OMC/BRP carb kit if you want the float.. sierra kits sold here don't include float.
I found this:


posted 05-31-2009 06:21 PM ET (US) Profile for modenacart Send Email to modenacart This is from the Evinrude website.

"Q - What is the fuel/oil mix for my motor?

A - The following is generally true: 1958 and prior used 20:1, 1959 thru 1963 used 24:1, 1964 and newer use 50:1. High performance usage (racing) requires a ratio of 25:1. New engine break-in (not DI) requires 25:1."

The link to the information is


http://www.evinrude.com/en-US/About.Us/FAQ/Oil.Fuel.htm?popup=true#Q2.

 

[seahorse5]

Re: Johnson 24:1 vs 50:1 Ratio

Sorry if this has been discussed before.

I?m currently running a 64 model 40hp Johnson that calls for 50:1mix. I have a spare 63 model 40hp. I?d like to dig in and do a complete overhaul of the 63. I?d like to know what Johnson did to change the mix ratios between the model years. I?d like to stick with a 50:1 if possible.

Also, where is the best one stop shop to get a complete overhaul kit?

Thanks,
-Will

OMC did not do a thing to change the 1964 40hp from 24:1 to 50:1. As long as the motor has full roller or needle bearings, it can run 50:1, so no problem with the '63. OMC did come out with a service letter or bulletin confirming that fact.

Most of the smaller motors had brass bushings for main bearings or for rod bearings and those have to run 24:1. In later years they were changed to needle bearings to be able to run a 50:1 mix.

 

[F_R]

Re: Johnson 24:1 vs 50:1 Ratio

They were only approved for 50:1 if you used Johnson or Evinrude TCW oil. And that is what they changed. Today's TC-W3 is the third generation of the oil, much better yet.

I'm not going to tell you to use 50:1 in your '63 because if it tears up, you will blame it on the oil, no matter what the real cause, and say it was my fault for telling you to do it. But the '63 and '64 are the same inside. Draw your own conclusions.

 

[1946Zephyr]

Re: Johnson 24:1 vs 50:1 Ratio

Yes, in 1961 and later, all OMC's were needle bearing set ups, except for the Lightwin/JW models. 1960 and earlier, the 5.5's and 7.5's were the same set up as the 3's. These were the motors that needed the richer mix. What F_R says, is correct. You can actually get away with running 50:1 on the 63 model engine, because it's virtually identical to the 64. Internally, it is exactly the same.