Evinrude fuel/oil ratio

[iggyw1]

Hi guys, I have an Evinrude, 1962 40 H.P motor. Model # is: 35933L. In my repair manual, (Seloc) it tells me to use a 24:1 fuel/oil ratiofor this model, yet on a different page, it says to use a 50:1 ratio but there is no model number listed, just the horse power (40) and year (1962) are listed with this recommendation. I ran for the past two years with 25:1. (I bought the motor that year). Motor ran real good, but had lots oil or gas on the water while I was anchored up fishing. Could not tell if it was oil or gas but it was a rainbow of colors on the water. Last year I switched late in the season to 50:1 at my mechanic's recommendation. (about twelve gallons of gas) Motor ran good and no oil on water and better on gas, yet I am reading that I should be using the 25:1 ratio. Any thoughts on this? Mechanic says the oils are made a lot better now-a-days and I will not ruin the motor if I use the 50:1 ratio. Should I trust this advice??? Manual states 24:1 AND 50:1, depending on where I look in the book.

 

[boobie]

Re: Evinrude fuel/oil ratio

As long as the motor has a full compliment of needle bearings on the connecting rod you can use 50:1. Another reason Seloc manuals Suck !!

 

[racerone]

Re: Evinrude fuel/oil ratio

In 1964 they magically switched to a 50:1 recommendation.-Was this due to market pressure or better oil ?-----Folks will argue this all day long until the beer runs out.------So take some time to compare parts / crankshaft / bearings / pistons between some 62 motors and 64 motors.----One thing for sure is that motors running on 24:1 will outlast the owner in most cases.

 

[oldboat1]

Re: Evinrude fuel/oil ratio

As indicated in your other post, if it were mine, I would go back to the 24:1 mix with good oil, the right plugs (J4C), and a new thermostat. Adjust the carb and make sure the choke is not sticking. The motor may be running rich for reasons unrelated to the oil mix ratio.

 

[jimmbo]

Re: Evinrude fuel/oil ratio

What Boobie said...

That engine is a fully anti friction bearing motor. it will have no problems nor will it be at any risk if it is run on a 50:1 mix. If the engine had friction bearings(bushing) on the connecting rods or crankshaft then even 24:1 would not be enough oil.

 

[oldboat1]

Re: Evinrude fuel/oil ratio

same case (50:1) can really be made for the Big Twins and Larks back to at least '57, but I figure why not just run with the specs.? The motor runs well at the 24:1 ratio if properly tuned -- think the poster's complaint is that he was seeing some sheen on the lake, and finds the 50:1 mix burns cleaner for him. If the motor is running cold, and/or with the wrong plugs, there might have been combustion problems. If the motor has an automatic choke, a sticky t.stat could adversely affect choke performance too, with resulting less-than-perfect combustion.

 

[jimmbo]

Re: Evinrude fuel/oil ratio

Back in the mid 60s OMC issued a service bulletin( I do have a copy of it some where) stating those engines could use 50:1.

 

[oldboat1]

Re: Evinrude fuel/oil ratio

yup. part of the magical switch referred to above, pretty sure.

 

[jimmbo]

Re: Evinrude fuel/oil ratio

In 1964 they magically switched to a 50:1 recommendation.-Was this due to market pressure or better oil ?-----Folks will argue this all day long until the beer runs out.------So take some time to compare parts / crankshaft / bearings / pistons between some 62 motors and 64 motors.----One thing for sure is that motors running on 24:1 will outlast the owner in most cases.

After OMC switched to 50:1, there was a very large drop in the number of warranty claims involving piston failures due to pre ignition.

 

[HighTrim]

Re: Evinrude fuel/oil ratio

While I agree that running that particular model at 50:1 will do no harm due to its bearing assemblies, I also agree that the motor should also be first gone through to ensure that it is simply not running rich for whatever reason.

A neighbour on my lake had an early 60s 40hp and was whining about a large sheen. I went over and his low speed packing nut had loosened, and the needle had spun itself out from the initial setting.

Sometimes it is a simple thing.

Additionally, I do not run my Big Twins on 50:1. These powerheads are no longer being made right. I want my grandkids grandkids to be able to enjoy them. You will never, ever convince me that switching to 50:1 is better in any way whatsoever, other than a couple less bucks a tank in oil, which Im not really worried about. A properly tuned motor, that is taken care of and annually decarbed, will not have piston failure due to preignition. If it is properly tuned, with strong spark, not worried about that.

Now does every proper motor owner follow proper maintainance, and tuning procedures? heck no, a lot of lazy people, and as long as the motor is running they are happy. That is a problem OMC corporation had to worry about.

 

[iggyw1]

Re: Evinrude fuel/oil ratio

I have the correct plugs in the motor, and I did change them every year for the past three years that I owned the motor. ( they are not that expensive for two plugs). It has a new thermostat in it, and I did replace the slow speed needle valve in the carb. I also use sea foam with every third tank full of gas and it really cleans things out and helps the motor run fantastic if you ask me! The motor just may need some fine 'tweaking' to get the rainbow around me to not be there when I turn the motor off and anchor up to fish if I were to continue to use the 24:1 ratio. . And at the same time guys, it did improve my gas usage when I cut down the oil to a 50:1 on the oil gas ratio. I am using about 1/3 less gas to be exact. Either way, with the 24:1 or the 50:1 the motor runs great, just don't like the gas/oil on the water. I tried to run it without the thermostat in at all, and that was a no-no!! Had 'gobs' of oil not burned and floating on the water & kinda gray in color when I tried it. That's when I put the new thermostat in.

 

[oldboat1]

Re: Evinrude fuel/oil ratio

sounds like you are on top of it, iggy. (always an interesting discussion over oil mixes, kinds of oil, all of that.) Got a good motor there, and used right -- good boating!

 

[HighTrim]

Re: Evinrude fuel/oil ratio

Yeah, leave that t stat in!

Something you can do, if interested in keeping excess oil out of the lake, is to rig up an excess fuel/oil catch system at the crankcase bleeder valve.

At the base of the powerhead, there is a plate, part number 302033 if you want to look it up. Behind that is a double reed bleeder check valve system, 1 for each crankcase, which dumps excess fuel/oil mix from the crankcase into the exhaust, and off into the lake, during the pistons downward stroke. This especially builds during low speed operation. Now, there is a way to tap a barb on here, and recycle this normally dumped oil. If you want the details on this let me know and Ill get into more details. I have done it, it is amazing how much oil/fuel you can save that would normally be tossed into the lake.

Removing this plate, and testing the operation of the reeds, and blowing air into the passage to ensure it is clear should be a standard maintainance item, but is either not known or often overlooked. It can prevent fouled plugs, and over rich conditions if the system is clogged.

That sheen you see is from operating at slow speed, and its the result of crankcase bleeding. It is the heavy ends of the fuel vapour which settle out during slow speed operation since velocity through the crankcase is not sufficient to hold them in suspension, and they settle in this pocket.

 

[Vintin]

Re: Evinrude fuel/oil ratio

HighTrim,
I'd love to hear more about this recapture system. I'm running a 1957 35hp Johnson. I've heard of this system before and would like to read about it again. thanks.


I've got what looks like two weeping spots on the port side of the powerhead and one looks like it weeps more than the other, maybe twice as much. I bet I need to look into it.

 

[HighTrim]

Re: Evinrude fuel/oil ratio

It is pretty simple to do.

Simply remove the cover 302033, part number 47 in the power head group in the parts manual. Drill/tap it to accept fuel barb, and install.

Now you need to plug the original hole leading to the exhaust with an appropriate size drill bit or round stock, leave it loose, then totally seal with epoxy.

Ensure the valves are functioning while in there and will come off their seat and are not plugged.

Now re install cover. Run a fuel line to a bottle or whatever catch system you come up with. You will notice much more accumulation at idle as I said than if you run around at WOT.

Now a good trick here is to now convert the motor to run on a fuel pump. However, KEEP the pressure tank line and fitting. Use the old air line as your oil return line back to the tank. Put a barb on the cap of the fuel tank, and you are complete. Your hidden oil recovery system looks like a stock pressure tank setup

 

[iggyw1]

Re: Evinrude fuel/oil ratio

Yeah, leave that t stat in!

Something you can do, if interested in keeping excess oil out of the lake, is to rig up an excess fuel/oil catch system at the crankcase bleeder valve.

At the base of the powerhead, there is a plate, part number 302033 if you want to look it up. Behind that is a double reed bleeder check valve system, 1 for each crankcase, which dumps excess fuel/oil mix from the crankcase into the exhaust, and off into the lake, during the pistons downward stroke. This especially builds during low speed operation. Now, there is a way to tap a barb on here, and recycle this normally dumped oil. If you want the details on this let me know and Ill get into more details. I have done it, it is amazing how much oil/fuel you can save that would normally be tossed into the lake.

Removing this plate, and testing the operation of the reeds, and blowing air into the passage to ensure it is clear should be a standard maintainance item, but is either not known or often overlooked. It can prevent fouled plugs, and over rich conditions if the system is clogged.

That sheen you see is from operating at slow speed, and its the result of crankcase bleeding. It is the heavy ends of the fuel vapour which settle out during slow speed operation since velocity through the crankcase is not sufficient to hold them in suspension, and they settle in this pocket.

I am very interested in this. I will check it out as soon as I get my boat out of winter storage and in my garage. It may be awhile here in Michigan before this happens this season. We still have about 20 inches of ice on our lakes, and it is still freezing here every night as soon as the sun goes down. Seems like winter here will not end!!

 

[HighTrim]

Re: Evinrude fuel/oil ratio

I feel ya. I am just north of you in Ontario. Worst winter I can remember in quite a while!

Im hoping my poor Walleye did not freeze to death in my lake this winter!

 

[Vintin]

Re: Evinrude fuel/oil ratio

Thanks so much HighTrim.

 

[boobie]

Re: Evinrude fuel/oil ratio

I feel for you guys. It was 85* down here in FL today and supposed to be the same way all next week. That's the reason I moved here from northern WI 25 years ago.

 

[iggyw1]

Re: Evinrude fuel/oil ratio

Hi boobie,

We were in Nuevo Villarta Mexico for the three weeks and it was anywhere from 82 to 89 degrees and not a cloud it the sky for the entire three weeks! Then we had to come back to Michigan and it snowed 5" the day we got home!!! I would love to move south but the wife won't hear of it because she would never leave our 5 grand kids! Ice on the lake here is down to 15" and starting to break up in the lake and go into the river. I live by Lake St Clair and I am waiting for the ice to clear out of the Detroit River to go and get those monster walleyes up to 14 pounds. Not good to eat but excellent mounts for the wall.