oil mixture for trolling

[Fishstick1962]

Hello all:
My dad has an old 79 85hp Rude and does alot of trolling with it at idle speed.
He may never hit WOT in 3 or 4 fishing trips.
The problem he is having is that it loads up on oil and fouls the plugs. Is there a solution for this or does he have to just live with it? He mixes gas to oil 50:1, I was wondering if he could mix a "Trolling tank" with a little less oil and use a "Running tank" for higher speeds. Has anyone done this? And will it damage the engine? Any suggestions are greatly appreciated.
Thanks!

 

[JB]

Re: oil mixture for trolling

Well, in theory that would work, Fishstick.

The original VRO (Variable Ratio Oiling) system ran engines at about 150:1 at idle. That was not available in 1978, though, so It might be dangerous.

I would be more inclined to open the gap on his spark plugs to .035" or even .040". That should really reduce plug fouling.

 

[Rudy Brown]

Re: oil mixture for trolling

I've heard that the old VRO pumps would pump 150:1 at idle and 50:1 at WOT. Some here on these forums will tell you that 100:1 is fine for your motor all the time with certain oils. I'm not a expert, but the problem with two seperate mixes is if you forget to switch tanks and run full steam down the river on your lean trolling mix, your motor wont be long for this world. I change my plugs 2-3 times a year anyway, so I premix 50:1.
JB, your a fast typer.

 

[JB]

Re: oil mixture for trolling

It's my turn, Rudy. I usually finish last.

 

[Fishstick1962]

Re: oil mixture for trolling

Thanks for the input guys. I think I'll try opening the gap alittle first. .035 and then .040 and see how she does. Thanks again.

 

[Texasmark]

Re: oil mixture for trolling

Merc had some fishing motors built on about a 20 degree tilt....specifically remember a 9.8 in the '70-'80 timeframe. The idea was to tilt the cylinders up in the rear to prevent fuel/oil from puddling at the head which helped to foul the plugs. Apparently it worked as they sold that design for a long time.

So, you might tilt your engine up (to some reasonable height) while trolling to "keep the fuel/oil from puddling at the head" in addition to the gap or running a hotter plug, or I understand surface gaps were supposed to be foul resistant for long periods of trolling.

Is there any reason he can't troll and then on the way back to the dock do some WOT blowout?

Mark

 

[LubeDude]

Re: oil mixture for trolling

I was wondering if he could mix a "Trolling tank" with a little less oil and use a "Running tank" for higher speeds.

For your original question, NO, there is no reason he couldn`t do this. 100:1 would be a good thing for trolling with a conventional TC-W3 oil.

Now, for the Amsoil discusion to start which has been hashed to death over the years.

I had one of those old Evenrude 85's years ago and even though I used it on a Bass boat and ran the living H*ll out of it everywhere it went, [I was fishing several times a week back then], I ran it on the original 100:1 oil Amsoil made back then. I ran it for about three months with the 100:1 mix, then went to an 80:1 just because it was easier to mix 5 gallons with a bottle than 6. Now they make an outboard only oil called Saber. There is no doubt in my mind that your Dad would do really well with this oil in his application and wouldn't have to worry about the run home with the same mix he trolls with.

 

[Salmonseeker]

Re: oil mixture for trolling

I had a Yamaha 15HP that recommended 100:1. I mixed it a bit richer to be safe. Maybe 80 or 90:1. It ran for 15 years on that mix. Then some @#@Hole stole it. I did a lot of trolling and never had a problem. Ran wide open a lot too. I personally think a leaner mix would not be a problem.

If my motor was a pre-mix I think I would try the Amsoil Saber Lubedude suggested maybe mixed at about 90:1 if you troll a lot. Even if it were regular TCW3 oil I would mix it a bit leaner if you spend most of your time trolling. It never hurt my Yamaha.

 

[tashasdaddy]

Re: oil mixture for trolling

i agree with JB, on opening the gap. was recommended on a lot of the older engine that did a lot of trolling.

 

[Texasmark]

Re: oil mixture for trolling

Now you have me confused. I heard/read (maybe in my service manual) where the Merc VRO is variiable ratio to increase the oil % at idle and the lower speeds above 50:1. I guess there's a reason or they wouldn't have (spend the money on) it and it makes no sense to me to have it anyway as before VRO you just ran straight 50:1 premix.

So now I hear that it's ok to lean it out.

Personally I agree with leaning it out as it doesn't take a rocket scientist to see the oil cloud at the low speeds.

Would appreciate a little clarification as to what's going on.

Thanks,

Mark

 

[Texasmark]

Re: oil mixture for trolling

Woooooooooh Nellie Belle (Jeep that Roy Rodgers sidekick used to drive with a roll bar no less, back in the 60's.....forgot his name....but I bet he didn't have a seat belt and if so didn't wear it cause I've seen him bouncing up and down in the thing).

Back the truck up. I got my wires crossed.

Beins it's been raining here for 2 months (drought for the last 2 years but this year is definitely the reverse....El Nino???) and storms almost daily, with another due to hit any time (from the Gulf of Mexico to Oklahoma, totally vertical not the usual SW to NE) it's too wet to plow and too dangerous to venture out so I am dealing with cabin fever.

So I dig out the Service Manual today and go to VRO and I gotta red face over this but I was exactly backwards on the oil ratio. The ratio that Merc decided would work was 80:1 (thats 80 parts gas to 1 oil not the reverse) for low speeds and 50:1 for high speeds.

That means that the lower speeds are leaner and all this stuff makes sense now.

Sorry for the disillusionment on my part. Don't like that word? Try antidisestablishmentarianism in a spelling bee. Grin. Don't laugh. Spell check didn't whack it so I must have spelled it (actually both of em) correctly. LOL Whadda deal geez and the beer cooler isn't empty yet....but give it time.

Win some loose some. Lost this one.

Mark