Breaking in a new engine

[Chuck Sturgis]

Hey guys...... I have another newbie question..... I have been running gas boats for awhile but this is my first go with a 1/8 scale nitro boat that I am just about finished it and getting it ready to go...... I have an OPS 67 with a slide carb...The engine is new and it is tight at TDC... One question I have is..... what tricks or tips do you guys have for getting it started up the first time to break it in.... I have a sullivan 24 volt starter setup.... The second question I have is... will running it on a stand with water going through it for a tank of fuel or so help break it in or does it really need to be run under a load on the water? Any suggestions would be greatly appreciated Thanks Chuck

 

[SeanKewley]

Opinions on this vary to some degree, but the general concept is the same...

Run several tanks through it on the water under load. I run 5 tanks.

Set it pig rich when doing this and use a prop that you know will not over work the motor during the process.

Start to lean it out on the 4th or 5th tank.

 

[Bill Gibson]

Sean pretty much nailed it......thats the safe way to go......there is something that some racers do called heat cycling the motor, but unless there is someone with knowledge to help you do this, you could do more harm than good....if you do as Sean suggested, its a pretty safe bet that your motor will turn out good...just remember to start out RICH!

 

[julianconde]

i run like 6 tanks pig rich with a very small prop just enough to put a load on the engine and run it. after 6 tanks then i switch props and start to lean it out alittle bit at a time then by the end of the day im going all out...

 

[Al Hobbs]

Break the engine in using the fuel you will use at races.

Even though the factory put the engine together using oil, there maybe some dry spots. I go through my engines, set the clearances and make certain that all inner parts have a coating of castor oil. Before starting the engine the first time, remove the glow plug and turn the engine over to make certain that there is plenty of fuel going through the engine. Watch out that you don't get fuel in your eyes.

The OPS 67 and 80 can be so tight at the top, that a bit of fuel will keep it from turning over with the glow plug tight. After you have run some fuel through the engine with the glow plug out, pinch off the fuel and blow the engine out before putting the glow plug in.

You have made certain that fuel and oil have dispersed throughout the engine. You have made certain that there is plenty of fuel going through the needle valve. And you have made certain that the engine is not loaded with fuel.

Now start the engine. It should be on a rich setting and you may have to throttle up and down to keep it running. As long as it is rich you will be just fine. After a few tanks of fuel, you can start leaning the mixture.

I do run my in my engines out of the water the first few times. There is no water near me, so a new engine is heat cycled. I run it rich until the head is almost too hot to touch. Then I let the engine cool down before firing it up again. I do this several times at a rich setting, then I'm off to the next race and get my needle while on the water.

The key point is that you do not let the engine run lean when it is new. The con rod bushing will spin, get hot, and the rod will let go faster than you can believe.

Al Hobbs

 

[Duck899]

Break the engine in using the fuel you will use at races.

Even though the factory put the engine together using oil, there maybe some dry spots. I go through my engines, set the clearances and make certain that all inner parts have a coating of castor oil. Before starting the engine the first time, remove the glow plug and turn the engine over to make certain that there is plenty of fuel going through the engine. Watch out that you don't get fuel in your eyes.

The OPS 67 and 80 can be so tight at the top, that a bit of fuel will keep it from turning over with the glow plug tight. After you have run some fuel through the engine with the glow plug out, pinch off the fuel and blow the engine out before putting the glow plug in.

You have made certain that fuel and oil have dispersed throughout the engine. You have made certain that there is plenty of fuel going through the needle valve. And you have made certain that the engine is not loaded with fuel.

Now start the engine. It should be on a rich setting and you may have to throttle up and down to keep it running. As long as it is rich you will be just fine. After a few tanks of fuel, you can start leaning the mixture.

I do run my in my engines out of the water the first few times. There is no water near me, so a new engine is heat cycled. I run it rich until the head is almost too hot to touch. Then I let the engine cool down before firing it up again. I do this several times at a rich setting, then I'm off to the next race and get my needle while on the water.

The key point is that you do not let the engine run lean when it is new. The con rod bushing will spin, get hot, and the rod will let go faster than you can believe.

Al Hobbs

Al, I wish I had that picture of you holding 2 OS connecting rods (from those Muck OS 65's) up to your ears as earrings at Hermitage lake back in the 80's.....come a long ways huh?

 

[SeanKewley]

Here is a link to the heat cycle break in method that Al Hobbs referred to...

http://www.intlwaters.com/index.php?showtopic=39351&st=0

 

[Al Hobbs]

Yeah, those OS Max 65's let go faster than I could start swearing. The low side needle had some crap in it. I used the same carb on both engines. Bang, one let go. Bang, there went the other.

They were really nice engines prepared by John Shannon around 1980. I can't believe that 30 years has gone by so fast.

al Hobbs

 

[Jerry Wyss]

I did my first actual heat cycling today,, normally I run air cooled on my small o/b's so its in the water with those, but this was a customer TT o/b thats for IMPBA class 20 sport tunnel I think they call it so the thunder tiger had to look stock,, but it ain't really.

From reading the other "heat cycling" methods on here this one was quite different. I had cut a couple ports higher so I had to have a bunch of lube going thru with a Very rich mix. I had to have the water cooled head on there but didn't have any water going thru of course.

The modified carb was ballparked with the needles and the way I started the engine after a rich choke was to have the radio system on and set the transmitter on the table. The carb stayed open about 1/3rd and I grabbed the starter in one hand and the other pinched the fuel line to bring the engine to life.

I could control the running of the engine totally by pinching the fuel line,, the initial tanks of fuel I kept the speed lower but as the motor was braking in it wanted to digest that fuel more and the pinching became less.

The heat gun was used with the other hand and I brought the speed and temp up gradually thru the 7 tanks. If it built heat to the point of a runaway, I just brushed the back of my finger over the carb and the high speed rich needle took over again.

The highest temp I saw was 220 and it was really starting respond when I picked up and used the transmitter on the last tank. Now when I go to the pond the needle settings will be much closer and alot less rowing will have to be done. Plus the engine feels great, very free,. no plugs blown and it holds hand compression very well,, just like one of my aircooled motors.

There was no trauma involved , it was actually fun,, and if it can be fun to partially break-in an engine, That's a Big Deal!

 

[Andy Greene]

This was my 5th cycle today after 24 + oz.

Sounds like its happy

 

[Tony Newland]

Make sure when you shut it off to put the piston at BDC

#1 mistake made by old and new modelers

 

[julianconde]

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