rcabj

using different kind of fuel alternately
would only disturb the tuning part...
and won't cause any damage to the motor..

Homebrewer

My Feedback: (8)

Correct, tuning is critical to engine longevity provided you use a quality fuel.

Celly013

When every you switch to a new fuel, idle a tank or 2 through the engine, and you'll be fine...

Homebrewer

My Feedback: (8)

If you understood ABC/ABN engines you would realize that idling is one of the worst things you can do to an engine because it may cause unnecessary wear of the engine. ABC engines need to operate between 240-275 degree temperature so that the internal engine components expand. IIf you run it cool at idle for extended periods or a rich setting and your engine will never expand--meaning that pinch you feel when you rotate your engine will wear away quicker.

For the life of me, I don't understand why RC Car folks insist on idling their engines for several tanks to break them in?

When you put new fuel in, start her up and let her warm up with a couple of full throttle bursts, adjust your needle settings so you are runing slightly rich (past the 4-2 stroke point but before the max lean rpm) and adjust your low end so you have a reliable idle and smooth transition. That's all you gotta do if you switch fuels which have more/less oil or more/less nitro.

Celly013

Well, I just went and checked the break-in manuals for 3 engines, and none of them make mention of idleing... So from now on... I'll use the phrase "The first 2 tanks should be Moderately Driven"

Good post...

i8tweety

My Feedback: (11)

There's been quite a few people recommending rebreaking in an engine when you change fuel.

This is complete non-sense. The break-in process is done to properly mate the piston and sleeve. This process can only be done once.

The rationalle for going through the process again is to ensure that you readjust the carburetor for the new fuel blend. The process should never take more than a couple of minutes.

When changing fuels, start by richening the high end needle upwards of a quarter turn on the high end needle (how much you need to richen the setting depends on the carburetor - set it how you would if you wanted to run around 150 degrees with your old fuel). Start driving your car - don't let it just idle because you will not be able to get a real idea of the temperature it will be at when you are running it. Check the temperature every 20 to 30 seconds (how often you check it depends on how quickly the temperature is changing). If it starts running too warm, richen it. After about a minute of running it, tune it just like you normally would.

kyokai2

Your engine will not be damaged by changing brands of fuel but could be damaged by using to high of a nitro percent without adding shims to the cylinder head. Usually anything above 25% requires shims. If you change between brands take it a little easy for 1 or 2 tanks so you can adjust to the different fuel mixture because no two fuels are exactly the same and watch your temps very close, different fuels run engines at different temps. Dont use airplane fuels at all, they are blended for engines that have a lot of clean cool air running over the head and we all know cars dont get a lot of air. You will hear of people saying they use airplane fuel but unless you are a chemist or very qualified in mixing glow fuel (which Im sure hardly anyone is) use only r/c car fuel and dont buy the cheap stuff go with o'donell, blue thunder, mugen, trinnity.

i8tweety

My Feedback: (11)

Kyokai2's right on the money about taking it easy for a couple of tanks while you adjust the engine to the different fuel mixture (I hope that's what you meant, because other than the PCRC fuel regulator systems I still have, I don't know of any engine that will adjust on their own).

Celly013

Which PCRC system are you using? Is it the EFR 801 ?

i8tweety

My Feedback: (11)

Actually, I've got 3 of them sitting in one of my pit boxes collecting dust. Yes, they are the EFR 801.

Celly013

3 of em? I'll give you 10$...

Those things are gold since they stopped making them... ;(

i8tweety

My Feedback: (11)

If you missed a "0" on the end, I still wouldn't get rid of them. Have you ever used them?

Celly013

Yeah, my '0' key must be sticking... I Have never used one, but read a bit about them. Apparently, the company sold the technology to someone else, and is no longer offering it to the public...

Whats your opinion of the system?

i8tweety

My Feedback: (11)

They worked great. The only problem is that you have to maintain them after every raceday (flush the mechanism with denatured alcohol to prevent castor from causing it to stick. The thermocouple is also relatively delicate. Overall, they work great.