when is it too lean?
04-08-2016, 01:39 PM
#16
All the guys at your club use temperature guns, but you, a self-admitted nitro noob, think they're useless?
The temperature gun is not useless -- the temperature gun is what lets you achieve consistent tuning results, because a ringless engine relies on a consistent amount of thermal expansion (i.e. running at a consistent temperature) to achieve a proper combustion seal.
Set the idle gap to about 1mm (the space you can see when you look at the throttle valve when the engine is idling), tune the HSN to achieve an average running temperature of about 230-250F, and tune the LSN to achieve a decent idle that doesn't choke the engine (too rich) or cause it to fast-idle for more than a couple seconds (too lean).
A rich HSN will NEVER cook the engine. Running lean is what makes an engine overheat. Excess fuel acts as disposable coolant.
The temperature gun is not useless -- the temperature gun is what lets you achieve consistent tuning results, because a ringless engine relies on a consistent amount of thermal expansion (i.e. running at a consistent temperature) to achieve a proper combustion seal.
Set the idle gap to about 1mm (the space you can see when you look at the throttle valve when the engine is idling), tune the HSN to achieve an average running temperature of about 230-250F, and tune the LSN to achieve a decent idle that doesn't choke the engine (too rich) or cause it to fast-idle for more than a couple seconds (too lean).
A rich HSN will NEVER cook the engine. Running lean is what makes an engine overheat. Excess fuel acts as disposable coolant.
04-08-2016, 02:23 PM
#17
Temp guns are reliable if you use the same one ! Engine doesn't care if its 235 or 236 or 237 degrees... If your tune is right by sound and sight , and you hit it with a temp gun and it says 237 , then the rest of the day that temp gun will show you if your letting temps go up or down , and by how many degrees. If a temp gun cant be trusted to at least show that , somebody has bought the cheapest POS they could find. We are measuring the temp of model engine on its cooling head . Not exactly the most precise and scientific process .
04-08-2016, 06:22 PM
#19
Anybody who thinks the spit test is somehow more accurate is a fool. They might be a lucky fool, but a fool nonetheless. The boiling temperature of spit varies from one "sample" to the next, because the water content is never exactly the same.
As for tuning by sound, that's a good way to make sure you've got the ignition timing correct, and the ignition timing does affect the temperature of the engine, but the sound doesn't tell you how hot the engine is -- and it's the engine temperature that determines whether it will wear prematurely or not.
04-09-2016, 10:54 AM
#20
As wittyname said, it doesn't matter if one temp gun reads a couple degrees high or low, all that matters is that it reads consistently. That's easy enough to determine; boil a pot of water, shut off the heat, and take multiple readings above the water; if the temp gun is good, it should read +/- 1 degree over multiple readings.
Anybody who thinks the spit test is somehow more accurate is a fool. They might be a lucky fool, but a fool nonetheless. The boiling temperature of spit varies from one "sample" to the next, because the water content is never exactly the same.
As for tuning by sound, that's a good way to make sure you've got the ignition timing correct, and the ignition timing does affect the temperature of the engine, but the sound doesn't tell you how hot the engine is -- and it's the engine temperature that determines whether it will wear prematurely or not.
Anybody who thinks the spit test is somehow more accurate is a fool. They might be a lucky fool, but a fool nonetheless. The boiling temperature of spit varies from one "sample" to the next, because the water content is never exactly the same.
As for tuning by sound, that's a good way to make sure you've got the ignition timing correct, and the ignition timing does affect the temperature of the engine, but the sound doesn't tell you how hot the engine is -- and it's the engine temperature that determines whether it will wear prematurely or not.
Are you telling me that if I put a less efficient cooling head on an engine, it is more likely to wear out.
Also, turning needles on the carb doesn't affect ignition timing
. It affects the tune.
04-09-2016, 07:00 PM
#21
Temperature is important in another regard too . when is the engine not getting hot enough for proper expansion internally. On a cold day , you can have a engine spot on , and its not getting over say 160 to 180. That to me isn't hot enough. Thoughts on that side of it ?
04-09-2016, 07:54 PM
#23
Running an engine "hot" doesn't wear it out. Running an engine lean does. No question about that one.
Are you telling me that if I put a less efficient cooling head on an engine, it is more likely to wear out.
Also, turning needles on the carb doesn't affect ignition timing. It affects the tune.
Are you telling me that if I put a less efficient cooling head on an engine, it is more likely to wear out.
Also, turning needles on the carb doesn't affect ignition timing
. It affects the tune.
04-10-2016, 12:43 AM
#24
That moment when you realize that the internet gives everyone the chance to be an expert...
04-10-2016, 11:12 PM
#26
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