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Engine basics => Engine set up tips => Topic started by: frank mccune on October 27, 2015, 05:07:25 PM
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Hi All:
What would cause an engine to run rough, misfiring, while in level flight. When the plane is snapped into a maneuver, the engine breaks into a great 2 cycle throughout the maneuver. When the plane returns to level flight, the engine runs very roughly with a noticeable miss. No smooth 4 cycle is to be heard. I changed needle valve settings, glow plugs and prop sizes to no avail.
Any suggestions to cure this problem?
Tia,
Frank McCune
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Wot injun?
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Hi All:
What would cause an engine to run rough, misfiring, while in level flight. When the plane is snapped into a maneuver, the engine breaks into a great 2 cycle throughout the maneuver. When the plane returns to level flight, the engine runs very roughly with a noticeable miss. No smooth 4 cycle is to be heard. I changed needle valve settings, glow plugs and prop sizes to no avail.
Any suggestions to cure this problem?
Tia,
Frank McCune
Bad fuel will and could have caused that
Weak or cold glow plugs can cause that, even if they are brand new
Has the motor ran well before?
Having too much nitro in cold weather can cause this, if your turning the needle out more and more to slow the plane down
Too much load and pitch can cause that
if it has ran well before and something has changed we would need to know that
Randy
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Hi All:
Thanks for the prompt replies.
The engine is a 1970 OS MaxH .40S. This is the stunt engine with only a rear ball bearing and a plain front bearing.
The fuel runs great in other engines in weather that was 20 degrees warmer. The fuel was 11-11 with 6% more castor oil added and the nitro was 10%.
The temperature was 55 degrees down from the 77 degrees from the last time that it was flown.
The prop was a 11X6 that was replaced by a 11X5. Both wooden props.
The glow plugs were both "used" but ran well in other engines.
The engine ran like a Swiss watch the last time it was used. Same settings today as last flight.
The load is a Green Box Nobler that is light in weight.
I adjusted the needle valve a bit but I always got a great 4-2-4 run but the 4 cycle was rough. The next time that I fly this plane I will use a new glow plug as I have seen glow plugs go bad from the last time that they were used. ??????
Respectfully,
Frank McCune
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Hello All:
Kindly check out my post, "What makes an engine easy to start" in this section. Perhaps I have been contaminating my glow plugs with oil and producing difficult starting problems. Storage oil may be the cause of many of my starting problems. It is worth some research!
Best regards,
Frank MCCune
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"Storage oil" = "After-run oil", I'm guessing. What are you using? Also, what brand of glowplugs are you using? I'm devoted to avoiding Fox glowplugs at all costs; they suck. I don't think there is another brand that sucks as bad, tho I have not tried the Tower house brand. I don't know where they are made...but I do have suspicions. Who has used them...a lot? Yea or Nay? ??? Steve
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Hello Steve et.al.:
The after run oil that I now use is:
HUSKY Air Tool Oil
Sold at Lowe's
In the past I have used ATF with great results but I just wanted to try something different.
My lines are 60' eye to eye.
I am planning on using Fire Ball Standard RC plugs the next time and a different fuel!
I may install a Tom Lay OS. .40 that I have in my attic and I have never used. This is the one built on the OS.35 Stunt case with the ST .46 p&C installed. It is a bit lighter than the OS .40 so some nose weight will me added. I have never run this engine but a friend of mine had one and claimed that it would not do anything other than a 4 cycle.
In any case, I see that I have a bit or experimenting to do with this plane! Lol
Thanks for all of the replies,
Frank McCune