miss

by russ white in General Tech Discussion 14 years ago

the 582 i have has about 12 hrs on it since rebuild ,,,, i am a new owner of such so anything i can learn to expidite the learning curve would be appreciated ,,,,,, the needle in the carbs was recently set to the number 4 slot [ i have checked and verified ],,,,, by previous owner ,,, egt is dead even at 11oo degrees and the plugs seem to be in a good color zone ,,,, water temps are in range and the engine runs like a swiss watch ,,, but when i pull her back to cruise after takeoff i feel a miss that is transmited that i pick up in the rudder pedals of all places,,, kind of like a thump or bang ,,,, only noticable between 5 and 6ooo rpm ,,,,,, plugs are new ,,,, oil injection seems ok ,,,starts great,,, any ideas ,, ?? and if i move the needle back to the third grove as per specs what can i expect to find [reduced egt ? ] or what thanks in advance for any suggestions ,,,,,, rusler

Re: miss

by Dave Brown » 14 years ago

Dave Brown

2 12 0

Hi Russ. Go ahead and try moving back to the 3rd notch as specified and see how it does. All you're going to do is richen it up by about 50Â°, which may make a difference, and is still within the ideal egt range.

Remember, the egt system is not all that accurate, and is best useable as a trend instrument. The plug color is the best gauge, but only for overall ranges. You may have a particular hot spot.

Dave

and with only 12 hours on it, it may still be breaking in. Another good reason for a little more richness.

Thank you said by: russ white

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Re: miss

by russ white » 14 years ago

russ white

1 1 0

thanks dave but my impression of it on the 4th grove is that it is already max rich,,,,, think i might be looking at re jetting ,,,,,, above my comfort level so i think it is time to turn a pro loose ,,,,,thanks once again,,,,, russ

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Re: miss

by Dave Brown » 14 years ago

Dave Brown

2 12 0

OK, you're talking about the lowest (bottom) clip position, not the top. Then adding some pitch in the prop will bring the egt's down. If you have standard jetting, this should work. What you should have is position 2 (summer), with egt's between 1050 and 1150 at cruise. Lower at WOT, around 950 to 1000, and probably a hot spot around 4000 rpm (avoid). Try to keep the water temp below 175.

Again, the plug color will tell the story. I would assume yours are light, to white? Try adding some pitch, but stay below max rpm at Wide Open Throttle in flight.

Dave

Thank you said by: russ white

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Re: miss

by Roger Lee » 14 years ago

Roger Lee

129 5.31k 5.1k

You can affect temps with too flat a pitch and too course a pitch prop. Too course will make temps climb higher faster, plus too course is not good for the engine. It loads it too heavily. Remember when you move a clip on the needle down that it effectually raises the needle up which allows more fuel to flow which makes the engine richer which shows up as a cooler EGT. Fuel in your 582 is the primary cooler and then right behind that is your regular coolant and then air flow.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Thank you said by: russ white

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Re: miss

by Dave Brown » 14 years ago

Dave Brown

2 12 0

You can affect temps with too flat a pitch and too course a pitch prop. Too course will make temps climb higher faster, plus too course is not good for the engine. It loads it too heavily. Remember when you move a clip on the needle down that it effectually raises the needle up which allows more fuel to flow which makes the engine richer which shows up as a cooler EGT. Fuel in your 582 is the primary cooler and then right behind that is your regular coolant and then air flow.

Hi Rog. Sorry, but I had to 'smite thee' for an incomplete info post. You're partially right, in that a coarser pitch will increase 'CHT temps', not EGT's. But you're right, you don't want to go too coarse on pitch.

Russ says his water temp is fine. His needle position is already at the richest setting (bottom clip position). Assuming he has factory jetting (since he only replaced the short block), adding Â½Âº to 1Âº pitch will bring the egt's down around 50-75Âº, and increase the CHT's some, and probably nothing on the water temp. The point here is to remain below max rpm range at WOT in flight. Static WOT (tied down) should be about 6150-6200 rpm. (Consider 6100 as cruise prop, and 6300 as climb prop, tested tied down.)

I've done several re-powers, both new and rebuilds. Each of them produced MORE power than the old engines, and needed a pitch increase to compensate, and keep the egt's in range. That pitch change increased cruise speeds at the old rpm's.

Anyway, we've answered Russ's basic question, and added more than he probably wants to think about. The vibration, or bang, could be a detonation impulse as he passes through a lean spot throttling back. Or simply something in the airframe shifting.

Dave

Now, we could talk about timing, which Â½Âº off either way will make a big difference, but that should be left to someone who knows what they're doing.

Thank you said by: russ white

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