trouble with advancing throttle

[dfcpac]

i have a a65-8 in my champ. recently when i advance the throttle foreward about 3/4 to full throttle it starts running ruff. get to full throttle it smooths out. this is only on take off, in the air it's fine. is it in the carb? where would i start looking? i did notice the carb looks a little moist

thanks
dan carley
n9176l

[Paul Agaliotis]

Dan,
With the cooling weather the carburetor may have leaned a little bit. Try using carb heat on TO to see if it returns to normal. If it does just rich-en it up a bit. If your plane always had this problem this procedure won't help.
Paul

[dfcpac]

thanks paul i'll give it a try

dan

[CptKelly]

My advice is to fix it on the ground. If an engine isn't running well, flying it isn't the answer. They rarely fix themselves in the air, and it gets very quiet when the big fan stops turning....

Mike

[MikeB]

Dan,
I don't know where you're located but the 'leaning out condition' is very common when the weather gets colder (at least up here in the northwoods). Basically the reason being (assuming you have a Stromberg) there is no accelerator pump and the engine requires more fuel when cold. Of course, you also have no choke to enrich the mixture either. Using the carb heat enriches the mixture until the engine warms up. Leaving the primer out slightly also helps but don't forget to lock it in before taking off.

MikeB

[rkittine]

Must have clicked on New Topic as my response showed up as a new post - See - Rough Engine

[dfcpac]

going to take the cowl off today and look around. it sounds to me like a carb. problem. maybe a intake tube. any idea's where to look?

dan carley

[CptKelly]

Check the bolts holding the carb on to the spider. I've seen them fall off while in use, and suck air, making a very lean mixture.

Mike

[dfcpac]

i went though the whole carb. the 2 bolts that hold the manifold to the engine, the front one was loose, plus some of the clamps on the intake manifold rubbers were a little loose too. hopefully that was the problem. if it's nice tomorrow i'll give it a try.

dan carley

[dfcpac]

went flying today, same thing. rought just past mid throttle, if i use carb.. heat it works fine. this never happened before in the past yrs. does anyone know bill pancakes phone number or email

i think it's best to send the carb. out and have it rebuilt

dan carley

[Flynlow]

Dan, I recently went through something similar. It was rough just off of idle, then would smooth out after that. It would happen on the ground, but started in flight. Phil and I took the carb off and took it to the A&P. He said it was pretty dirty and cleaned it. Also, the rubber tip on the needle was showing some wear. He recommended replacing it with a new needle that is solid metal and doesn't have the rubber tip. I think he's still waiting on it to come in, but I'm looking forward to some long, trouble-free flying after this!

[badger bob]

i had some thing like this with my 7aca (65-8) it ran ruff till i hit full throttel then smoothed out. it turned out to be that the primer was not locked down and it was runing rich. Dan keep that 7aca running theres not many still flying. Bob

[Griphos]

Dan, any luck fixing this problem? I have it now too. Except I have it in the air while flying. Pull back to about 2100 to 1800 and she sputters and coughs a bit, running rough. It's the airplane that Jack is talking about a couple of posts above. We had the carb cleaned and a new needle and seat installed. That moved the rough range up the tach (from just above idle to about 1700-2100). I don't think it's cold weather. It's only in the 50s and she ran just fine last winter.

[Griphos]

Update: I flew her again today. Before flying I adjusted the idle mixture screw a little at a time until she ran well on the ground, both advancing and retarding throttle rapidly. That required a full turn rich, and she's now at 3 turns from full lean.

She ran better in the air, but still has a problem in a 200 rpm range between 1950 rpm and 2150 rpm. At 2000, she'll cough and sputter. Pulling on carb heat helped at first, when the engine was cooler still (ambient was upper 50s/lower 60s), but less so as she warmed up. In fact, in the first ten minutes or so, when I pulled carb heat, rpms actually climbed 50 or so and she smoothed out (in that rough band). I could advance the throttle smartly without hesitation, and retard it quickly without backfiring. In fact, backfiring on glide was almost eliminated. Flew the pattern great. I could fly around with carb heat off at 1700-1900 and just purr along, but push it a little more and she ran rough. Push it past 2200 and she settled down and ran like a top.

Any ideas appreciated. I'm deeply puzzled. I'm going to advance the idle set screw one half turn more the next time I fly to see if it makes any difference.

[dfcpac]

i sent my carb. to bill pancake, he's going to look it over. it has to be a carb problem

dan