Carb Drip

[NY86]

Re: Carb Drip

Wow. I think Paulnuss' post is the most words on this subject I've ever seen where none of them were BS!

I'd like to add the following:

There is nothing wrong with the Delrin needle as long as it is properly installed with the correct seat. It is impervious to avgas and autogas and will likely remain leak free longer than the steel one.

There are "good neoprene" and "bad neoprene" needles. Problem is there's no way to tell them apart on the ground...

The article on the Bowers web site is a bootleg copy. The most current version, along with other usefull articles, can be found here.

Oh, yeah, one more thing, I don't think I've ever seen one with a yellow dot on it, although many have the mod...

[flyguy]

Re: Carb Drip

RE: Reply by "Paulnuss." Yep, that about covers it. Too bad all our gas (CA) has alcohol in it---yuk.
DC

[Pearson]

Re: Carb Drip

If one wanted to lap in a stainless needle, where do you get the compound needed? I have asked at three different auto parts stores and all I get is a blank stare.

[alwaysoar]

Re: Carb Drip

Forrest wrote you get an old tractor mechanic to "stake" the needle, then set it. I could look around to find an old tractor mechanic, but I'm wondering what it means to stake the needle. Is that like lapping, and if so can you use mild valve compound? I have the "good old" neoprene needle and count 2 drips a minute if I leave the fuel on. I'll live with that until I learn what stake means, and turn the fuel off in the meantime.
Ed@BTV VT
TF 527

[Marv]

Re: Carb Drip

I beleive staking the stainless needle is putting it in place and tapping it with a brass hammer to conform the needle to the seat. Then you can use toothpaste for the lapping. Forrest is this correct? Marv

[Forrest Barber]

Re: Carb Drip

You can lap it in , that puts it round, OR merely stand the needle up in the seat and "tap" it to get it to seat. Then the seat will conform to the needle. I have used either way, staking ,tapping ,smacking what ever is the quickest way. Only works with SS needle & seat , don't think the neoprene or delrin would take kindly to a hammer

[alwaysoar]

Re: Carb Drip

Thanks--Does it really take special skill, as in, do I really have to find an old tractor mechanic?

[mulwyk]

Re: Carb Drip

The old tractor mechanics I know...you wouldn't want them near your plane. Those boys do most of their work with a BIG hammer, if you know what I mean.

Bob Gustafson

[Forrest Barber]

Re: Carb Drip

Have a go at it! it is a bit of a tap.... watch out for those NEW ss needles that are now available if you don't watch out you will collapse the gap in the needle where it goes over the float, maybe put another little steel block in there when you tap it in... They seem to be softer than the original ones.
Soo much for needles, how is everybodys cork doing today?

[lfries]

Re: Carb Drip

Mine Still Floats. Sealed with clear model airplane dope 5 or 6 years ago

[Yellow Duck]

Re: Carb Drip

My problem is a little different. Doesn't leak;however, started loading up on idle when I land after flying. Just started doing this. though my primer might had not been secured, but it was. Going to clean my plugs and see if that might help. Other then that, guess will need to look at the carb.

[Gary Snell]

Re: Carb Drip

I've had alot of carbs with neoprene needles and haven't had a problem (yet??), but if I have one with SS and it doesn't leak that's even better. From what I have read, all the problems with the neoprene failures and mogas have been attributed to an aftermarket supplier that didn't use the correct composition of neoprene. Even fuels with alcohol shouldn't affect the good neoprene. Also think everyone should be aware that by design, the SS needle is supposed to have a different seat (believe there is less of a radius at the sealing interface). Seems the SS needles are easier to find than the seats that they go with and many needles get replaced without new seats. The SS needles don't seat well with seats made for neoprene.

Also thought I would share an experience I had with temporary engine stoppage on a steep climbout in a BC65 that I attribute to an incorrect needle/seat combination and low head pressure. Need to make sure that you have the proper needle travel (opening) which varies greatly between gravity feed systems vs. fuel pump systems. There are a host of different setting and jetting variances between this model carb for the A65 depending on applications. I would highly recommend that if one is apart to address float needle leakage that all specs are carefully checked for compatibility with the application.

[selje]

Re: Carb Drip

I've had alot of carbs with neoprene needles and haven't had a problem (yet??), but if I have one with SS and it doesn't leak that's even better. From what I have read, all the problems with the neoprene failures and mogas have been attributed to an aftermarket supplier that didn't use the correct composition of neoprene. Even fuels with alcohol shouldn't affect the good neoprene. Also think everyone should be aware that by design, the SS needle is supposed to have a different seat (believe there is less of a radius at the sealing interface). Seems the SS needles are easier to find than the seats that they go with and many needles get replaced without new seats. The SS needles don't seat well with seats made for neoprene.

Also thought I would share an experience I had with temporary engine stoppage on a steep climbout in a BC65 that I attribute to an incorrect needle/seat combination and low head pressure. Need to make sure that you have the proper needle travel (opening) which varies greatly between gravity feed systems vs. fuel pump systems. There are a host of different setting and jetting variances between this model carb for the A65 depending on applications. I would highly recommend that if one is apart to address float needle leakage that all specs are carefully checked for compatibility with the application.

You may want to check all the fuel hoses. I had a temporary engine stoppage at about 200 feet on climb out that caught back up when the nose was lowered. Did it a second time at about 400 ft when I tried to gain more altitude. Problem was that fuel line from tank to gasolator had delaminated and partially blocked fuel flow. There was enough flow for cruise but not enough for full power.

[Forrest Barber]

Re: Carb Drip

That was an old AD many years ago that you had to replace the fuel hose from gascolator to carb, it would delaminate & form a flap inside...Yes I still see the illegal ( bad) hose show up in the field... after 60 years The test is to roll a round ball through the hose both ways a couple times...

[VictorBravo]

Re: Carb Drip

It would seem to me that a modern urethane or silicone rubber replacement tip on the needle might solve the problem and not be affected by fuel, alcohol, etc. Has anyone thought of this? Owner produced part, "equal or better than original"???

That would not change the OTHER problems with alcohol in the fuel, affecting O-rings or other rubber seals. But I know there must be more modern silicone rubber compounds that are not eaten or swelled by alhohol and gas.

Bill