Carb Drip

[SteveR]

Re: Carb Drip

My A-65 drips very slowly, probably would be measured in drops per day. That is on 100LL alone. I have no idea what kind of needle it is. How difficult is it to open the carb and figure it out, without messing up the carb adjustment?

[Richard Boyer]

Re: Carb Drip

It appears that I have the Derlin needle. The whole needle is a piece of white plastic.

Can you do anything with this? Do you lap a derlin needle?? Just replace it?

Richard Boyer
N95791

[NY86]

Re: Carb Drip

It appears that I have the Derlin needle. The whole needle is a piece of white plastic.

Yup, sounds like it. New ones are black. Is yours discolored? It could be quite old. I'd pull it out and look at the tip. if it is visibly worn, you should replace it. Does your float have the weight added to the arm outboard of the needle?

Can you do anything with this? Do you lap a derlin needle?? Just replace it?

If it's not worn, or you elect to replace it (spend lotsa money) you can lap it. I recall they specify some sort of lapping compound. We use Helmanns mayonase (no joke!). Lap it until you can see a very shiny ring where it contacts the seat.
If you replace it you will have to go through the float level setting routine (after you get it to seal!) Also, confirm you have the correct seat for the needle.

[SteveR]

Re: Carb Drip

How much do new needles & seats run, and what types are available today? I'm guessing the needle type IS something that should be verified before using MOGAS?

Thanks!

[Pearson]

Re: Carb Drip

If you change from one type of needle to another, you must change the seat.

I quite sure this has been discussed on this forum before. A search will probably turn up some valuable info for you.

[Richard Boyer]

Re: Carb Drip

There is a weight on the float.

Is the white bad?

Richard Boyer
N95791

[Richard Boyer]

Re: Carb Drip

I have a question I am a bit uneasy asking.

My carb is a NA-S3A1

Is this right?

[mulwyk]

Re: Carb Drip

Richard:
The NAS3A1 is a very common carb on the old Continentals.

Bob Gustafson

[M Towsley]

Re: Carb Drip

There are some excellent articles on the web about needles and seats. Don't forget to lap up and down, not 'round and 'round. One of the articles stated the mayonnaise helped remove the fuzzy hairs on the delrin once lapped. Cost of a steel needle and new seat is around ninety or so dollars from Fresno. That is where I got my latest needle and seat.

[barnstmr]

Re: Carb Drip

Speaking of prices of parts. Here is some recent info. I just received the following from Univair today. It is rainy here, plan to spend tomorrow in the shop for carburetor cleanup and re-assy.

----- Item Number 1 -----
Product #: ba-4108
Name: brackett filter element
Quantity: 1
Unit Price: $5.48
Item Total: $5.48
-----
----- Item Number 2 -----
Product #: 174s-22
Name: stromberg gasket
Quantity: 1
Unit Price: $9.74
Item Total: $9.74
-----
----- Item Number 3 -----
Product #: 384667
Name: stromberg gasket
Quantity: 1
Unit Price: $3.33
Item Total: $3.33
-----
----- Item Number 4 -----
Product #: p12999
Name: stromberg gasket
Quantity: 1
Unit Price: $2.58
Item Total: $2.58
-----
----- Item Number 5 -----
Product #: p16155
Name: stromberg gasket
Quantity: 1
Unit Price: $3.75
Item Total: $3.75
-----
----- Item Number 6 -----
Product #: p16160
Name: stromberg pin
Quantity: 1
Unit Price: $1.33
Item Total: $1.33
-----
----- Item Number 7 -----
Product #: p16166
Name: stromberg gasket
Quantity: 1
Unit Price: $0.23
Item Total: $0.23
-----
----- Item Number 8 -----
Product #: p16167
Name: stromberg gasket
Quantity: 1
Unit Price: $2.96
Item Total: $2.96
-----
----- Item Number 9 -----
Product #: p61033
Name: stromberg gasket
Quantity: 1
Unit Price: $2.71
Item Total: $2.71
-----
----- Item Number 10 -----
Product #: u85012-032
Name: piper gascolator gasket
Quantity: 4
Unit Price: $1.95
Item Total: $7.80
-----
Shipping Method: BEST WAY
Item Total: $39.91
Grand Total: $39.91

[barnstmr]

Re: Carb Drip

OH.... and they were selling the Delrin needle for $107. I didn't purchase needle as I have the stainless one... looks pretty good. I will lap with Crest mint toothpaste and finish lap with mayo and let you know how that works.

[NY86]

Re: Carb Drip

All 3 needles are available today. Steel or neoprene needles with seats run around $80.00 You don't always get the right, or even a good, seat...

Neoprene and Delrin needles use the same seat, what we call the radiused seat. Steel needles use a sharp edged seat. These are the ones that may be hard to find. I'm not sure if it's just a problem the supplier is unaware of or what.

White is not bad, just older.

I would not lap the Delrin needle with anything except mayo. The problem isn't really hairs, it's tooling marks, but that's moot. I chuck the seat in a drill press, put mayo on the needle, and hold it up there for 30 seconds at a time. Use a magnifier to look at it. When the shiny ring is "perfect" all the way around you're good to go.

On the other hand, lapping a steel needle with mayo is probably an exercise in futility. I use a paste of jewler's rouge in cutting oil.

The latest articles are at this site.

[M Towsley]

Re: Carb Drip

This has already probably been posted, but I utilized this sight with wonderful luck. Read the last part, it explains how to lap the delrin. That gentleman had trouble with the 'hairs' left over from lapping. If you can't find it just Google 'lapping delrin neddles'. The article can be found at: http://www.bowersflybaby.com/tech/st...20needles/.pdf

[NY86]

Re: Carb Drip

The article can be found at: http://www.bowersflybaby.com/tech/st...20needles/.pdf

The real link has a "1" in place of the "/" before ".pdf" However, as I pointed out before, that leads to an older, outdated copy of the article.

The reason I keep harping on this is that people keep calling me and asking for Lee...

[flyguy]

Re: Carb Drip

I have worked with large chunks of delrin in the aerospace business and on my own. Delrin has a characteristic that you can machine it with a sharp tool, but if you try to scrape or grind it it just deforms. That is to say it is tough and pliable. Similar to nylon, but a lot more so. If someone told me they were going to lap Delrin I would basically shake my head in wonder. What you can do I suspect is to heat it by friction and compress the rough spots into the form you want (if they are almost insignificant in the first place.) It is kinda like the process when polishing a glass mirror for a telescope. The glass actually smears into the imperfections. This is just my experience with delrin as I have never lapped a needle on anything that I remember.
Darryl