The Cessna 120-140 Association Forum

A 140 just sold on our field and I was giving it a once over, noticed the fitting off the gascolator to the carb and it was the usual kluge of AN fittings to 'emulate' the original AN826 fitting.

So, one end of the original fiting is a pipe thread into the reducer to the gascolator body (4? pipe thread).
One end is towards the carb and it's a compression configuration (6?)
The 'T' offshoot is a 2D (fits the flared end of the copper tubing).

I keep trying to find a better combination of AN fittings to negate the rather long and piecemeal things I've seen (mine included, a kindly Club member sent me a servicable proper used one).

Here's what should be used... And here's a typical 'kluge'... The search is on for a less 'klugy' combination once I better understand the AN designations. I've found some 'reducers' that are out of the ordinary but am having a hard time deciphering this chart if anyone cares to chime in...

Not sure what you're looking for. The AN894 fitting would allow you to connect the fittings on the right in your photos to the tubing for the primer, in other words, to convert the right fitting to the center one.

When I was running a parts business 15 years ago I wrestled with this very issue, and, short of having one manufactured (and getting it approved) the hodgepodge of parts like in your second photo is as good as you can get. (Well, except for mixing brass and aluminum.)

Thinking like an 826-6D and putting the reducer on the primer lead, on the chart there is an AN 894D-04-02 reducer that I thought might work. Basically trying to shorten things up and make cleaner with less parts. I just don't have a good grasp of these AN fittings.

OK, you're making my head hurt...

IIRC, there is a reducing bushing in the gascolator outlet, from #6 pipe to #4 pipe. You may be able to use the AN826-6 without the reducer on that end. I think the -6 tubing fitting should mate to the hose to the carb as is. You need to reduce the other -6 tubing fitting to -2. Problem is the AN894 doesn't come in -6-2. You could stack -6-4 and -4-2 but you're approaching hodgepodge again.

AN826 is the same as MS20826. The "dash number" is the fitting size in 1/16ths of an inch, so, -6 is 6/16 or 3/8". The "D" on the end means it's aluminum. Otherwise it would be brass. AN826-6-4-2 means each of the three threads are different.

The "dash number" is the fitting size in 1/16ths of an inch, so, -6 is 6/16 or 3/8". The "D" on the end means it's aluminum.

Ah, that's what I needed to know to make it a little clearer.

So an AN826-6-4-2D, the '6' is the end that goes towards the carb. That's the 'tube' thread. The '4' is the part that goes towards the gascolator and it's reducer, 1/4 x 18 pipe thread. The '2' is the pesky 'T' that goes to the primer line.

OK, you're making my head hurt...

I went thru this about 20 years ago also, just a glutton for punishment I guess....

I want to see if I can help the new owner make his 'kluge' a little better. Discovered the AN894 fittings recently. Not looking promising so far....

How about this idea, get rid of the reducer on the gascolator and install this...
Then get one of these from Univair for the primer line....

Just an idea-

6597 wrote: ↑Fri Oct 10, 2025 2:50 amJust an idea-

Wow! You may be on to something there. The only problem I can see is if the part is not really an "AN" part. (I suspect it isn't.)

Another possibility is to use a coupler like that, genuine "AN" (AN816-6), and drill and tap it for the adapter for the primer line. The problem there is the flat area might not be big enough for the hole for the primer fitting.

Yeah, my original observation was that the 'kluge' arrangements were adding a 'torque' to the fitting going into the gascolator. The original design was short and didn't have that kind of leverage. Maybe not an issue, but an observation, hence the quest for something more compact.

I have no idea what the specs are on that AN6 hex fitting but I"ll work on it...