8KCAB Gascolators and firewall fittings

Hiperbiper

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If you use the brass fittings with the single washer it might not line up at first but by adding washers (shims) you could definitely get it to seal with everything pointing the same way...
-or-

Gascolator mounted with Wag Aero fitting (mounting gascolator and sealing the firewall.
Then the above 90° close AN6 fitting to...
Chris
 

Big Ed

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Gascolator mounted with Wag Aero fitting (mounting gascolator and sealing the firewall.
Then the above 90° close AN6 fitting to...
Chris
That's the same thing I posted as an alternative. Great minds think alike.

swivel elbow.jpg

However, I am not sure which of the two fittings has the correct flare pitch. The one I posted has 45 degree flares, while I assume the Phenix AN6 fitting has 37 degree flares. As best I can tell, the brass elbow I removed has a 45 flare, which means so does the existing tube and nut on the line from the shutoff valve.

I don't know what flare the Wag Aero fitting has. I'll probably call them on Tuesday morning to find out. If it is AN standard 37 flare, I'll get the AN6 fitting you posted, and have the A&P fabricate a new line. If it is 45 degree, I'll go with the fitting I posted and the existing line.

Any problems with mixing brass and aluminum fittings?
 

Hiperbiper

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Only as far as thread pitch and diameter are concerned as well as the aforementioned flare angles.
I'm betting you'll end up with either the brass fitting/copper line or AN aluminum fitting/aluminum lines from end to end...trying to mix the two using adapters, etc. can run ya crazy 🤯. And the WA piece is AN6.
Chris
 

Big Ed

N50247 - '79 Super D
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Only as far as thread pitch and diameter are concerned as well as the aforementioned flare angles.
I'm betting you'll end up with either the brass fitting/copper line or AN aluminum fitting/aluminum lines from end to end...trying to mix the two using adapters, etc. can run ya crazy 🤯. And the WA piece is AN6.
Chris
From my limited understanding, the AN spec is always 37° flare, right?

In the picture below, the elbow on the left is the fitting I removed from the aircraft, on the backside of the firewall. The coupling on the right is a 45° flare from Home Depot. They look the same to me.

PXL_20210704_171217542.jpg

Based on that, the flared tube end and nut in the photo below should also be 45° flare. If the WAG firewall fitting is 37° flare, then no swivel elbow will be compatible with both fittings, and I am going to need a new line to the shutoff valve, no?

PXL_20210626_232305238 (1).jpg

Also just noticed the nut is marked with 3/8, which I think means it is not AN, though in theory it could still be JIC 37°.

PXL_20210626_232305238 (2).jpg
 
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Hiperbiper

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Ed,
Look closely at your side by side pics of the fittings.
On the left is an 37° nose and the thread pitch is much flatter. The 3/8 on the side of the nut denotes the size of tubing the fitting is for. And unfortunately, never the twain shall meet...
Chris
 

Big Ed

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Ed,
Look closely at your side by side pics of the fittings.
On the left is an 37° nose and the thread pitch is much flatter.
Chris
I don't think so. I think that is the light. I have held them side by side with backlight and stared at them for quite a while, and I cannot see a difference in angle. I have also held them end to end with the mating surfaces against each other. They both look like 45 to me. I will try to find something accurate to measure with.
 

Big Ed

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Grandpa to the rescue. He was chief mechanical engineer at the Delta Power Tools plant in Tupelo, MS for 50 years. I inherited his measuring instruments, among which is an angle gauge. The old fitting is definitely 45 degree flare:

PXL_20210704_193637600 (1).jpg
 
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Hiperbiper

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Grandpa to the rescue. My GF was chief mechanical engineer at the Delta Power Tools plant in Tupelo, MS for 50 years. I inherited his measuring instruments, among which is an angle gauge. The old fitting is definitely 45 degree flare:

View attachment 3838
I defer to your mechanical wizardry in place of my Mark 1 eyeball...🙃
 

Bob Turner

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The secret here is the early lightplanes used standard automotive fittings for everything. I can only assume Bellanca did that.
Most mechanics take one look at those fittings, and change everything over to 37 degrees and Aeroquip. That is okay, given that we have AC23-27, and it is a minor alteration. But that is why you will find 45 degree fittings on older airplanes - engineers back then were smart and cost-conscious.
 

Big Ed

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Went ahead and grabbed the fitting in stock at the local aviation parts store. It looks like a better design than the original parts. My A&P agrees. Going to order the phoenix swivel elbow fitting.

Still a bit confused by the flare angle. An AN nut is prescribed for the flare end. But I measured the flare with my angle gauge and it sure looks like 45 degrees to me. I am going to try to call the manufacturer tomorrow.
 

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Big Ed

N50247 - '79 Super D
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After wasting about $100 on fittings I won't use, we're going to go with the Texas Air Salvage fitting. That one takes the least amount of work to install. My A&P installed it and it looks pretty good. A bit of slack between the washer and the firewall. We'll stack another washer to take up the space, and seal it with some hi-temp RTV. Pictures to follow in a day or two.