Silverhawk fittings

[Don at Airflow]

Yes your picture is correct Bob. AN815-4 will work as an O-ring fitting with the addition of an O-ring at the base of the threads. The correct O-ring boss for use with AN fittings is MS33649 (that?s what we use when we manufacture our fuel injection regulator bodies), although in a pinch if all you have is a JIC port tool it will work.

When you install a 90 or 45 degree fitting (AN833 or AN837) you would use a bulkhead fitting with the jam nut (AN924), but there again you can use a hydraulic O-ring boss to JIC fitting. These have a washer abs jam nut made part of the fitting to seat the O-ring in the boss port. That?s what Precision uses for their 90-degree inlet fitting and some metered outlet fittings.


Don

[Lars]

I just talked to Don Rivera. I got a little education on the nuances of o-ring fittings in aircraft fuel systems. Go with the fitting he advises. There are subtle differences in the o-ring chamfer from SAE J514 to MS33649.

I'll add one more thing: don't overtighten these fittings, in any case. The o-ring is sealed once the fitting is bottomed. The spec on Precision Airmotive's site says 45-50 in-lb for this fitting.

Everything everyone has said about Don is true. What a nice guy. He spent 10 minutes on the phone with me today answering my questions and sharing arcane details about fitting design. Thanks, Don!

[8CW]

this is why I have chosen to use Airflow Performance Fuel Injection on my bird...

[LettersFromFlyoverCountry]

Originally Posted by Don at Airflow

JIC port tool

What is a JIC port tool?

[Lars]

Originally Posted by Bob Collins

What is a JIC port tool?

See this page for an example. It's a cutting tool, typically used in a milling machine, to create some of the ports described by the arcane mil specs we are throwing around

[LettersFromFlyoverCountry]

You know, I read some of the conversations some of you have in this thread and elsewhere and I think, "I'm really not smart enough to build one of these."

[pazmanyflyer]

Originally Posted by Bob Collins

You know, I read some of the conversations some of you have in this thread and elsewhere and I think, "I'm really not smart enough to build one of these."

That's not true Bob. You're more than capable. To be honest I get a little frustrated with you when you talk like that. Not just you but others too. You must remember that you just don't have all the experiences everyone else has all wrapped up in one person. That's all.

[Brantel]

That's right.. No one person has all the answers around these things! That's what makes the RV community great!

[C-GRVT]

I'm also installing a vertical induction IO-360, SilverHawk system, and have not yet run the fuel lines, so followed this thread with interest. I, too, am left with questions.
This is not at all a criticism of those responding, but rather reflects the vast gulf between what, say, Don at AirFlow knows, and what I know about fuel injection systems and aircraft fittings (nothing!).
Your question about whether the fitting (pictured) would work, with an 0-ring added, for example. The answer was yes, but I wonder - what type of 0-ring? Rather important, but presumably so obvious, no need to mention it.
Or, in a few spots (mechanical fuel pump, for example, or constant speed oil line) there is a fitting with an o-ring and a lock nut. How is that oriented and tightened?! Lars says the "o-ring is sealed once the fitting is bottomed". Is he talking about that kind of fitting? What does "bottomed" mean? I screw the thing in to the correct orientation, and it is not "bottomed" (I can still turn the whole thing) but I can then tighten up the lock nut against the 0-ring. Is that right? How tight?
Very grateful that people who know about these things respond to these posts. Please, when you do, assume that there are readers who really do know almost nothing and craft your responses accordingly!
This question of Bob's is directly connected to the very valuable recent Van's comment on safety and related thread. We all have to get the firewall forward stuff right!
Bill Brooks
Ottawa, Canada
RV-6A finishing kit

[Don at Airflow]

Bill you are correct in your assessment. There are people frequenting this forum with knowledge in specific areas. The beauty of this is you can tap the brainpower of many people, or as many manufactures are listed on Doug?s site, just give them a call. As with our company we are willing to help out (within reason) people?s questions on fuel system installation issues as well as troubleshooting the fuel system in your installation. You never know where this exchange of information may lead, but for us, hopefully to another sale of our equipment and another satisfied customer. Sometimes the answer you want to hear is not the answer we give, but in our case we deal in facts. And of course sometimes there is more than one correct answer.

For whatever reason what seems common and straight forward mystifies some people. For instance the bulkhead fitting you mentioned. We see these fittings installed incorrectly all the time. Take a look at the fitting and you will see a smooth section between the threads on the part of the fitting that is suppose to screw into the port. The smooth section is where the O-ring is supposed to be when the fitting is seated in the port. If you screw the fitting in to far the O-ring will get cut on the threads of the fitting next to the jam nut, conversely if you don?t screw the fitting into the port far enough the O-ring will get cut on the first set of threads on the fitting. It?s pretty simple to see if you take a look at the fitting and the port. Typically there is enough smooth section on the fitting to allow 1 ? turns of the fitting when the fitting is seated in its correct position to not cut the O-ring. In any case the fitting is not "bottomed" as this will surely cut the O-ring. As far as the material of the O-ring is concerned the manufacture should specify what material is to be used based on the conditions and service the part is in. If you don?t know then call the manufacture or get a copy of a Parker O-ring handbook. There is plenty of engineering information in this document to inform you of the correct materials and installation methods.

Hope this helps.

Don