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Surfacing AN sealing taper?

Winsten

Plastic
Joined
Aug 29, 2020
I have a friend that needs some 6AN (tighter tolerance JIC/SAE J514) fitting connections put in an extruded aluminum fuel rail. I am not anticipating making any money off of this, nor do I want to make any more of these ports in the future. The porting tool looks like ~$150 minimum. I was considering surfacing the taper to a small cusp height (time is not an issue really in this case, shouldn’t take long anyway) instead of buying the tool and leaving it at that, maybe cramming a steel fitting down inside to flatten it out. Should I consider turning a pin out of 4140HT and “burnishing” or pressing the cusps flat? Or are these ideas a recipe for disaster?

Any input is appreciated.
 

Mtndew

Diamond
Joined
Jun 7, 2012
Location
Michigan
I usually profile the port forms whenever I don't have a port tool. Usually with a bullnose end mill that has around a .005" corner radius or smaller.
It does take longer but in aluminum it shouldn't be that bad.
 

Winsten

Plastic
Joined
Aug 29, 2020
He better have a real good reason why $5 weld on bungs and a little tig time can't solve this problem.

I do not own a TIG, nor do I trust my welding enough to sell or give it to someone else. As for him, I’m unsure of his welding prowess as well.

Pretty sure it’s low pressure system ~200 PSI max (I’m not a car guy). For future reference, does anyone sell thread-in inserts that can be locked down with a pin?

Thanks for the reply mtndew, that puts me a bit at ease.
 

kustomizingkid

Titanium
Joined
Aug 2, 2010
Location
Minnesota
I do not own a TIG, nor do I trust my welding enough to sell or give it to someone else. As for him, I’m unsure of his welding prowess as well.

Pretty sure it’s low pressure system ~200 PSI max (I’m not a car guy). For future reference, does anyone sell thread-in inserts that can be locked down with a pin?

Thanks for the reply mtndew, that puts me a bit at ease.

Radium - Home Page
 

mmurray70

Hot Rolled
Joined
Jan 11, 2003
I surface them too, small bull nose. works perfect. dont worry about the bumps, just program small stepover and it will be fine.
 

Winsten

Plastic
Joined
Aug 29, 2020
I surface them too, small bull nose. works perfect. dont worry about the bumps, just program small stepover and it will be fine.

I figured with it being aluminum it wouldn’t matter too much, but I’d hate for him to lose pressure for my oversight. Thanks for the feedback
 

Rick Finsta

Stainless
Joined
Sep 27, 2017
I have surfaced them before but I do plenty of race car stuff so I just ended up going to Scientific Cutting Tools and getting the appropriate port tools and threadmills. They pay for themselves pretty quickly doing custom one off type stuff for guys doing things the right way.

For a guy not doing things the right way I would just throw an NPT thread on the end of the rail and have him screw in adapters.

The SAE specification has a surface finish call so just calculate your stepover to keep the scallop height short enough.

ETA: Pressure is usually about 45-75psig in a normally aspirated engine and up to 200psig+ in a boosted engine depending on application. Add the boost pressure to the base pressure since they will be running a referenced regulator (or blowing shit up).
 

Billy_C

Aluminum
Joined
Feb 18, 2022
I figured with it being aluminum it wouldn’t matter too much, but I’d hate for him to lose pressure for my oversight.

It's where the pressure is getting LOST TO that's the problem.

We do lots of these ports, both ISO and SAE for different industries. Obviously there is a right tool for the job but a profile with small stepover has gotten the job done many a time and will continue to be the go-to if someone needs there stuff next day and we don't have the tool or it's running production in another machine.
If you're worried, tell you bud to pressure test it on the bench first. Install the fuel rail, injectors, and intake. Cap all the open ports except one to connect a hose to. Throw some air pressure at it starting low and working your way up to 100 psi while checking all connections with some soapy water.
 

adammil1

Titanium
Joined
Mar 12, 2001
Location
New Haven, CT
If you want better sealing on a 37deg flare look up "Flare-o" it works great. Air-way and Brennan fitting both make them. I don't know the dimensions but that's probably your best bet.

As others have mentioned without knowing what you're trying to do probably a lot cheaper to buy, weld, modify something, drill out some SAE straight threads and use an F5OX or similar fitting rather than make your own flares.


Sent from my SM-J737V using Tapatalk
 

Winsten

Plastic
Joined
Aug 29, 2020
Thanks for all the replies guys. I’m not looking to get into automotive machining, I’m not confident enough in my knowledge of cars to do that professionally. I’ll surface it in this time around if he’s willing to foot the bill.

If he wasn’t a friend I probably would have just shied away from it. I’ve heard horror stories about making car parts from an older shop owner.
 








 
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