Club Cobra Gas-N Exhaust  

Go Back   Club Cobra > Club Cobra Tech Areas > Tech Tips

Welcome to Club Cobra!  The World's largest non biased Shelby Cobra related site!

  •  » Representation from nearly all Cobra/Daytona/GT40 manufacturers
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and nearly 1 million posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

Keith Craft Racing
Nevada Classics
MMG Superformance
Main Menu
Module Jump:
Nevada Classics
Nevada Classics
MMG Superformance
Keith Craft Racing
Advertise at CC
Banner Ad Rates
MMG Superformance
MMG Superformance
March 2021
S M T W T F S
  1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31      

Kirkham Motorsports

Like Tree4Likes
  • 2 Post By joyridin'
  • 2 Post By joyridin'

Reply
 
LinkBack Thread Tools Display Modes
  #1 (permalink)  
Old 05-02-2018, 09:17 PM
Texasdoc's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2012
Location: Keller, TX
Cobra Make, Engine: Lonestar Classics LS427. Self-built 408W, AFR 195 heads, Performer RPM Intake, Quick Fuel 750, 407rwhp, 479rwtq
Posts: 549
Not Ranked     
Default Any idea what metal this is? Welding options?

I bought this tank and need to do some modifications to it. I can't figure out what metal it is made from.

[IMG][/IMG]

I thought it was stainless but it is slightly magnetic. It also is rusted at the corners and where the builder welded on the fittings.

My best guess is that it is likely a 400 series stainless since it is slightly magnetic. I figure the welding was not appropriately gas shielded and destroyed the stainless-ness of the metal.

Since the stainless properties are already ruined (its starting to rust where it was welded when it was made), I can get some Stainless Flux Core wire (Blue Demon 308LFC-O) and do what I need to do. I can then paint the outside with Rustoleum and seal the inside of the tank to stop rust (KBS coatings tank sealer).

Any other thoughts?

Last edited by Texasdoc; 05-02-2018 at 09:20 PM..
Reply With Quote
Sponsored Links
Sponsored Links
  #2 (permalink)  
Old 05-03-2018, 03:58 AM
CC Member
Visit my Photo Gallery

 
Join Date: Jan 2010
Location: Adelaide, S A
Cobra Make, Engine: v10 ford
Posts: 172
Not Ranked     
Default

My thoughts, for what they are worth. Use a shielding gas as well as the flux core wire and give the tank coating a miss as it is another potential problem area if it doesn't bond. The rust concern although valid, is not a going to be a greater issue than what is there now, and should not grow as it is only caused by the welding heat that alloys the two metals.
My experience is only personal as I am not a certified welder, so feel free to disregard it.
Reply With Quote
  #3 (permalink)  
Old 05-03-2018, 05:37 AM
joyridin''s Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2009
Posts: 1,577
Not Ranked     
Default

If it is 400 series SS, it will be magnetic. Only 300 and some 200 series are non-magnetic. Most OEM exhaust systems are 400 series and they rust over time. The rust is no big issue as it would take years and years before it became unstable. I have seen 30 year old car exhausts in salty Ohio look fine and just the steel flanges rot off.

You will be fine using it. Not paint needed inside or outside. Nothing will rust and flake off like you see in steel.
legenmetals and Grubby like this.
Reply With Quote
  #4 (permalink)  
Old 05-03-2018, 09:23 AM
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2010
Location: San Antonio Valley Ca, ca
Cobra Make, Engine:
Posts: 1,259
Not Ranked     
Default

I would TIG weld it with a dual regulator. The second Argon line inside the tank set at around 10 cfm. Use a gaslense cup, 3/32 %02 Lanthanated and weld your heart out.
Reply With Quote
  #5 (permalink)  
Old 05-03-2018, 09:49 AM
Texasdoc's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2012
Location: Keller, TX
Cobra Make, Engine: Lonestar Classics LS427. Self-built 408W, AFR 195 heads, Performer RPM Intake, Quick Fuel 750, 407rwhp, 479rwtq
Posts: 549
Not Ranked     
Default

Yeah, I don't have a TIG. I have a MIG (or flux). I can't find anywhere to buy sheet stainless locally, so I'll have to order it online. I can get carbon steel to patch the big hole in the top at ACE or HD, but I'm not sure I want to mix metals. I may just have to find a local fabricator and pay them to TIG some stainless over it.
Reply With Quote
  #6 (permalink)  
Old 05-03-2018, 09:58 AM
CC Member
Visit my Photo Gallery

 
Join Date: Aug 2010
Location: San Antonio Valley Ca, ca
Cobra Make, Engine:
Posts: 1,259
Not Ranked     
Default

The problem you may find is that not many fab shops will weld on a gas tank. If I was to do it, I would first flush with plain water then add some dishwasher detergent ( that stuff cuts anything) Fill the tank with a gallon or so of water and shake the snot out of it. Rinse and repeat. Let it sun dry and then see if you have any hint of fuel smell. If so do it again. You would have to purge the tank of any fumes to weld it no matter how you do it.
If your going to try and mig weld it I would look into a dual shield wire and then still flow purge gas into the tank while welding.
On a guess by the time you buy wire and a stainless patch piece it would be cheaper to find someone to weld it at a shop. You will still have to have it super clean before they would even touch it. Be prepared to pay $5.00 or more per inch of weld. I would have a $50.00 minimum for just your reference.

Last edited by redmt; 05-03-2018 at 10:02 AM..
Reply With Quote
  #7 (permalink)  
Old 05-03-2018, 10:14 AM
legenmetals's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: May 2006
Location: El Cajon, ca
Cobra Make, Engine: contemporary(2) one with 427 sohc and one with 427 center oiler
Posts: 482
Not Ranked     
Default

The four hundred series stainless is an alloy of Chrome and steel and very little nickel, if any. The nickel is what reduces oxidation and causes the non-magnetic quality of 300 series stainless steel.

Weld it and coat it with paint.
Reply With Quote
  #8 (permalink)  
Old 05-03-2018, 01:41 PM
Texasdoc's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2012
Location: Keller, TX
Cobra Make, Engine: Lonestar Classics LS427. Self-built 408W, AFR 195 heads, Performer RPM Intake, Quick Fuel 750, 407rwhp, 479rwtq
Posts: 549
Not Ranked     
Default

Quote:
Originally Posted by legenmetals View Post
Weld it and coat it with paint.
If I did this, do I need to worry about rust on the inside?
Reply With Quote
  #9 (permalink)  
Old 05-03-2018, 02:20 PM
joyridin''s Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2009
Posts: 1,577
Not Ranked     
Default

Not if you use 400 series SS. It will not rust.

I have welded this material hundreds of times. I would not use flux core wire, but if you have a mig welder with a gas mix, grab some 400 series SS from Ebay, weld it up, and forget about it. You will never have a problem. I would not even worry about painting it unless you want it to look pretty.

I welded baffles in my tank a few years ago. Washed it out with soapy water (Dawn dishwashing liquid), then welded away. I had no problems whatsoever.
legenmetals and Jdata like this.
Reply With Quote
  #10 (permalink)  
Old 05-03-2018, 09:54 PM
Texasdoc's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2012
Location: Keller, TX
Cobra Make, Engine: Lonestar Classics LS427. Self-built 408W, AFR 195 heads, Performer RPM Intake, Quick Fuel 750, 407rwhp, 479rwtq
Posts: 549
Not Ranked     
Default

Since I don't need it to be magnetic, can I just use a 300/316 series stainless? I am still assuming this is 400 series - it is slightly magnetic. It may even just be steel. I'm not sure how to tell.

Edit: I found this on a welding website.

Quote:
If the tube is martensitic or ferritic, the magnet should stick just as well as it would to carbon steel. If it is only slightly attracted, I would guess you have austenitic tube there, probably 304. 304 is the most susceptable to martensite transformation during cold working. The strain placed on the tube while forming the sheet into a tube probably transformed some of the austenite into martensite which you are picking up with your magnet.
So, I think I probably have a 300 series stainless. Looking at the photo in the first post, the welds around the plugs have rusted a bit but the tank hasn't. There isn't any surface rust either. So I think the tank is stainless. Since a magnet barely sticks, I don't think it would be ferritic or martensitic.

I'm going to go buy a sheet of 300 and go to town. (Someone hold my beer....)

Last edited by Texasdoc; 05-03-2018 at 10:12 PM..
Reply With Quote
  #11 (permalink)  
Old 05-04-2018, 05:27 AM
joyridin''s Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2009
Posts: 1,577
Not Ranked     
Default

It will weld up fine. You will not have any issues.
Reply With Quote
  #12 (permalink)  
Old 05-04-2018, 10:08 AM
cycleguy55's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2014
Location: White City, SK
Cobra Make, Engine: West Coast, 460 CID
Posts: 2,477
Not Ranked     
Default

Quote:
Originally Posted by Texasdoc View Post
If I did this, do I need to worry about rust on the inside?
If you're concerned you could always coat it with POR-15 before you button it up and install it: https://www.por15.com/POR-15-Fuel-Tank-Repair-Kit
__________________
Brian
Reply With Quote
  #13 (permalink)  
Old 05-26-2018, 09:09 PM
CC Member
Visit my Photo Gallery

 
Join Date: Apr 2017
Location: Breckenridge, MN
Cobra Make, Engine:
Posts: 34
Send a message via AIM to Hoodabest
Not Ranked     
Default Don't do it!

Quote:
Originally Posted by cycleguy55 View Post
If you're concerned you could always coat it with POR-15 before you button it up and install it: https://www.por15.com/POR-15-Fuel-Tank-Repair-Kit
I really like por15 paint, but be skeptical of any gas tank sealer currently available to consumers. In my other life (vintage motorcycles) I've come to the conclusion that sealants fail most of the time and make a big mess.

Recommend PURGE the tank with argon (not co2) and tig weld. Inert purge prevents any scale from forming inside the tank. Good luck.
Reply With Quote
  #14 (permalink)  
Old 05-26-2018, 10:19 PM
Texasdoc's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2012
Location: Keller, TX
Cobra Make, Engine: Lonestar Classics LS427. Self-built 408W, AFR 195 heads, Performer RPM Intake, Quick Fuel 750, 407rwhp, 479rwtq
Posts: 549
Not Ranked     
Default

I purchased a sheet of 16g 304 stainless. Pre-cut to fit the hole I was patching. I used Blue Demon 308LFC-O flux core stainless welding wire that doesn't need shielding gas. It welded up well. Painted the outside then sealed the inside with KBS coatings tank sealer. I took my time and followed the directions explicitly. It turned out better than I thought it would. If it fails, I'll just get a fuel cell replacement.

Overall, I'm pleased with the results.
Reply With Quote
  #15 (permalink)  
Old 05-27-2018, 06:20 AM
GREENSNAKE's Avatar
CC Member
Visit my Photo Gallery

 
Join Date: Dec 1999
Location: ALTON IL. USA,
Posts: 159
Not Ranked     
Default

Stainless steel
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 10:33 PM.


Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the clubcobra.com forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by clubcobra.com and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. clubcobra.com forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting clubcobra.com. For full policy documentation refer to the following link: CC Policy
Links monetized by VigLink