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  • Header Welding Tips Needed

    My homemade headers finally bit the dust and now Ive got to make a new set. To make it a bit easier Im starting with a set of mild steel headman headers that fit well enough until they hit the frame. Does anyone have tips for welding techniques to avoid future cracking (which killed my previous stainless steel headers)? Ive got access to most all welding equipment (gas, MIG, TIG) but my success rate has been low with regards to cracking with MIG and TIG.
    BKB
    www.FBthrottlebodies.com
    Bruce K Bridges

  • #2

    Re: Header Welding Tips Needed

    Where are your cracks typically occurring?
    I'm still learning

    Comment


    • #3

      Re: Header Welding Tips Needed

      Bob,
      On the stainless headers I made they cracked just above the collector welds. The more I fixed em, the faster they cracked. The stainless steel was Chinese and of unknown alloy. I didnt purge them when I mig welded them originally which has been indicated by some as my bad. I havnt made a set of mild steel headers yet but I was hoping they were going to be more robust. Once I get em done Ill get them coated.
      www.FBthrottlebodies.com
      Bruce K Bridges

      Comment


      • #4

        Re: Header Welding Tips Needed

        I'd go with 16ga mild steel tubing, TIG welded with silicon bronze rod.
        If you want stainless tubing then get it from kooks or somebody that actually uses it.
        A Carter Carb Shop, sales and service

        Comment


        • #5

          Re: Header Welding Tips Needed

          I understand a MIG weld is very hard Maybe this has something to do with it. I don't have a lot of use full experience to really comment. I have always felt more comfortable gas welding mild steel exhaust pipes over MIG, being my own ability and have had good luck, don't recall any failures off hand.
          Tom
          Overdrive is overrated


          Comment


          • #6

            Re: Header Welding Tips Needed

            I'm also interested in hearing about people's first hand experience with welding SS for heat cycling applications.

            I think GH might be able to help, http://www.bangshift.com/forum/showt...h-Teaser-video!

            Seems like 304 and 321 are commonly used for headers.

            For my fellow material science nerds there's some decent general info in here: http://www.gowelding.com/met/austenitic.html

            Comment


            • #7

              Re: Header Welding Tips Needed

              I'd go with 16ga mild steel tubing, TIG welded with silicon bronze rod.
              If you want stainless tubing then get it from kooks or somebody that actually uses it.
              Im using 16 ga mild. TIG with silicon bronze sounds interesting. Not so much heat in the weld/braze. Im not messing with stainless headers for the time being. The dead ones started as a set of Chinese (SS Autochrome?) block huggers that I cut and pasted.
              www.FBthrottlebodies.com
              Bruce K Bridges

              Comment


              • #8

                Re: Header Welding Tips Needed

                Have you thought about slip joints for the collector?
                I'm still learning

                Comment


                • #9

                  Re: Header Welding Tips Needed

                  Have you thought about slip joints for the collector?
                  Bob, Ive got to lock things up pretty tight due to the EFI stuff, but I did think about it. Ive got a in-chassis header kit coming this week that is going to provide the donor tubing for the project but Im not convinced that Ill get it together without some angularity at the joints. Im not sure if Ill use the supplied collector yet due to space/clearance issues. This car has always been a PIA regarding exhaust systems.
                  www.FBthrottlebodies.com
                  Bruce K Bridges

                  Comment


                  • #10

                    Re: Header Welding Tips Needed

                    Bob,
                    On the stainless headers I made they cracked just above the collector welds. The more I fixed em, the faster they cracked. The stainless steel was Chinese and of unknown alloy. I didnt purge them when I mig welded them originally which has been indicated by some as my bad. I havnt made a set of mild steel headers yet but I was hoping they were going to be more robust. Once I get em done Ill get them coated.
                    I've made MANY sets of headers and did them for Chrysler when I worked in the exhaust lab....
                    I will bet yours broke at the heat effected zone(right next to the weld) which is normally when
                    you over heat the weld... I have built stainless and mild but mainly mild ... I've used silicon bronze
                    rod and standard mild rod... its still comes down to how much heat is applied that causes issues...
                    (it will crack with either if you apply too much heat)... silicon bronze has a bit more elasticity to it
                    over the mild steel rod.... if you MIG it I would use the "switch weld" process ... short hits on the
                    button to weld... run the heat a bit hotter but short bursts... this lets it cool more to reduce the temp
                    but IF you have a tig I would go with it... but keep the temp down and put a bit more of the weld on
                    top and not try to but it in deep.... I coat all the headrs I do for customers and for my own junk... this is a set of 3 step headers I built for my W-9 mopar... they've been on this engine for 8 years and look
                    the same... I built these so the primaries are within .1 in total difference
                    NOTE
                    I try to get 1 cyl volume before the first tangent of the bend.... but I know this cant occur all the time
                    (specs are from the valve so remember that)... ALSO... the collector length in MOST cases should be
                    about 16" long from the end of the primaries to get max torque(that number will only vary about 2" max)
                    Attached Files
                    Last edited by MR P-BODY; February 25th, 2013, 03:31 PM.

                    Comment


                    • #11

                      Re: Header Welding Tips Needed

                      Great tips, Mr. P!!

                      Have you ever tried to gas weld your headers? Should be a softer more ductile weld. But your HAZ would probably be bigger, correct?
                      I'm still learning

                      Comment


                      • #12

                        Re: Header Welding Tips Needed

                        cracking collector?
                        you need a hard collector.. or very aged one.

                        I have two headed for 30 years. one had a self made stalactite scraped off at the 20 year mark.

                        I then welded two stainless pipes to them making my own header. I don't even know what they are aymore, it can eat a grinder. once something is done to them today..there is no looking back to make beautiful.

                        they all must be soft at first, not sure how they get away with it.
                        I have found stainless collectors...never tried them.

                        one could try that tempering before weld. just needs an old oven 450-550F couple of hours. Slow cool.
                        Last edited by boxer3main; February 25th, 2013, 03:58 PM.
                        Atomization is excitement, not temperature.

                        Comment


                        • #13

                          Re: Header Welding Tips Needed

                          Mr P Body,
                          The voice of experience speaks! I think Im going to try mild steel rod and tig to start with based on everyones comments. Ill see if I cant pick some silicon bronze rod up as well. Ive never had a "proper" set of headers on the Jensen like your W9 units. The car has zip for room for a collector (flat floors). We'll see what the header kit inspires when it gets here.
                          Attached Files
                          www.FBthrottlebodies.com
                          Bruce K Bridges

                          Comment


                          • #14

                            Re: Header Welding Tips Needed

                            cracking collector?
                            you need a hard collector.. or very aged one.

                            I have two headed for 30 years. one had a self made stalactite scraped off at the 20 year mark.

                            I then welded two stainless pipes to them making my own header. I don't even know what they are aymore, it can eat a grinder. once something is done to them today..there is no looking back to make beautiful.

                            they all must be soft at first, not sure how they get away with it.
                            I have found stainless collectors...never tried them.

                            one could try that tempering before weld. just needs an old oven 450-550F couple of hours. Slow cool.
                            Boxer,
                            Weve got a honda powered high jumper buggy that slammed down on its stock honda 1982 collector and the motor mounts broke before the collector dented. Double walled impervium... Stuff was incredibly tough.
                            www.FBthrottlebodies.com
                            Bruce K Bridges

                            Comment


                            • #15

                              Re: Header Welding Tips Needed

                              Boxer,
                              Weve got a honda powered high jumper buggy that slammed down on its stock honda 1982 collector and the motor mounts broke before the collector dented. Double walled impervium... Stuff was incredibly tough.
                              it does exist..

                              I am still learning fresh into resembling hard and aged. aluminum as well.
                              I found old military videos on the tempering. So far an aluminum oil pump is singing like a bell..170k miles.

                              A pile of crap for steel can be anything you want.
                              a poor persons version can use 500F. 20 minutes. a whole different world.
                              Atomization is excitement, not temperature.

                              Comment

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