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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


                              • #16

                                Re: Header Welding Tips Needed

                                The headers I showed were on my race car and it sets 4" off the ground... if you get into a problem
                                you can oval them... you will get a VERY small reduction in area(in most cases it wont hurt).. the 4"
                                is the lowest point in the front... I use to have the car at 3.5" off the ground but it was a PITA to load
                                on my trailer even with extended ramps
                                Attached Files

                                Comment


                                • #17

                                  Re: Header Welding Tips Needed

                                  My TIG skills are still 5th grade, but I've built multiple headers with a MIG and the set on the car are doing great at six years old. I did everything with the MIG except the flanges which were done by a good buddy, certified TIG welder as we did inner and outer. I also had them coated which is the greatest invention ever for exhaust tubing. I also built them as step headers which makes fabrication easier IMHO.

                                  For your super low profile set-up you may net benefit from a stepped design, but like Mr. P-Body i use the largest radius that will fit off the flange at as uniform a distance as possible. I couldn't get equal length but really pushed to get similar total bends in each primary along with a cone in the collector and putting the primaries into the collector in a circle by firing order. I really don't know if those things work but I copied stuff I saw at Burns Stainless.
                                  Drag Week 2012 - Winner Street Race Big Block Naturally Aspirated - Big hat no horses Drag Week 2013 - Watching the live feed Drag Week 2014 - Maybe I'll go faster with a 1000 fewer pounds?

                                  Comment


                                  • #18

                                    Re: Header Welding Tips Needed

                                    My TIG skills are still 5th grade, but I've built multiple headers with a MIG and the set on the car are doing great at six years old. I did everything with the MIG except the flanges which were done by a good buddy, certified TIG welder as we did inner and outer. I also had them coated which is the greatest invention ever for exhaust tubing. I also built them as step headers which makes fabrication easier IMHO.

                                    For your super low profile set-up you may net benefit from a stepped design, but like Mr. P-Body i use the largest radius that will fit off the flange at as uniform a distance as possible. I couldn't get equal length but really pushed to get similar total bends in each primary along with a cone in the collector and putting the primaries into the collector in a circle by firing order. I really don't know if those things work but I copied stuff I saw at Burns Stainless.
                                    I've never seen a HP increase by putting the primary tubes in a certain location when it
                                    comes to the dyno.... at least if the tubes were the same length... as soon as the tubes
                                    merge into the collector they are all equal and draw the same IF the temps were close...
                                    on a BIG percentage of headers I made I put a probe at 1" from the flange(all the probes
                                    were precisely 1" from the flange to monitor distribution of the manifold for A/F reasons)..
                                    you can see the bungs on my headers shown
                                    EDIT
                                    I actually made 2 sets of headers with equal tubes and mounted them in
                                    different locations for the same engine... when dynoed we seen zero difference
                                    but I was interested from some stuff I learned over the years..... thank you
                                    to Chrysler for all my dyno time.... and I spent a LOT of time doing header work
                                    over a 6 year period
                                    Last edited by MR P-BODY; February 25th, 2013, 06:28 PM.

                                    Comment


                                    • #19

                                      Re: Header Welding Tips Needed

                                      I watched my friend TIG weld headers for his turbo'ed 6.0 LS engine. They taped the ends of the tubing, then fed Argon gas into the pipe. This cleaned up the welds inside the pipe and also reduced the ridges.

                                      Now, I have seen headers crack because the exhaust does not give when the engine moves under load. Stainless is much more likely because it doesn't seem to be as flexible as mild steel. The exhaust on cars that run through the frame rails don't allow the pipes to move and that pulls the headers. That will cause the least flexible part of the exhaust to crack.
                                      BS'er formally known as Rebeldryver

                                      Resident Instigator

                                      sigpic

                                      Comment


                                      • #20

                                        Re: Header Welding Tips Needed

                                        I watched my friend TIG weld headers for his turbo'ed 6.0 LS engine. They taped the ends of the tubing, then fed Argon gas into the pipe. This cleaned up the welds inside the pipe and also reduced the ridges.

                                        Now, I have seen headers crack because the exhaust does not give when the engine moves under load. Stainless is much more likely because it doesn't seem to be as flexible as mild steel. The exhaust on cars that run through the frame rails don't allow the pipes to move and that pulls the headers. That will cause the least flexible part of the exhaust to crack.
                                        Stainless is basically a soft material BUT has a lot of abrasion in it(as in cutting it)... think of it
                                        this way... you wouldnt buy SS bolts to hold big loads but they look good on a intake and will
                                        hold that easily
                                        EDIT
                                        It can become brittle with too much heat on the welds... I built 1 set of headers out of 316SS
                                        and another 304SS ... if a car has a stainless exhaust its 304 which has a very good life span...
                                        Also... a few other things to do for the headers to live is... cut the flanges between any ports
                                        that you can... also make 1 hole larger than the bolt so it can slide and not buckle the flange
                                        as in(if you have 2 bolts per tube make 1 larger).. if 3 holes per set of tubes the center bolt
                                        wil be the normal size but the outers will be larger to allow slipage
                                        Last edited by MR P-BODY; February 25th, 2013, 08:40 PM.

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