| Author | Message | ||
| Henryk (Henryk)
Member Username: Henryk Post Number: 589 Registered: 8-2001 |
Paul: Agreed, TIG is generally stronger than MIG, but I have seen good MIG and bad TIG welds, and vis-versa. As you know, preparation is evrything!!!!!! My thought was that this was not a structural member, in need of great strenght. Besides, this is a 77 308.....23 years old, with it's first crack; I feel that any welding will last a long time....IMO. | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 164 Registered: 12-2002 |
Henryk Congratulations on the Miller 350 � a nice bit of kit! No one can deny that MIG welding is way faster than TIG � But a TIG weld will always win hands down when it comes to the quality of the weld, its not just about aesthetics. Surely you must agree that a TIG weld is stronger than a MIG weld? I have seen many MIG welding failures due to poor penetration. Some thing that you very rarely get with TIG welds. Sorry if this is getting a passionate about welding  but I was just concerned about the fact that Terry might have to get it repaired once again some time in the future! Paul | ||
| Terry Springer (Tspringer)
Member Username: Tspringer Post Number: 416 Registered: 4-2002 |
Peter, The problem is that one end of the crack in this case cannot be reached by a drill bit. Or at least it will be very tough to reach. Im going to take it by some local welders and get opinions today, will post results. Peter: I was told you may have some of the air injection manifold plugs available? Im looking for some... Terry | ||
| '75 308 GT4 (Peter)
Advanced Member Username: Peter Post Number: 2608 Registered: 12-2000 |
My secret to stress-relieving cracks is to drill the ends of them, then weld (I'm a TIG guy). It'll never crack again... | ||
| Henryk (Henryk)
Member Username: Henryk Post Number: 585 Registered: 8-2001 |
Paul: I just bought a new Miller 350 with pulsed TIG. Pulsing is generally used for thin material......exhaust headers are not considered thin, by TIG standards. Those pencil heads you are referring to do exist, however, these are used with 0.040 inch tungsten, which is used with similar size wire........used to weld very thin material. Don't get me wrong: either method is OK, however, MIG is just as good and MUCH faster.....I was just trying to save Terry some money......MIG costs much less than TIG. The only reason one would use TIG is to get a beautiful looking weld.....something that is not of a concern from what I see. A good MIG weld would look more than adequate. Today,I just completed welding a covering, I cut from my pre-cats, to remove the inside material......MIG welded the whole cover back on (3X5 inches long)in 10 minutes. | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 163 Registered: 12-2002 |
Henry, MIG is also a possibility but TIG torches are available these days no bigger than a pen! And using a pulsed TIG offers more control when welding thin materials. Terry, What I would suggest is that if you do get them to weld it up, ask them to weld in a inch long gusset between the two pipes. This will help the strength of the problem area no end. Paul | ||
| Henryk (Henryk)
Member Username: Henryk Post Number: 584 Registered: 8-2001 |
I think TIG welding would be very tricky, due to the "difficult to get at" location. I would recomend MIG welding. Here the wire can be lenghtened to reach this tough area. MIG welding would also be very quick. | ||
| Paul Hill (348paul)
Junior Member Username: 348paul Post Number: 162 Registered: 12-2002 |
Matt, Are the headers really out of 304 stainless? � I would have thought they would have been made out of 321 as this is the preferred material to use on High performance headers, Turbo systems etc. as it has more resistance to high temperature fatigue. If they are out of 321 I always use 347 filler rods on this grade. Paul | ||
| Terry Springer (Tspringer)
Member Username: Tspringer Post Number: 415 Registered: 4-2002 |
The only thing that worries me about getting this repaired is that the crack extends further around from what is visible in the photos. Im not sure it will be possible to get a welding tip onto all of the crack and Im not sure if its possible to extend any weld repair beyond what can be directly reached. | ||
| Matt Morgan (Kermit)
Junior Member Username: Kermit Post Number: 116 Registered: 8-2001 |
Yes, that is easily repairable by any competent TIG ( used to be called Heliarc) welder. I would recommend 308 Stainless filler rod, makeing sure all is clean, and that the inside is purged(filled with inert gas) to insure no contamination from the atmosphere which will reduce quality. | ||
| Terry Springer (Tspringer)
Member Username: Tspringer Post Number: 414 Registered: 4-2002 |
I got my headers off, and cut off all the heat shielding. My original hypothesis of leaking exhaust around the front header CO tubes may still be true.... but I located a definte exhaust leak inside the rear heat shield. One header pipe is cracked about 1 inch where the pipe does the 4 into 1 merge. The crack is in a very tough spot, the edge of the weld where the pipe does the merge. The crack is visible but is on the side of the pipe running inside all the other pipes. It will be tough to reach it all to weld a repair.... it will definitely take a talented torch man! What do you guys think, is this repairable?   Anyone know such an artist in Atlanta? Terry |