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Hello all....this is my first post. I’m a hobby welder that loves Rat Rods and have been using TIG for the last four years. My latest project is a 1937 Ford panel truck running a Chevy LS 6.0. I picked up a set of headers from CraigsList and was anxious to see how much modifications would be needed to make them fit. Drivers side bolted up with no problems. Passenger side was another story. The #4 cylinder tube turned straight down and ran directly into the motor mount. The only way to make it fit was to re-clock the tube 45* on the flange and weld it back up. I was doing just fine until I had to weld the tube back to the flange. I started running a bead and BAM! The dreaded air pockets filled the bead. I increased the amps and increased the gas and started the bead over again. Nothing changed. I could not get a smooth bead. I know I wasted an hour trying to get rid of the air pockets. I finally got it to be acceptable but was pretty ugly.
So my questions are:
1. What causes porosity in the first place?
2. Once it starts, what should be my next step?
3. Would it be best to grind everything off and start over?
There some kind of contamination within the shielding gas is usually the culprit, but it could also be unclean base metals. Where it is originating from is your job to find out. I had a "freak" situation a few weeks ago where a cheap gas lens was the culprit! I threw out all my 20-series small gas lens collet bodies!
When it starts, you stop immediately Now that you have lots of it, you definitely need to grind it out or replace a small section.
Try test welds on another ( known quality ) piece of tube or plate, using the exact same torch set up, tungsten, gas, etc as you were using when the problem started.
Were any of the above first time use items ? Were the headers MIG welder to the flange originally ? Tigging over MIG deposit can sometimes give that problem.
Just looking at your pic it looks as if you have the original MIG bead to weld the header to, or is that a before pic ? Did you bead blast / flapper wheel the surface coating off in the weld area ? Hi-temp coatings are best removed when welding .
As mentioned welding over previous Mig welds seems to create problems - also the flanges are generally flame cut with little clean up so extra care & cleaning inside & outside of the joint is needed & depending where the weld is - splitting the gas flow on edges & torch access / angle can be a problem - always worth making foil gas dams where possible - I find you have to be quick to add filler or porosity just keeps getting worse - not sure what your using but 309 while not always the logical 1st cjoice seems to be more forgiving on jobs such as this.
Now without actually wanting to start a fight I might add that trying to put a Chevy motor in a Ford truck is the biggest problem here ! it's just wrong - it's like mixing cross plys & radials !
noddybrian wrote:As mentioned welding ........................ on jobs such as this.
Now without actually wanting to start a fight I might add that trying to put a Chevy motor in a Ford truck is the biggest problem here ! it's just wrong - it's like mixing cross plys & radials !
Thank you Oscar and Kiwi2wheels for the response. I never realized that TIG welding on top of an existing MIG bead would cause a problem, but it sure did. These headers are ceramic coated steel and I believe some of the ceramic was still present in the nooks and crannies of the existing bead. Very hard to get a grinder in some of the tight spots. So between the MIG And the ceramic it was a disaster waiting to happen. I was using the basic mild steel 3/32 rod, 70s I think. Maybe I’ll re-grind and re-weld.
Noddybrian: you kinda pissed me off when you said putting a Chevy engine in a Ford truck is wrong. My blood is boiling. But I’ll keep it civil. Remember this is a welding forum not a hot rod forum. But from a hot rodders point of view it’s all about economics. My favorite junk yard is loaded with Chevy(GM) LS engines. A perfect start for a project build. The GM engineers copied all the good stuff from us hot rodders and came up with the LS engine. Not the case for the Ford Coyote engine. They are rare in a junk yard and if you do find one it won’t be cheap. So you can be a purest at heart but it all boils down to more bang for the buck to keep your build within budget.
diywrencher9 wrote:Noddybrian: you kinda pissed me off when you said putting a Chevy engine in a Ford truck is wrong.
Don't pay attention to noddybrian, people put Chevy engines in Fords all the time...now putting a Ford engine in a Chevy, that's sacrilege. Who would want a Ford engine? Not even the Ford owners want them...
diywrencher9 wrote:Noddybrian: you kinda pissed me off when you said putting a Chevy engine in a Ford truck is wrong. My blood is boiling. But I’ll keep it civil. Remember this is a welding forum not a hot rod forum.
Yeah, I think he was just making a tongue-in-cheek joke. Sometimes light-hearted context gets lost in text-based information sharing. It's really not that serious.
Oscar wrote:You only have yourself to blame for hogging old machinery that needs "TLC"
You're absolutely correct there, but remember, possession is 9/10ths of the law.
You have to be able to get it home in order to even use it!
Me and a friend were laughing today, he's also got a lot of machines and he first said, a well tooled machine is worth it's weight in gold, but that once he kicks the bucket his wife will hire someone to just get it out of the garage. So we made a pact together, whoever dies first the other gets first shot at the machines from our widow.
Now that you have lots of it, you definitely need to grind it out or replace a small section.
