welding TFX cast block

need to repair small crack in pan rail,do I use a big "cup" as to displace a larger weld area? I tried a #7 but seems as soon as I puddle the block, the add filler .........it contaminates are like right now............

 

I would recomend eching compound to clean the block where you are welding, i used some thing with a X at the end of the name ,it was pink color, and would bubbel up then wipe off and weld. forgot name, ( old age)yes use a big cup, and big torch

 

Well this is what I do with good results ( hey nobody is perfect so I will learn if somebody has a better method) 1/8 green tungsten, 1/16 rod for small cracks ect.

Ground area with a good , clean carbide mill then clean a couple of time with acetone only, do not use any type of brush or sand paper .\

Hope this helps!

 

John; are you really sure you haven't lost my number??

The contamination you are getting is because the block is NOT hot enough, and you are holding the rod too close. The rod is almost at melt already, and when you try to put it in the puddle, it has already become ashes.
You will also need a helium mix. NO Chemtool or spray of any kind. As said before, use Acetone with a stainless toothbrush, NOT steel. If it doesn't say stainless on the brush, buy ones that do.

 

If you're not frightened off by the price, get a bottle of either medical grade or insturment grade helium. A 275 bottle goes for about 100.00, and it goes pretty fast at 75 CFH. Don't bother trying to use "baloon grade" helium, it isn't pure enough, and will NOT work. DC straight polarity, sharp point on the tungsten, and don't try to overdrive it, just run enough heat to get the job done. No preheat is necessary, but with castings be quick to get in and out. Peen the weld with a small ball pien hammer to stress relieve the weld immediately after welding, to prevent cracking.
If you use 4043 filler rod, you'll get a very pretty weld (once you learn how) thats' very ductile. If you use 5356 rod, you'll get a black deposit around the weld area, but that doesn't affect the weld in any way. Use a stainless steel toothbrush that is dedicated only to aluminum to clean the black deposit before resuming welding. The 5356 is stronger than the 4043, but is less ductile.
This process is terrific, but requires practice to achieve good results.
BTW, if you have the green (pure) tungsten around, make absolutely certain you NEVER try to use it for anything other than AC welding on aluminum. You will pull your hair (assuming you have hair) out in huge clumps trying to figure out why there are bubbles in your welds on steel.
I hope this helps.
Henry

 

This is why I like this site so much!!! I Know that what I did work because I have done it, But NOW I know how the people that REALLY has done it , DO IT. Thanks guys!

 

We use a 4181 rod for welding cast blocks and heads and the 4043 rod on billet heads and forged blocks.
After the initial cleaning we will take a torch to heat the area up a little bit and clean some more. This opens up the pores in the block so we can get the oil and other contaminants out of it.

 

Bob i have not lost your # just do not like to bother you with my small time bullshit,you big hitter guys have a tough time going to the bank all week,and bench race with Englanders who want run in the 5's