Welding Tips and Tricks

I've got an old Fenton cast aluminum intake manifold for a Chevy 235 Inline 6 that I've had to grind away at to get the headers and intake to fit the head properly. The intake has a water jacket underneath it to help with heating. I was a little worried that my grinding might eat into the jacket, but it seemed good until I started poking at a little discoloration with a probe. Turns out there was some sand inclusion in the casting that opened up a hole in the jacket about 1/8" diameter. I'd like to plug that sucker up, but I don't want to destroy the manifold in the process, so I figured I'd ask for help before I dive in.

I've got a Millier Dynasty 200DX that I've welded aluminum with before with varrying amounts of success. Best thing I did was repair a broken step on a Mack truck. I also welded up a license plate bracket on a hardtail motorcycle that's still holding together after 3,000+ miles, so I think I can pull this repair off.

I know I will probably need to preheat the manifold (I was thinking 200 - 250 degrees), but what the heck should I set my machine to?

I'll be honest, I bought the Dynasty a few years ago and just started using it - I had no idea what it could do until I started poking around on here and actually read the manual (crazy idea, huh?). So I don't know where to set the pulser or anything like that. I don't have any Helium and probably can't get any anytime soon (work is over the top busy).

Thanks for the advice,
Jay

You won't need helium, and you won't need pulse for this repair.

Preheat is a definite. 350-400 is not out of the question. Stick it on your gas grill, and be prepared to weld it there and close the lid so you can let it cool slowly. Welding cast anything is a diferrent animal.

If you have a path through the water jacket to do it, use a short length of copper tubing to reach in and back up the hole (as tightly as possible). It will serve to carry away excess heat and keep the torch from turning your small opening into a coin slot. For cast, I wouldn't use an alloy harder than 4043, and if you have or can get it, 3003 would be the material I'd pick. It doesn't work-harden, quench-harden, or any of the things that might give you trouble on a cast part.

A cast manifold should be at least 1/4", so be prepared to crank the machine up. I'd actually start around 100-120 until I had the hole closed (so you don't melt the edges too far back, even with the copper), then go wide open (max out the 200DX--good machine) to fill. Put the grill on low, and let it sit for a good half-hour, then turn the grill off, cross your fingers, and see what you have when it's cool.

Your mileage may vary....

Good luck,

Steve

Thanks!

Crap I'm nervous about this. It was tough enough to find this manifold in the first place. Oh well, worst case scenario - it cracks and I have to fab up an entirely new one.

+1 for Otto, advice I agree with. I would add one other thought.

Contamination in the weld can be an issue. Especially if you cannot clean the inside. It can bubble up through the weld. Point is the repair, in this case, does not need to be as thick as the parent material.

Good luck.

Hi there,

This sounds like a situation where the Dura Fix Aluminium rods might do the trick. Never used them but I've researched them and they may help.... ....?

Mick