Connecting cast iron to steel for cut-out exhaust?

[Deuce Rails]

I was thinking about getting a pair of the JC Whitney exhaust cut-outs. I like the idea of a dash mounted knob to effectively switch the exhaust from mufflers to straight pipes. Has anyone used 'em before?

They're cast iron, and I was wondering what the best way to connect them to mild steel was. Can you MIG steel to the cast iron? Or, what's the best way to connect these suckers?

Thanks,

Matt

[Rocky]

Once upon a time I split a 235 Chevy exhaust mainfold and cut a slit through the front, top and botttom wall of the manifold to insert an 1/8th inch separator piece. I did it to separate the front 3 cylinders from the rear 3 to get a better sound. I used a common cut-off saw and made a paper template to get the shape just right...transfered the template to metal and welded it to the CLEAN cast iron with my mig welder. I brazed the new cast iron outlet onto the cast manifold and everything was just rosy for about a year. The brass let go one day and I ground everything clean and used nickle rod to re-attach the outlet. The mig welded partition was still ok at that time so I didn't mess with it... as far as I know, the manifold is ok still...

[manyolcars]

When I got the JC Whitney exhaust cutouts, I found that part of the flapper valve is omitted during manufacture. I cut the cutout in half, added the missing parts, welded the cutout back together with my arc welder and stick welded them to my pipes. No probem! been good 10 years now

[38Chevy454]

Officially welding cast iron is very difficult to do without cracking, which occurs along the fusion line of the wled filler and the cast iron. That is why lots of preheat and slow cooling are used. Nickel rod is commonly used as it is relatively ductile to help the cracking problem. A MIG will weld it together, but you may have some cracks. Whether that is a concern or not depends on the load (stresses on the joint) and if the crack actually causes any problem. The best way to join the cast iron cutout to the mild steel exhaust tubing would be to braze it.

One thing that I have heard on those cast iron cutouts is that they leak, even when you have the flapper in position of the cutout closed. I also think you have to run two cables, one for each cutout.

[yorgatron]

yeah,cutouts might leak,but so do my rusted out glasspacks! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Zodoff]

drill a couple of holes in the cut-out,put your mild steel tubing in there and mark of the holes.drill,weld in some nuts,or use some clips.. and use a good amount of gun-gum exhaust pasta,or some other stuff that can take the heat..

Put plenty of oil on the wires.they can be a little hard to pull.

Z

[manyolcars]

[ QUOTE ]
Officially welding cast iron is very difficult to do without cracking, which occurs along the fusion line of the wled filler and the cast iron. That is why lots of preheat and slow cooling are used. Nickel rod is commonly used as it is relatively ductile to help the cracking problem. A MIG will weld it together, but you may have some cracks. Whether that is a concern or not depends on the load (stresses on the joint) and if the crack actually causes any problem. The best way to join the cast iron cutout to the mild steel exhaust tubing would be to braze it.

One thing that I have heard on those cast iron cutouts is that they leak, even when you have the flapper in position of the cutout closed. I also think you have to run two cables, one for each cutout.

[/ QUOTE ]
*******When I got the JC Whitney exhaust cutouts, I found that part of the flapper valve is omitted during manufacture. I cut the cutout into two pieces , added the missing parts, welded the cutout back together with my arc welder and stick welded them to my pipes. No problem! been good 10 years now********
38Chevy454 is talking about a different animal. I am telling you about the JC Whitney exhaust cut outs and what I did and how well it continues to work. I dont think he read the part where I stated that "part of the flapper valve is omitted during manufacture". you will want to cut your cutout open so you can add the missing part to the flapper. Then your ordinary, cracker box stick welder with 6011 rods WILL weld the cutout back together just fine and you CAN weld your exhaust pipes to the cutout. I have done this and it is still in excellent condition 10 years later. and OF COURSE you have to run a cable from the dash to each cutout. DUH!

[Deuce Rails]

Thanks, Manyolcars.

Just out of curiosity, what part of the flapper valve was missing?

I don't have a stick welder. I can I just use regular old copper-coated 0.035 MIG wire with argon? Should I use the same settings I would use with just the steel pipe, or go a little hotter with the cast iron?

Thanks,

Matt

[drgnwgn289]

remember that there is a difference between cast IRON (often called Pig iron) and cast STEEL. It isn't extremely difficult to weld mild steel to either one of them, but it is very hard to weld cast Iron to cast Iron and have a weld with any integrity. It is very possible that thos JC Whitney cut outs are cast Steel and very weldable.

P.S. its also easier to weld to cast iron if the whole part is evenly heated first, and your weld will be stronger if you allow it to cool very slowly (i.e. don't go through it in a bucket of water.

[LIMEY]

Any thoughts on tig welding cast, just done a small amount on a cyl head & it flowed real nice with no filler rod.

[drgnwgn289]

Hmmm, never done it, but if it works it works. One thing though, is that the heat concentration is so high with tig, and usually, when welding cast iron, the best results are achieved with as close to uniform heating as possible...

[Bugman]

I've always gas welded cast iron. If you don't have cast filler rod, mild steel filler works. I recoment the use of flux though. There is a special type for cast, but I don't know what's special about it.

-Bugman Jeff