Anybody know if you can weld cast iron?

[reddy351]

Well, I was out in the garage last night, getting ready to put the finishing touches on my GT40 head porting job. I got all of the bowls shaped, ports gasket matched and so on. (Took out a lot of metal.) I was doing some final shaping and then some polishing when I did this...

Here's a little closer...

I'm a little ticked because I have A LOT of time getting to this point. It's just the one exhaust port but they are all shaped EXACTLY the same. I'm worried that the metal on all of them is too thin. Any opinions? I could just buy a single head and port it to match the one without the hole.

I'm pretty sure that cast iron can't be welded, but I'm not positive. Anybody know of a good solution? Otherwise, it looks like I have some additions to the scrap metal pile.

 

[RFMustangGT]

if not weld, what about that epoxy stuff some people use for extreme porting jobs? might be able to dab some of that in that hole and polish it down some.

 

[StinkinLincoln]

yes cast can be welded, it depends on the mix of sand in it, too much and it wont hold. ill ask my dad tomorrow since he owns a welding business. he welded something the other day that was cast. got to use the old stick rods on it. ill show he the pics and see what he says.

 

[bill302]

looks like you cut into the water jacket so i would not think an epoxy would work. take them to the machine shop they can tell you something...i have never seen anyone completely grind out all of the valve guide boss, i think thats another problem below is a pic. of the port job i done on mine....

 

[reddy351]

i have never seen anyone completely grind out all of the valve guide boss, i think thats another problem below is a pic. of the port job i done on mine....

Actually, I patterned mine after Thumpers. (He gave quite a bit of wisdom, in that regard.) He takes the guide down just like that, just not as far, evidently. I have pics of his work, that he sent me. They are very similar. (Except for the hole. )

I do agree with the epoxy not working. It's an exhaust port. It sees some pretty hot fumes and a lot of pressure. Prolly would melt anything but a top notch weld.

 

[Dino Dino Bambino]

Cast iron CAN be welded but I fear that you've already left the port walls very thin. Even if you do have the hole welded shut, it's only a matter of time before the high temps. in the exhaust port take their toll and crack the port wall again. You've also ground too much away from the valve guide bosses.
I may be wrong but I think you'd better start looking for replacement heads. I'd be leary about reusing that head if I was in your shoes.
I only just ported my own heads earlier this week and they look similar to Bill's.

 

[HISSIN50]

Did you already send pics to Mike and ask for his thoughts?

 

[WhiteCobra95]

Welding cast iron is do-able but it's very tricky. Usually you have to pre-heat the item to 400 degrees F, weld it up with a special rod, and then slowly cool it down. I've done this a lot with turbos. (It's easier to weld the turbo housing to the exhaust manifold than replace the gasket every couple hours.) This also requires a very experienced welder! The bad part with your heads is the location. It's going to be hard to get a torch in there. I would also be concerned how thin the remaining walls are. If you do go ahead and have it welded up, I strongly suggest checking your oil regularly to look for coolant. Good luck man!

 

[Dino Dino Bambino]

Even if the heads were reuseable (and I don't think they are), there's so much rust on them that the valve seats would need to be reground and the head surface decked. IMO, I think it's better to look for replacement heads.

 

[reddy351]

Even if the heads were reuseable (and I don't think they are), there's so much rust on them that the valve seats would need to be reground and the head surface decked. IMO, I think it's better to look for replacement heads.

I had planned to send them to the machine shop first. For a valve job and milling. You never have the machine work done first, as a single nick to a valve seat with a carbide burr can cause you to send them back to have it done again.

This ain't my first time at the rodeo. I've ported quite a few sets of of heads. I've just never gone far enough to find water.

 

[pwcracer]

hey reddy, I have a set of gt40's that I am no longer going to use.. i will sell them to you fairly cheap. one is perfect, the other has a small bit of damage when my lower half broke and the piston bumped the chamber. It is still fixable, and I have pics on here somewhere.. i was thinking maybe $200 for the set? I just had all the guides and seats redone at the machine shop about 500 miles ago..


When i was home porting the stock lower intake, I broke through the metal just like you did. It was alum of course, and I had it welded..The welder said it was a pita to weld however...