67MustangJDM

Ive got a 1967 200ci six cylinder with a little crack that's a little wider than a hair right below where the carburetor mounts. The crack is no longer than an inch, if that. The question is how can I fill the crack in? Can I weld it or what?

Aussie66Fastback

may be welded but you might need a specialist to do it. i had a hairline crack in one of my heads welded about a year ago. so far so good.

andrewmp6

Cast iron is a real pain in the *** to weld and you could mess it up real easy.I would look for a new manifold.

valley firearms

If you can weld and feel like trying, read this post. If it were a moving part or a part that you depended upon for safety reasons I'd say replace it. But since it's only a manifold, why not. I'm sure if you cleaned it good enough epoxy would work.

http://www.smokstak.com/forum/showthread.php?t=9102

There several different methods you can try. It won't hurt to try.

htwheelz67

buy a new head, I used to hot rod 200-250 sixes even if you repair it it WILL crack again. With cast iron you have to heat it red hot and then weld it.

There is some really trick stuff out there for the 144-250 sixes now, even aluminum cross flow heads that have a bolt on intake. There are cast iron cross flow heads from Austrailia that are far superior than the integral stocker, on the cheap find a good rebuilt 170 head or use a 250 head and mill it to get compression back up.

They even have 4 valve heads (aussies) for those ol sixes and they increased the displacement to 4.0.

my77stang

there is another option. since the crack is where it is you can grind down into the crack a little bit and fill it with J.B. Weld. I know that sounds cheesy, but it will hold up very well and cost you 5 bucks.

92ponyranger

Cut a V shape into the crack, heat it with a torch and then weld it. After welding it, cover it with something to prevent it from cooling too fast and keep the wind off of it.

68 Coupe

I have had really good success on cast iron using the following technique.
Drill a 1/8" to 3/16 hole in either end about 1/4" beyond the crack. This will insure that the crack doesn't spread after you weld it. The best way to do it is to heat the manifold to 500+ deg to see the extent of the crack. Let it cool down after yopu have drilled your holes. Weld it with a nickel/nickle (sp) electrode such as "Econocast" 55 from MG. As long as the electrode designation is ENiFe you should be fine.
The procedure for welding is as follows. Start at one of the holes you drilled and weld about 1/4" and stop. As soon as the weld cools below the cherry red stage, use the pointed end of your chipping hammer and "peen" the weld. what you are trying to do is spread the weld out a very little bit to help compensate for the lack of movement in the cast iron due to shrinkage as it cools. The cast is very hard and brittle, but the nickle is soft which allows it to cool without cracking. Wait until the welded area can be touched with your bare hand before you weld again. When cool, weld another 1/4" or so and repeat the peening process and let it cool again. Between welds, listen for a sound like snapping a piece of plastic in half. No sound = good weld. The peening is critical, but dont pound it into oblivion. You should see 1/16" divets in the surface of your weld if you are doing it correctly. I would use a 3/32" or 1/8" diameter electrode. Cooler is better (ie less amperage will get you farther)
Above all, DON"T pay someone a boatload of money to do this if you have your own SMAW welder at home. It really isn't that hard to do

my77stang

or you could spend 5 bucks and never worry about it again

68 Coupe

My mom washed my mouth out with soap last time I said "JB Weld"
Seriously though, cast is much easier to weld than most people think and I would feel much better having my manifold welded than epoxied.......