Stitch repairing cast iron

[727]

I had a set of 915 heads built for my 400 BB about 6 months back. I finally completed my home built test stand on Sunday and my engine was begging me to run. So for my first start of the 400 I fired it up ran the engine up to 2500 rpm' then noticed anti freeze coming out of the exhaust header gasket just fwd of the #8 exhaust port. At first I was hoping it was a head stud or freeze plug leaking. At least I tried to convince myself it was going to be a simple fix. When I removed the header and gasket I pressurized the cooling system with air and found a 1" vehicle crack on the exhaust flange area. I called the(unnamed) machine shop and the machinist said he didn't see any crack when he magnafluxxed the heads.
The machinist says he can pin/stitch this crack and it will never leak again. Has anyone had any luck good or bad with this style repar? I'm not all that afraid of doing this because it's leaking outside the block and not into the crankcase.
As a side note I bought a YJ jeep once with a bad engine and it turned out that someone had installed a stitch across the combustion chamber on the head. That seemed like a bad idea as this area seas a lot of flex.

727

 

[flyingfarley]

I have had two cracks stitched...one in an intake manifold runner, and one in an intake runner in the head...both worked great with no problems.

Mark

 

[khryslerkid]

Any pictures?

Correct me if I'm wrong but heads are cast steel which welds easily compared to cast iron. V notch the crack, pre heat and weld with mild steel. Grind flat to surface and you're good to go.

The only thing that I worry about with cracks is what you don't see internally. Will it leak later inside somewhere in the future? If you know its just a external crack you should be good. If there is any doubts about the area that is cracked, for pease of mind, you could always get another head and have it machined to exchange your valves that you already have.

Good luck...

 

[69Bee]

Any pictures?

Correct me if I'm wrong but heads are cast steel which welds easily compared to cast iron. V notch the crack, pre heat and weld with mild steel. Grind flat to surface and you're good to go.

The only thing that I worry about with cracks is what you don't see internally. Will it leak later inside somewhere in the future? If you know its just a external crack you should be good. If there is any doubts about the area that is cracked, for pease of mind, you could always get another head and have it machined to exchange your valves that you already have.

Good luck...

Heads are cast iron as well. There are people who weld cast iron with different methods, and get varying results. The best way to weld it is TIG or spray metal welding. An oven is a must to properly heat the cast iron, and allow it to slowly cool to prevent cracking of the welded area. Pins or stitching (Lock-N-Stitch) works very well, and has worked for me. The most important thing to remember is no matter which method you use, the ends of the crack need to be drilled to stop it from continuing. Also, each crack should be evaluated individually for the appropriate repair method. Not all crack repairs work well in every situation.

 

[727]

I could take a pic of the area but the crack wouldn't show up. I had to pressurize the cooling system to see where it was leaking. It is very hard to see with the. Naked eye.

 

[747mopar]

I saw a cool idea in a Mopar mag on how to do a home repair on these, they started at one end and drilled and tapped the hole then threaded I believe a cast iron rod into the hole then kept repeating the process overlapping all the plugs. Once it was ground smooth the crack was gone, an idea? Is this what they call stitch repair?

- - - Updated - - -

My dad has had good luck TIG welding cast iron with nickel rod.

 

[Goldwing1800]

I worked at a machine shop for about 20 years-we did the stitch crack repair a ton of times and had very few problems. If your guy has some experience I would not hesitate to do stitch repair. Trying to weld iron heads makes more problems than it fixes most times.