65 Exhaust manifold crack repair

[Jerry G.]

This restoration is driving me a little nuts. I'm tightening up the nuts holding the exhaust pipes to the exhaust manifold. the torque wrench is set to 25# which should be good for this, I thought. All of a sudden there is a slight pop and the manifold is cracked around the stud. It's a bad crack. Now I have to take this whole thing apart again. AWWW My question is can cracks be repaired, if so how is the best way. And assuming I can muster the strength to put it back together what is a reasonable torque to use to tighten the nuts. I'm getting a LOT of respect for someone who has done a frame off.

[Joe L.]

Re: 65 Exhaust manifold crack repair

Jerry-----

The ear cracked off of the manifold not because of excessive torque but because of uneven tightening of the 3 nuts OR because of improper installation of the exhaust pipe-to-manifold flange and packing assembly.

Usually, I do not recommend the repair of cast iron exhaust manifolds, especially those which have seen long service and the metallurgical changes which repeated severe heating and cooling cycles have caused. Repairs are especially difficult in areas of the manifold requiring structural strength like the flange, which is where your break is.

In any event, if you wish to try a repair, all you have to lose is the cost of having it done. Seek out a welder VERY experienced in cast iron welding and using special high-nickel content welding rod designed for cast iron welding.

[Patrick H.]

Re: 65 Exhaust manifold crack repair

I was lucky enough to have a similar crack corrected this past spring on my 71's exhaust manifold in the same area yours broke. To date it has worked well, is essentially undetectable, and has not re-broken.

As Joe says, find someone who is experienced. I checked with a local engine machine shop to get references.

Patrick