Exhaust manifolds

[Happy_dan]

Hi all, a couple of things I am trying to figure out. I have pulled the motor from my 68 C-20 so I can change all the seals and gaskets etc.

I noticed a crack where a stud goes into the drivers side exhaust manifold. My first question is can I get away with the crack (I don't think so and it will break eventually) or do I need to address it? Second question is can I fix it (I don't think you can weld cast) and if not, where can I get one the same as what I have? I really want to keep it stock looking.

Here is the crack:


Second part of the question is about the casting numbers. They are very hard to read. The passenger side is better than the drivers but both are hard. Do we have any experts here that can enhance the pictures to make them easier to read?

I can send high res versions if it helps. I thought if I can read the passenger side, it might help with the drivers side??

This is the drivers side that is cracked:




As always thanks for the help.

I plan on pulling the heads and having the valve seats replaces so I can use modern gas and replace the valve seals too. Looking forward to getting it back together but have to resolve this issue!

[Andy4639]

The junkyard will have them They came on cars also but they don't have the turn in them for the truck. But if you have a yard with some of these trucks you can find them laying around. Some have the AC & alternator mounts on them some don't. I have found them laying in the back of trucks and on the ground where some body took them off and didn't want them.


https://www.facebook.com/marketplace...code=undefined

[cj847]

I bought new manifolds for my truck. I think they were $125 for the pair. Not worth trying to find a used one in my opinion.

[Happy_dan]

Originally Posted by cj847

I bought new manifolds for my truck. I think they were $125 for the pair. Not worth trying to find a used one in my opinion.

I would be happy to buy new ones but need to make sure I get the right ones since I can't read the casting numbers. I need to be able to mount alternator bracket on the end. No AC. Any suggestions in where to look?

[Happy_dan]

Can anyone tell me what the casting numbers should be? I think it would help my search.
I tried media blasting and using a silver sharpie to bring the numbers out better but still can't ready them.

Could it be 3865183??





Here is what the driver side full manifold looks like:

[gmc684x4]

67 72 trucks have two styles of exhaust manifolds

The ones with angled output are 2 wheel drive ones and ones that go straight down are 4 wheel drive units

[Andy4639]

The link in my first post is a set. I posted it for you!
Does your truck have the heads with bolt holes in them if not they are not going to work for you.

[Happy_dan]

My apologies. I missed the link first time. That Facebook post is passenger side. I need drivers side and I need the end to be able to bolt the alternator and bracket to. Not sure what you mean mean by bolt holes in head? The manifold bolts goes through the manifold then into heads

[LockDoc]

Originally Posted by Happy_dan

My apologies. I missed the link first time. That Facebook post is passenger side. I need drivers side and I need the end to be able to bolt the alternator and bracket to. Not sure what you mean mean by bolt holes in head? The manifold bolts goes through the manifold then into heads

I will look in the morning and see what I have. I have a few of them.

LockDoc

[dmjlambert]

The guy who rebuilt my engine found cracks in my original exhaust manifolds. He took them over to a table put on a welding helmet and fixed them. Actually he said he was brazing them, but I don't know the difference between brazing and welding. They turned out good as new.

[Steeveedee]

You can weld cast iron, but for an exhaust manifold it could be more money than buying a new one.

[LockDoc]

Originally Posted by dmjlambert

The guy who rebuilt my engine found cracks in my original exhaust manifolds. He took them over to a table put on a welding helmet and fixed them. Actually he said he was brazing them, but I don't know the difference between brazing and welding. They turned out good as new.

Brazing uses an Acetylene torch and brass rod. You can buy flux coated rod or you can use un-coated rod and heat the end of it and dip it in a can of flux powder. It works very well on cast iron parts if you know what you are doing.

LockDoc

[Andy4639]

Originally Posted by Happy_dan

My apologies. I missed the link first time. That Facebook post is passenger side. I need drivers side and I need the end to be able to bolt the alternator and bracket to. Not sure what you mean mean by bolt holes in head? The manifold bolts goes through the manifold then into heads

Some heads have the bolt holes in the end of the heads to mount the alternator are compressor on them without the exhaust manifold.

[Happy_dan]

Ahhh, I see now Andy. Thank you. I'll have to look.

Still would love to have the original style. Truck is on pretty good shape and mostly original and trying to keep it that way to avoid me suffering project creep and going nuts on the truck! I really just want to drive it!

[MARKDTN]

I would try to save that one. If you have a stick welder you can get a high nickel rod and weld it. Heat it up with a torch before you do. If you ruin it, you were going to replace it anyway but I think it can be saved.

[Grumpy old man]

put a want to buy ad in the classified section and just buy what you need from another member .

[Already Gone]

I picked up these for my truck and I have factory A/C.. If you need more detailed pics let me know.

[Jcfcamaro]

I'd just have it welded. Pretty easy to do.I used hobart nomacast 1/8 rod to weld mine up. You need to clean up the area with a wire well or sand blast it,then grind or cut a small v groove in the crack area. Heat the manifold up in oven or torch then weld it. Any good machine shop should be able to do it pretty cheap. I'd call around and ask and they might want to see it first.

[Happy_dan]

Originally Posted by Jcfcamaro

I'd just have it welded. Pretty easy to do.I used hobart nomacast 1/8 rod to weld mine up. You need to clean up the area with a wire well or sand blast it,then grind or cut a small v groove in the crack area. Heat the manifold up in oven or torch then weld it. Any good machine shop should be able to do it pretty cheap. I'd call around and ask and they might want to see it first.

Thanks, exactly what I was able to do. Found a local guy that can do it for me. I am going to media blast it in my cabinet and clean and prep it all for him and he will repair it.