Exhaust plug

I have a strange situation on my recently purchased 74 GTS C&F. On each bank of cylinders, where the manifold is attached to the engine, a "plug" has worked it's way loose and I have lost one. When it fell off, the engine sounded as if the exhaust had been disconnected at one cylinder, like a golf ball in a coffee can. I talked to the previous owner and this had happened to him before on the driver side, rear bank. Although that plug was there this time it was only finger tight and was an obvious replacement from the original. He was not aware over any others working loose, the other was near cylinder 3 i think. I'll include pictures of whats missing along with properly installed units. They are located on an extension from the engine that the manifold attaches to, i think. Any idea where to get replacements? The emission equipment had been removed, don't know if this is part of that? On the removed parts, i did notice a flange that seems to match the diameter of the opening, but am not sure. Any help is appreciated. I'm having trouble downloading/viewing pictures and video on my iMac, will do my best to include some asap. Thanks

 

Thanks Tony,

These are not the tubes that I think you are referring to but are located at the base of where the manifold connects to the engine. Looks like they have an allen or some other type sunken head and screws in flush to the extension that allows manifold to connect to engine. If I could get pics up it would help, I'm still trying. Not a big Apple fan right now.

 

Think I got it!
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I have the original pieces off the injection tubes. I've gone to several places with no luck so far, any idea what the width is? They don't have to be flanged like the original, correct? Thanks

 

One of the plugs I removed was a 3/8 in piece, flanged at each end with a cap on one end to make tightening it down easier. According to the previous owner, that had worked it's way loose a couple of times. I have found copper 3/8 counter sunk plugs at the hardware store, but the thread pattern is not the same as the original injectors but matches the plug i just described. Probably why it keeps coming out. Perfect world, we find the correct size plug and insert. It can be counter sunk or have a head, really doesn't matter as long as it forms a semipermanent seal and doesn't fall out. What have others done in the past? Any suggestions are appreciated?

 

I tried running a search but find it's almost impossible with this new format. I emailed one of the moderators with my frustration. If you have a link, that would be great. Thanks.

 

Great stuff, clearly shows what I need. Where do those plugs come from? Thanks.

 

Oil drain plugs are 14mmx1.5. Bought a couple and will try that for now. Looks like whats needed are the same plugs used next to the spark plugs? Seems like there should be a resource to be able to go to to purchase.