I was there when it happened and I still don’t believe it:



This started out as a leaking rear Y-pipe. I bought a used rear Y-pipe from a local vendor (supposedly from another ’79 model) which ended up being an aftermarket pipe that didn’t fit. So, “while I was at it”, I figured “why not just go with a dual exhaust?” I couldn’t find a muffler shop that would do it locally so I ordered a kit from a reputable dealer that fabricates their own kits. Shouldn’t be much of a problem for a competent shade tree wrencher like myself, I thought.

Last Saturday, I was attaching the first exhaust section to the passenger side exhaust manifold. I was tightening the last stud when I noticed “hey, this thing’s getting’ kinda wobbly…”









Well, I guess all things happen for a reason. It’s better to discover this problem while the car is up on jack stands, as opposed to later on down the road. The only cause I can think of is that maybe the heat riser, which is normally installed between the manifold and exhaust, wasn’t opening fully and the manifold got hot, then cooled again, again and again.

For most of us, we would see this as an opportunity to slap on a pair of headers. However at around $300 for a good pair plus having to cut up the new exhaust to accept a collector and a flange, this is getting beyond my budget. I have $300, I just don’t have $300 in mad (Corvette) money.

Most will just roll their eyes and consider this a trivial setback. If this were an early ‘70s shark, I’d be more dedicated to it but I no longer have the time and money to pour into this hobby. After I get this job done (hopefully, someday) I need to sell this car and move on to a cheaper hobby – maybe handmade toothpicks.

 

You can get shorty style headers that will bolt right in place of the stock manifolds
Should be around $80-$100, check Summit and Jegs.

 

Sorry you had this problem. Looks like it had been cracked for awhile You could probably pick up a used manifold somewhere cheap. Get rid of the heat riser altogether; they cause more problems than the are worth. I love my '79; it has been a lot of labor, but a labor of love.
Bernie

 

Yes but I assume that the shorties won't attach to my existing pipes.

 

Well, the heat riser has been a point of contention. Corvette Central says the passenger side pipe is cut shorter to compensate for the heat riser but I couldn’t get the pipe to align with the cross member when the heat riser was in place, so I removed it, as shown in the photos.

Pretty crude way of getting the car warmed up quicker to reduce emissions. I think it took Detroit a decade or so to learn how to make cars burn clean without using all of these horsepower-robbing band-aid approaches.

 

I've got an exhaust manifold on an old truck that's headed in that direction.

 

Sent you a PM

 

The shorties should bolt in - they have the same 3-bolt flange as the manifold.

 

OK, thanks - I'm just concerned about the flange location being different than the OEM manifolds. Unless they're pretty close, the pipes may not align.

 

They bolt in place with the stock exhaust, your pipes were bent to fit the stock manfolds so they're very close/identical to stock... it should fit perfectly. You may need different bolts but you can get these at HomeDepot....

 

Now you have seen firsthand why airplanes sometimes just drop out of the sky, or a race car will slam into a will for no obvious reason...or worst yet mysteries highway accidents with big rigs...etc.

Metal fatiques and will fail. This is why aircraft parts are tested, inspected, and replaced after a certain cycle period even if the part looks good to the naked eye.

Good think it happened at home on the jackstands. Imagine if that pipe snapped and dropped down at 75 mph!

 

I have shorties in my cobra. You might need a special socket when removing your sparkplugs. If they don’t match correctly, I recommend using a stainless flex adapter tube, worked great for me. Other than that, they’re fine.
As far as your old manifold goes, you must of had some serious spitting or hissing noises, no?

 

Amazingly, no. I’ve had exhaust leaks on other cars and could always hear them. This was a surprise.

 

Maybe I can squirt some of this on there, slap on a hose clamp and call it a day:

 

I think that will work!
Bubba

 

If you replace the exhaust manifold with a new/used one and you're worried about the extra space that's left after you remove the heat riser you can have someone just braze the heat riser butterfly so it stays open, or remove the butterfly from the assembly completely.