I picked up a 94 Z28 engine/trans and noticed both rear-most bolts were not there. I have removed one manifold and it looks as if it was sheared off. Is this the way these manifolds bolt up or by chance, have both rear bolts been broken off at some time?

 

Stock manifolds? I know when putting my LTs in, the rear most bolt was so rusted it broke when I went to remove the stock manifolds. My pacesetter LTs didn't need that whole and there is one a little closer to the front of the car that it used, dodged a bullet in not having to remove the head to get it out, no chance to get a tap or easy out in back there lol


Sounds like it was modded with LTs and then they un-modded and sold it, Id bet they have been broken off, if you can get a picture of it that would tell for sure. I know thats how mine would have been if I had put the stock manifolds back on.

 

The rear exhaust manifold bolts suffer alot of heat cycling stress and they break on their own. If you search the various forums you'll see alot of threads about these bolts missing. I've read GM even came out with a improved set of bolts you could buy over the counter for a fix but they sometime break also. My rear one on the pass side is broke off flush with the head and nobody had ever put a wrench on it. Luckily headers don't use these particular bolt holes so it's a non-issue with headers.

 

I may have figured it out. I just positioned one header up to the cylinder head and what I thought was going to be used as a bolt location won't be.

 

If your putting on after market headers they should use the inner most one. the stockers use the outermost set which is the hole that has the broken bolt in it....