I'm guessing you have some rust wedging going on. The gap between the bolt and manifold has filled with rust over the years ceasing it up. Steel expands 10x when it oxidizes so it develops an incredible amount of compression in a situation like this which causes the parts to bind up. I've inspected bridges fabricated from riveted components where the rust has warped 3/4" thick steel plates up to 2" over a 6" length. It's really amazing. I have pictures at work but just don't have access to them at the moment.nwav8tor wrote:Hey, I am still alive and actually got some work done on the vette! I've been stuck the last few days trying to get the RH exhaust manifold off the block. One of the bolts had a head snap off, but I can't seem to get the manifold to simply slide off the remaining shaft. Been working on it for a couple of days using a propane torch, pry bars and a BFH, but it won't move more than about 1/2 inch CW and CCW around the bolt but then hits bolts for the heads on either end. Even tried to use an extractor, but my cobalt bits keep breaking before I can get a big enough hole started.
I suggest you buy a high quality drill bit and drill out most of the remaining stud. This will relieve the compression and allow you to remove the manifold. I'd stop about a 1/2" from the block so you have something left to "grab" onto with a pair of vice grips once the manifold is removed.
If all else fails drill the stud out completely and either retap the hole or insert a helicoil.