[Sirrotica]

Don't even try to work on the manifolds without jacking the engine up on the side you're working on. Take the motor mount bolt off on the side you're working on, and jack that side of the engine up, you'll be able to put the bolt in and have a helluva lot more room to work. It may, or may not, seal the head to the manifold.

These manifolds warp over time so if it's flat it should seal, if not you're probably going to have to remove it and either replace it, or have it surfaced. Be aware that these bolts have to be the correct length, some will bottom out in the holes (end ones) depending upon which ones you're working on. You should also chase the threads in the head with a bottom tap on the end bolt holes, I would chase any threads as rust will get in the backside of the open holes and screw up the threads.

All Pontiacs since 1955 use 3/8 inch coarse thread bolts to hold the manifolds to the head, but length is critical for them to tighten the manifold to the head, instead of bottoming out before they tighten the two parts together. The end bolts intersect into the head bolt holes so if the bottom out on the head bolts they won't seal the end ports. Many hardware stores only stock bolts in 1/2 inch increments, you need ones in 1/4 inch increments.

On the RA manifolds they only used 4 bolts to hold the casting to the head because of the design, they have to be flat to work well though. The bean counters left out bolts too, and the standard logs went to using only 4 bolts, out of six, from the factory.

Of course the steel shim gasket must be in good shape too to seal, they do tend to rust away as they age.